[Pg 527]

University of Kansas Publications

Museum of Natural History

Volume 11, No. 10, pp. 527-669, 16 pls., 29 figs.

  March 7, 1960  

Natural History of the Ornate Box Turtle,
Terrapene ornata ornata Agassiz

BY




JOHN M. LEGLER

University of Kansas

Lawrence

1960

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PRINTED IN

THE STATE PRINTING PLANT

TOPEKA, KANSAS

1960

28-773

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The ornate box turtle, Terrapene o. ornata Agassiz, was studied
more or less continuously from September, 1953, until July, 1957.
Intensive field studies were made of free-living, marked populations
in two small areas of Douglas County, Kansas, in the period 1954 to
1956. Laboratory studies were made, whenever possible, of phenomena
difficult to observe in the field, or to clarify or substantiate
field observations. Certain phases of the work (for example, studies
of populations and movements) were based almost entirely on field
observation whereas other phases (for example, growth and gametogenic
cycles) were carried out almost entirely within the laboratory
on specimens obtained from eastern Kansas and other localities.

A taxonomic revision of the genus Terrapene was begun in 1956
as an outgrowth of the present study. The systematic status of
T. ornata and other species is here discussed only briefly.

Objectives of the study here reported on were: 1) to learn as
much as possible concerning the habits, adaptations, and life history
of T. o. ornata; 2) to compare the information thus acquired with
corresponding information on other emyid and testudinid chelonians,
and especially with that on other species and subspecies of
Terrapene; 3) to determine what factors limit the geographic
distribution of ornate box turtles; and, 4) to determine the role of
ornate box turtles in an ecological community.

The aid given by a number of persons has contributed substantially to the
present study. I am grateful to my wife, Avis J. Legler, who, more than any
single person, has unselfishly contributed her time to this project; in addition to
making all the histological preparations and typing the entire manuscript, she
has assisted and encouraged me in every phase of the study. Dr. Henry S.
Fitch has been most helpful in offering counsel and encouragement. Thanks
are due Professor E. Raymond Hall for critically reading the manuscript.

Special thanks are due also to the following persons: Professor A. B. Leonard
for helpful suggestions dealing with photography and for advice on several
parts of the manuscript; Professor William C. Young for the use of facilities
at the Endocrine Laboratory, University of Kansas; Professor Edward H. Taylor
for permission to study specimens in his care; Dr. Richard B. Loomis for
identifying chigger mites and offering helpful suggestions on the discussion of
ectoparasites; Mr. Irwin Ungar for identification of plants; and, Mr. William
R. Brecheisen for allowing me to examine his field notes and for assistance with
field work. Identifications of animal remains in stomachs were made by Professor
A. B. Leonard (mollusks, crustaceans), Dr. George W. Byers (arthropods),
and Dr. Sydney Anderson (mammals).

Miss Sophia Damm generously permitted the use of her property as a study
area and Mr. Walter W. Wulfkuhle made available two saddle horses that
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greatly facilitated field work. The drawings (with the exception of Fig. 21)
are by Miss Lucy Jean Remple. All photographs are by the author.

I am grateful also to the Kansas Academy of Science for three research
grants (totaling $175.00) that supported part of the work. The brief discussion
of taxonomic relationships and distribution results partly from studies
made by means of two research grants (totaling $150.00), from the Graduate
School, University of Kansas, for which I thank Dean John H. Nelson.

Turtles of the genus Terrapene belong to the Emyidae, a family comprising
chiefly aquatic and semiaquatic species. Terrapene, nevertheless, is
adapted for terrestrial existence and differs from all other North American
emyids in having a hinged and movable plastron and a down-turned (although
often notched) maxillary beak. Emydoidea blandingi, the only other North
American emyid with a hinged plastron, lacks a down-turned beak. The
adaptations of box turtles to terrestrial existence (reduction of webbing between
toes, reduction in number of phalanges, reduction of zygomatic arch,
and heightening of shell) occur in far greater degree in true land tortoises
of the family Testudinidae. Four genera of emyid turtles in the eastern
hemisphere (Cuora, Cyclemys, Emys, and Notochelys) possess terrestrial adaptations
paralleling those of Terrapene but (with the possible exception of
Cuora) the adaptations are less pronounced than in Terrapene. A movable
plastron has occurred independently in two groups of emyids in the New
World and in at least three groups in the Old World.

The genus Terrapene, in my view, contains seven species, comprising 11
named kinds. Of these species, five are poorly known and occur only in
Mexico. Terrapene mexicana (northeastern Mexico) and T. yucatana (Yucatan
peninsula) although closely related, differ from each other in a number
of characters. Similarly, Terrapene klauberi (southern Sonora) and T. nelsoni
(Tepic, Nayarit—known from a single adult male) are closely related but are
considered distinct because of their morphological differences and widely
separated known ranges. Terrapene coahuila, so far found only in the basin of
Cuatro Ciénegas in central Coahuila, is the most primitive Terrapene known;
it differs from other box turtles in a number of morphological characters and
is the only member of the genus that is chiefly aquatic.

Two species of Terrapene occur in the United States. Terrapene carolina,
having four recognized subspecies, has a nearly continuous distribution from
southern Maine, southern Michigan, and southern Wisconsin, southward to
Florida and the Gulf coast and westward to southeastern Kansas, eastern
Oklahoma and eastern Texas, and characteristically inhabits wooded areas.

Terrapene ornata is a characteristic inhabitant of the western prairies of
the United States, and ranges from western and southern Illinois, Missouri,
Oklahoma, and all but the extreme eastern part of Texas, westward to southeastern
Wyoming, eastern Colorado, eastern and southern New Mexico, and
southern Arizona, and, from southern South Dakota and southern Wisconsin,
southward to northern Mexico (Fig. 1). It is the only species of the genus
that occurs in both Mexico and the United States. The northeasternmost
populations of T. ornata, occurring in small areas of prairie in Indiana and
Illinois, seem to be isolated from the main range of the species. The ranges
of T. ornata and T. carolina overlap in the broad belt of prairie-forest ecotone
in the central United States. Interspecific matings under laboratory conditions
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are not uncommon and several verbal reports of such matings under natural
conditions have reached me. Nevertheless, after examining many specimens
of both species and all alleged "hybrids" recorded in the literature, I find no
convincing evidence that hybridization occurs under natural conditions.

Terrapene ornata differs from T. carolina in having a low, flattened carapace
lacking a middorsal keel (carapace highly arched and distinctly keeled in
carolina), and in having four claws on the hind foot (three or four in carolina),
the claw of the first toe of males being widened, thickened, and turned in
(first toe not thus modified in carolina). Terrapene ornata is here considered
to be the most specialized member of the genus by virtue of its reduced phalangeal
formula, lightened, relatively loosely articulated shell, reduced plastron,
and lightly built skull, which completely lacks quadratojugal bones (Fig. 2);
most of these specializations seem to be associated with adaptation for terrestrial
existence in open habitats.

Fig. 1. Geographic distribution of
Terrapene ornata. Solid symbols indicate the known range of
T. o. ornata and hollow symbols the known range of
T. o. luteola. Half-circles show the approximate range of
intergradation between the two subspecies. Triangles indicate
localities recorded in literature; specimens were examined from all
other localities shown. Only peripheral localities are shown on the map.

Two subspecies of T. ornata an recognized. Terrapene o. luteola, Smith
and Ramsey (1952), ranges from northern Sonora (Guaymas) and southern
Arizona (southern Pima County) eastward to southeastern New Mexico and
Trans-Pecos, Texas, where it intergrades with T. o. ornata; the latter subspecies
is not yet known from Mexico but almost surely occurs in the northeastern part
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of that country. The subspecies luteola differs from ornata in being slightly
larger and in having more pale radiations on the shell (11 to 14 radiations on
the second lateral lamina in luteola, five to eight in ornata). In individuals of
luteola the markings of the shell become less distinct with advancing age and
eventually are lost; shells of most old individuals are uniform straw color or
pale greenish-brown; this change in coloration does not occur in T. o. ornata.

Fig. 2. Dorsal and lateral views of skull of
T. o. ornata (a and b) (KU 1172, male, from 6 ml.
S. Garnett, Anderson Co., Kansas) and of T. carolina
(c and d) (KU 39742, from northern Florida). Note the
relatively higher brain-case and the incomplete zygomatic arch in
T. o. ornata. All figures natural size.

Of the several species of fossil Terrapene described (Hay, 1908b:359-367,
Auffenberg, 1958), most are clearly allied to Recent T. carolina. One species,
Terrapene longinsulae Hay, (1908a:166-168, Pl. 26) from "… the Upper
Miocene or Lower Pliocene…." of Phillips County, Kansas, however, is
closely related to T. ornata (if not identical). I have examined the type specimen
of T. longinsulae. Stock and Bode (1936:234, Pl. 8) reported T. ornata
from sub-Recent deposits near Clovis, Curry County, New Mexico.

Ornate box turtles, referred to as "land terrapins" or "land tortoises" over
most of the range of the species, are regarded by most persons whom I have
queried as innocuous. These turtles occasionally damage garden crops and
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have been known to eat the eggs of upland game birds. Terrapene ornata is
seldom used for food. A. B. Leonard told me the species was eaten occasionally
by Arapaho Indians in Dewey County, Oklahoma. Several specimens in the
University of Kansas Archeological Collections were found in Indian middens
in Rice County, Kansas, from a culture dated approximately 1500 to 1600 A. D.
The flesh of T. ornata occasionally may be toxic if the turtle has eaten toxic
fungi as has been recorded for T. carolina (Carr, 1952:147).

Preliminary studies and collections of specimens were made at a number of
localities in northeastern Kansas in 1953 and 1954. Two small areas were
finally selected for more intensive study. One of these areas, the University
of Kansas Natural History Reservation, five and one-half miles north-northeast
of Lawrence in the northeasternmost section of Douglas County, Kansas, is
a tract of 590 acres maintained as a natural area for biological investigations.
Slightly less than two thirds (338 acres) of the Reservation is wooded; the
remainder consists of open areas having vegetation ranging from undisturbed
prairie grassland to weedy, partly brushy fields (Fitch, 1952). Although
ornate box turtles were not numerous at the Reservation, the area was selected
for study because: 1) there was a minimum of interference there from man
and none from domestic animals; 2) the vegetation of the Reservation is
typical of areas where T. ornata and T. carolina occur sympatrically (actually
only one specimen of T. carolina has been seen at the Reservation); and, 3)
availability of biological and climatological data there greatly facilitated the
present study. Actual field work at the Reservation consisted of studies of
hibernation and long-term observations on movements of a few box turtles.

A much larger number of individuals was intensively studied on a tract of
land, owned by Sophia Damm, situated 12 miles west and one and one-half
miles north of Lawrence in the northwestern quarter of Douglas County,
Kansas. The Damm Farm lies on the southern slope of a prominence—extending
northwestward from Lawrence to Topeka—that separates the Kansas
River Valley from the watershed of the Wakarusa River to the south. The
prominence has an elevation of approximately 1100 feet and is dissected on
both sides by small valleys draining into the two larger river valleys.

The Damm Farm (see Pl. 15) has a total area of approximately 220 acres.
The crest of a hill extends diagonally from the middle of the northern edge
approximately two thirds of the distance to the southwestern corner. Another
hill is in the extreme northwestern corner of the study area.

The northeastern 22 acres were wooded and had small patches of overgrazed
pasture. Trees in the wooded area were Black Walnut (Juglans
nigra), Elms (Ulmus americana, U. rubra), Cottonwood (Populus deltoides),
and Northern Prickly Ash (Xanthoxylum americanum). The areas used as
pasture had thick growths of Buckbush (Symphoricarpos orbiculatus) mixed
with short grasses (Bromus japonicus, Muhlenbergia Schreberi, and Poa
pratensis). Farm buildings were situated in the wooded area at the end of
an entry road. The southeastern 74 acres were cultivated; corn, wheat, and
milo were grown here and fallow fields had a sparse growth of weeds.

Most of the western two thirds of the study area, comprising 124 acres,
was open rolling prairie (hereafter referred to as "pasture") upon which beef-cattle
were grazed (Pl. 16, Fig. 1; Pl. 17, Fig. 1; Pl. 18, Fig. 2). Rock
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fences (Pl. 17, Fig. 2) two to four feet high bordered the northern edge,
southern edge, and one half of western edge of the pasture. A wagon track
lead from a gate on the entry road, along the crest of the hill, to a gate in the
southern fence. Except for the latter gate and for ocassional under-cut places
in low areas, there were no openings in the rock fences through which box
turtles could pass. A few trees—American Elm, Hackberry (Celtis occidentalis),
Red Mulberry (Morus rubra), Osage Orange (Maclura pomifera), Black
Cherry (Prunus serotina), Box-Elder (Acer Negundo), and Dogwood (Cornus
Drummondi)—were scattered along fences at the borders of the pasture and
in ravines. Larger trees in a small wooded creek-bed at the southwestern
edge of the pasture were chiefly Cottonwood, American Elm, Red Mulberry,
and Black Willow (Salix nigra). The only trees growing on the pasture itself
were a few small Osage Orange, none of which bore fruit.

Paths were worn along fences by cattle and in several places near the
fence, usually beneath shade trees, there were large bare places where cattle
congregated. Vegetation near paths and bare places was weedy and in some
places there were tall stands of Smooth Sumac (Rhus glabra).

Rich stands of prairie grasses occurred along the top of the hill in the
pasture; bluestems (Andropogon gerardi, A. scoparius) were the dominant
species and Switchgrass (Panicum virgatum) and Indian grass (Sorghastrum
nutans) were scattered throughout. A number of small areas on top of the
hill were moderately overgrazed, as indicated by mixture of native grasses
with an association of shorter plants consisting chiefly of Ragweed (Ambrosia
artemisiifolia var. elatior), Mugwort (Artemisia ludoviciana), Japanese Chess
(Bromus japonicus), and Asters (Aster sp.).

The upper parts of the hillsides were overgrazed moderately to heavily.
Limestone rocks of various sizes were partly embedded in soil or lay loose
at the surface. Depressions beneath rocks provided shelter for box turtles
as well as for other small vertebrates. Native grasses were sparse in this
area and gave way to Sideoats Grama (Bouteloua curtipendula), extensive
patches of Smooth Sumac, and scattered colonies of Buckbrush.

Tall grasses were dominant on the lower hillsides and small patches of
Slough grass (Spartina pectinata) grew in moist areas. Ravines originated
at small intermittent springs on the sides of the hill. The banks of ravines
were high and steep and more or less bare of vegetation. High, dense stands
of Slough grass grew at intermittent springs and along the courses of ravines;
sedges (Carex, sp.) grew where small pools of water formed and created
marshy conditions. Prairie grasses along the tops of ravine embankments
formed a narrow overhanging canopy of vegetation that was accentuated
in many places where the sod was under-cut by erosion or by the activities
of burrowing animals (Pl. 18, Fig. 1). Box turtles frequently sought shelter
beneath this vegetational canopy or burrowed beneath the sod.

On the highest part of the pasture near the entry road several small areas
were nearly bare, presumably because of heavy overgrazing; grasses (except
for scattered clumps of Bouteloua curtipendula and Setaria lutescens) were
absent and dominant vegetation consisted of Buffalo-bur (Solanum rostratum),
Blue Vervain (Verbena hastata), Mullein (Verbascum Thapsus), Ragweed,
Asters, and a few Prickly Pear (Opuntia humifusa). Two small areas on the
pasture completely lacked vegetation; these may have been wallows or the
sites of old salt-licks.

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Three shallow stock ponds, behind earthen dikes in ravines, were present
on the pasture. The pond near the farm buildings ("House Pond") and
that in the southwestern part of the pasture ("Far Pond") were present when
studies of box turtles were begun. The largest pond, in a deep ravine in
the northern part of the pasture, was constructed in June, 1956, and became
filled in approximately one month (Pls. 16 and 18). Pond embankments
were chiefly bare of vegetation because of trampling by cattle; in a few places
at the edge of the water, or in places too steep for cattle to walk, there were
small patches of weeds, sedges, and Slough Grass. The ponds contained some
water at all times of the year. The only vertebrates permanently inhabiting
the ponds in the course of my studies were Bullfrogs (Rana catesbeiana) and
Leopard frogs (Rana pipiens).

The three parts of the pasture in which studies were concentrated were
designated as separate subdivisions. The northwest corner area (28 acres)
was triangular and bounded on two sides by rock fences and on its third side
by a deep ravine. The southern ravine area (17 acres) constituted the part of
the lower southern hillside drained by a series of ravines. The house pond
area (seven acres) surrounded "House Pond." Habitat in these three subdivisions
of the pasture was especially favorable for box turtles.

Observations were made at the Damm Farm on 102 days in the two-year
period beginning in Autumn, 1954; observations were concentrated in the
period from May to October although some observations were made in every
month, January and February excepted. Field work was done chiefly in daylight
hours but a few trips were made to the study area at night.

Routine handling of each turtle captured at the Damm Farm consisted of:
marking, weighing and measuring turtle; recording the exact place of capture,
body temperature and environmental temperature; and, recording miscellaneous
items such as the presence of ectoparasites, injuries, distinctive markings, and
in some instances, the approximate age of the turtle.

Excursions on the Damm Farm were made on foot in 1954 and 1955, and,
in 1956, on horseback. By using a horse, more ground could be covered per
unit of time, a better view could be obtained of immediate surroundings, and,
cattle on the area, being accustomed to horses, did not become agitated as
they would when unmounted persons were nearby.

The entire study area could not be inspected thoroughly in a single day.
It was usually more profitable to find and mark turtles along fences, in ravines,
or in other open areas, and subsequently to follow their movements away from
these areas by means of trailing threads. Turtles could be observed from a
distance through binoculars. Cultivated areas were regularly scanned with
binoculars but turtles were seldom seen there. Behavior was observed by
sitting motionless on rock fences or in a blind on top of a stepladder.

No box turtles were removed from the study area. Specimens obtained in
other areas were used for studies of growth, reproduction, and food habits.
Measurements, weights, and data concerning temperature and ectoparasites
were obtained from specimens collected elsewhere as well as from individuals
on study areas.

Turtles were obtained by hand-collecting and in unbaited traps; the number
captured in a single day ranged from 12 to none. Traps, like those used by
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Packard (1956:9) for tree squirrels, were set in the mouths of burrows and
dens, or—with leads to channel animals into the trap—along ravines and rock
fences. Traps set in the open were covered to prevent death of turtles from
overheating in direct sunlight. Live-trapping provided much valuable data,
although quail, rabbits, opossums, and box turtles were caught with about
equal frequency in the traps.

Turtles were marked by notching the marginal scutes of the carapace by
means of a hacksaw blade, following the code system described by Cagle
(1939). Notches, one eighth to one quarter of an inch deep and wide could
be cut more quickly than filed and were more evident than drilled holes which
often became plugged with soil and obscured. Hatchlings and juveniles were
notched with a sharp knife.

Movements of individual turtles were studied by means of a turtle-trailing
device—similar to the kind first described by Breder (1927) and later modified
by Stickel (1950:355-356)—a tin can, cut to fit the shell of a turtle, with an
axle that bore a spool of thread (Pl. 27, Fig. 1). The device was taped to the
turtle; the free end of the thread was tied to a stationary object. Thread payed
out from the spool through a guide-loop and marked the course of the turtle as
it moved away from the starting point. Because of its great strength and
elasticity (as compared to cotton), nylon sewing thread was used in trailers.
Ordinarily, turtles were unable to break the thread if it became snarled or was
expended. Cattle frequently tangled the thread and displaced it but did not
often break it. Ordinary spools were cut down on a lathe so they would hold
600 to 800 yards of thread. Turtle-trailing provided an accurate record of
where and how far a turtle had traveled, and to a lesser extent, the sort of
activity in which the turtle had been engaged (evidence of feeding, forms, or
trial nest holes). Trailers seemed not to alter the normal activity of turtles.

Prominent landmarks were rare or wanting in most places on the pasture.
Locations of captures (or reference points in the movements of trailer-turtles)
were determined by triangulation with a Brunton compass, using trees along
fences as known points of reference. Rough maps were made in the field and
used later, along with compass readings and measurements, to make a more
precise record of movements and captures on a large map (scale, 100 feet to
one inch) of the study area. Mapped points of capture in grassy areas were
accurate within ten to twenty feet; points of capture in areas where landmarks
were nearby were nearly exact. Areas were measured with a planimeter;
distances traveled by individuals were measured with a cartometer.

Turtles were measured in the field to the nearest millimeter with large
wooden calipers (of the type used by shoe salesmen) and a clear plastic ruler.
Measurements in the laboratory, especially in studies of growth, were made,
to the nearest tenth of a millimeter with dial calipers. Measurements made
on each specimen examined in the field were: length of carapace, width of
carapace, length of plastron (sum of lengths of forelobe and hind lobe), width
of plastron (at hinge), and height. All measurements were made in a straight
line. A spring scale of 500 gram capacity, used in the field, gave weights
accurately within three grams. A triple-beam balance was used in the laboratory.
Unless otherwise noted, measurements are expressed in millimeters
and weights are expressed in grams.

Body temperatures were taken by means of a quick-reading Schultheis
thermometer inserted into the distal portion of the large intestine with the
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bulb directed ventrally to avoid puncturing the bladder. Body temperature of
turtles were altered little or not at all in the few seconds the turtles were held
and no attempt was made (except for small juveniles) to insulate them from
the warmth of my hands. Data recorded with body temperature were: air
temperature (in shade, approximately one inch from turtle); ground temperature
(or water temperature); behavior of turtle; weather conditions; nature of
vegetation or other cover; and, time of day. Unless otherwise noted, temperatures
are expressed in degrees Centigrade.

A maximum-minimum thermometer was installed near the buildings at the
Damm Farm. Notes on general weather conditions were made on each visit
to the study area. Additional climatological data were obtained from the
U. S. Weather Stations in Topeka and Lawrence, from records at the Reservation,
and from official bulletins of the U. S. Weather Bureau.

Stomachs and gonads were removed and preserved by standard techniques
soon after specimens were killed. The dates given to gonads were, in all instances,
the dates when the specimens were killed. Eggs were prepared for
incubation in the manner described by Legler (1956). Females laying or containing
eggs used in studies of incubation were preserved for further studies
and comparison with young hatched from the eggs. Histological preparations
were fixed in ten per cent formalin or Bouin's fluid, embedded in paraffin, and
stained with hematoxalin and eosin.

Names used for the epidermal and bony parts of the shell follow the classification
proposed by Carr (1952:35-39). The terms "scute," "lamina," and
"scale" are used here more or less interchangeably for the epidermal parts as are
the terms "plate," "bone," and "element" for the bony parts of the shell.

The term "form" is used here in the same sense that Stickel (1950:358)
used it in her study of T. carolina—to indicate a depression or cavity made by
a turtle in vegetation or soil. Forms correspond closely in shape and size to
shape and size of the turtle. Forms of T. ornata differ from those of T. carolina
chiefly in being made most often in soil, over which there is a minimum of
vegetational cover. The term "den" refers to natural cavities (or cavities of
unknown origin) beneath rocks, in rock fences, or in cut banks. The term
"burrow," unless otherwise noted, refers to burrows made by animals other
than box turtles.

The known range of T. ornata includes the southern half of the
Grassland Biome, part of the Desert Biome, and that part of the
Temperate Deciduous Forest Biome known as the Prairie-Forest
Ecotone. The species is found in microhabitats that differ widely in
food supply, temperature, moisture, and kind of soil. In spite of its
relatively high degree of morphological specialization, T. ornata is
remarkably versatile in regard to habitat requirements.

Ornate box turtles are relatively inconspicuous in natural surroundings
and collectors seldom seek out and obtain specimens
under completely natural conditions as may be done with certain
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other reptiles and amphibians by turning rocks, tearing apart logs,
or setting traps. Most series of specimens are obtained by hunting
after rains on roads or other natural breaks in vegetational cover.
Detailed information on habitat preferences is lacking.

Low temperature seems to be an important factor limiting the distribution
of T. ornata in the northern part of its range. Box turtles,
like nearly all other reptiles occurring at these latitudes, spend the
winter in underground hibernacula. The depth to which the ground
freezes in the coldest part of the winter is therefore a critical factor.
The ground freezes to an average depth of 30 inches or less over
most of the range of the species; only in the extreme northern part
of the range (southern South Dakota, southeastern Wyoming) does
the ground freeze to an average depth of as much as 35 inches.
Average depth of freezing is, in fact, less than 15 inches over more
than one half the range of the species. The average number of
frost-free days per year ranges from 130 to 140 days in the northern
part of the range to more than 250 days in the southwestern part of
the range.

Terrapene ornata occurs from near sea level to elevations of more
than 5000 feet. Both subspecies are found at both high and low
elevations but luteola is more consistently taken at high elevations
than ornata. The latter subspecies commonly occurs at elevations
above 4000 feet on the high plains in extreme western Kansas and
eastern Colorado; the highest elevation from which I have examined
specimens of T. o. ornata is between 4600 and 4700 feet near Akron,
Washington County, Colorado. The greater part of the known
range of T. o. luteola lies above 3000 feet.

Norris and Zweifel (1950:1) observed T. o. luteola on the Jornada
del Muerto, an elongate plain approximately 4500 feet high,
in southeastern Socorro County, New Mexico; box turtles were
abundant on the level part of the plain and on the bordering foothills
but not at higher elevations where the substratum was rocky.
The authors otherwise noted no preference for any kind of soil.
The principal elements of the plant associations in which the turtles
were found were creosote bush, yucca, mesquite, juniper, tarbush,
and grasses. Lewis (1950:3) reported that T. ornata luteola inhabited
the yucca-grassland zone in Dona Ana County, New Mexico;
he stated (op. cit.: 10) that individuals were commonly found
on roads after rains and in cloudy weather. No specimens were
taken at altitudes higher than 4300 feet.

I have examined specimens of luteola from elevations of approximately
5500 feet in Cochise County, Arizona, and Lincoln County,
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New Mexico. These localities are probably at or near the maximum
elevation at which the species occurs. The texture of the substrate
is the most important factor limiting vertical distribution. Ornate
box turtles, like nearly all other turtles, excavate nests; T. ornata is
a burrower, at least for purposes of hibernation. Populations of the
species, therefore, could not survive in areas of hard unyielding
substrata. Such substrata seem to be the most important factor
limiting altitudinal distribution.

Most of the area in which T. ornata occurs is semiarid or arid.
Average precipitation in the warm season (April through September)
varies from approximately 25 inches in the northeast to less
than ten inches in the southwest. In drier parts of the range,
precipitation is unevenly distributed over the warm season. Long,
hot, dry periods are unfavorable for reptilian activity. T. ornata,
like many other reptiles inhabiting dry regions, survives long periods
without water by seeking shelter (usually underground) and
remaining quiescent. Populations of the subspecies luteola live
under far more rigorous conditions in this respect than do the
more northern populations. Specimens of luteola from Arizona
that were kept for several years in the laboratory under dry conditions
and fed adequately, but at infrequent intervals, were able
to remain healthy and even to grow whereas examples of ornata
kept under the same conditions soon languished and died; luteola
seems to be physiologically adapted for existence under arid conditions,
where normal activity is sometimes possible for only a
few weeks in the year.

The prairies of Nebraska, Kansas, Oklahoma, and northern Texas
seem to provide the most nearly optimum habitat for the species;
in these regions box turtles are active on a large majority of the
days from April to October in years having average or better than
average precipitation and population density seems to be greater
than in the more arid parts of the range.

Activities of man have probably affected the density of populations
of the ornate box turtle in many parts of its range but appear
not to have acted as limiting factors except in certain areas along
the northern edge of the range (Blanchard, 1923:19-20, 24) where
disruption of grassland through intensive cultivation probably has
excluded the species. Unlike certain other reptiles of the Great
Plains (Fitch, 1955:64), T. ornata seems not to have been affected—either
by direct decimation of populations or by disruption of
habitat—by intensive zoological collecting in restricted areas. Environmental
changes such as those resulting from overgrazing and
[Pg 542]
erosion, or from protection of the habitat from grazing could be
expected to cause long-term changes in populations of ornate box
turtles.

Terrapene o. ornata is an omnivorous, opportunistic feeder, primarily
insectivorous but able to subsist on nearly any sort of animal
or vegetable food. The general food habits of luteola are
poorly known but probably resemble those of ornata. Although
kind of food available probably does not limit the distribution of
T. ornata there are indications that it influences population density.
In Kansas, for example, dung insects are an important staple in the
diet and box turtles were found always to be more numerous in
areas where domestic cattle provided an abundant supply of dung
than elsewhere. A similar relationship probably existed in former
times between box turtles and native ungulates. Near extinction
of buffalo in the Great Plains possibly caused a decrease in populations
of box turtles. Henry S. Fitch told me that the number of
T. ornata at the Reservation gradually declined after cattle were
removed from the area in 1948.

In summary, the distribution of T. ornata seems to be limited
by: 1) Presence of a substrate too hard to permit digging of nests
and forms (southwestern and western edges of range); 2) temperatures
causing the ground to freeze deep enough (approximately
30 inches) to kill turtles in hibernacula (northern edge of
range); and, 3) the lack of one or more relatively wet periods in
the course of the warm season, preventing at least temporary emergence
from quiescence (southwestern edge of range).

Clarke (1958:40-45) reported T. o. ornata in all terrestrial communities
studied in Osage County; he considered the subspecies
to be characteristic of the "… cultivated-field community
…" and to be of frequent occurrence in (but not characteristic
of) the "… Oak-Walnut Hillside Forest …, Buckbrush-Sumac
…, and Prairie communities …". Brennan
(1937:345) found T. o. ornata to be equally abundant in mixed
prairie and prairie-streamside habitats in Ellis County; the subspecies
was much rarer on rocky hillsides and in the habitat surrounding
prairie ponds. Carpenter (1940:641) listed T. o. ornata
as an inhabitant of "… tall and mixed-grass prairies …"
(also in Oklahoma and Nebraska). Fitch (1958:99) found the
order of preference for habitats at the Natural History Reservation
to be grazed pasture land, woodland, open fields with undisturbed
[Pg 543]
prairie vegetation, and fallow fields with a rank growth of weeds.

At the Damm Farm the greatest number of box turtles was
collected on the pasture, especially in three areas designated in
Plate 15
as the "northwest corner," "southern ravine," and "house
pond" areas. These three areas had several features in common.
All contained ravines and rocky slopes that provided many places
of concealment (dens, burrows of larger animals, and suitable substrate
for the excavation of earthen forms). All contained water
(in ponds and intermittent streams) for most of the year; and, all
were frequented daily by cattle that left an abundant supply of
dung in which box turtles foraged. In addition, each of the three
areas contained at least one mulberry tree, under which fruit was
abundant in the months of June and July.

The relative numbers of box turtles found in different areas on
the Damm Farm were, of course, governed to some extent by my
activity in these areas and by the relative ease with which box
turtles were seen in different types of vegetational cover. Turtles
were more easily seen in the pasture (especially in sparsely
vegetated or denuded areas) where much of my field work was
done on horseback, than in the wooded areas, where excursions
were usually made on foot. It was evident, however, after mapping
known ranges and studying patterns of movement in marked turtles,
that concentrations in the three above-mentioned areas of pasture
were an indication of actual preference by turtles for the more
favorable habitat in these areas rather than the result of incomplete
sampling.

Mating takes place throughout the season of activity but is most
common in spring—soon after emergence from hibernation—and
in autumn. Turtles frequently copulated in the laboratory in spring
and autumn. Copulation was observed under natural conditions
on several occasions but only once at the Damm Farm.

Norris and Zwiefel (1950:4) saw two captive individuals of T. o.
luteola copulating on 12 August; copulation lasted two hours.
Brumwell (1940:391-2) gave the following description of mating in
T. o. ornata. A male pursued a female for nearly half an hour, first
nudging the margins of her shell and later approaching her rapidly
from the rear and hurling himself on her back in an attempt to
mount, at the same time emitting a stream of liquid from each
nostril. The liquid was presumably water; both sexes had imbibed
[Pg 544]
water in a pond just before courtship began. Brumwell suggested
that pressure on the plastron of the male had forced the water out
his nostrils. The pair remained in the coital position for 30 minutes
after the male had achieved intromission. In another instance,
Brumwell (loc. cit.) saw four males pursuing a single female, the
males exhibiting the same behavior (nudging and lunging) outlined
above. Males that attempted to mount other males were repelled
by defensive snapping of the approached male. The female also
snapped at some of the males that tried to mount her. One male
was finally successful in mounting and was henceforth unmolested
by the other males. Brumwell suggested that shell biting and
tapping may be methods of sex-recognition.

In the several instances of mating that I observed, the male,
after mounting the shell of the female (Pl. 28), gripped her, with
the first claws of his hind feet, just beneath her legs or on the skin
of the gluteal region and, with the remaining three claws, gripped
the posterior edges of her plastron. In most instances the female
secured the male's legs by hooking her own legs around them.
The coital position of T. ornata seems to differ from that of T.
carolina, at least in regard to the position of the male's legs. The
coital positions of T. carolina illustrated by Cahn (1937:94, Fig.
13) are physically impossible for T. ornata.

In T. ornata the pressure exerted on the male's legs by the female
probably impairs circulation and probably is painful to the male,
especially after coitus, when the male falls backward but is still
held by the female. The heavily developed musculature of the
legs of males may be an adaptation to strengthen the legs for this
temporary period of stress. Evans (1953:191) and Cahn and
Conder (1932:87-88) observed the hind legs of males of T. carolina
to be noticeably weakened after copulation, causing the males
to remain inactive for several hours.

Evans (op. cit.) observed 72 matings of T. carolina and divided
the process into three phases as follows: 1) circling, pushing and
biting by the male; 2) mounting (female with shell closed); and,
3) coition (female with shell open). Penn and Pottharst (1940:26)
reported that captive T. carolina in New Orleans mated chiefly
under conditions of optimum temperature (21 to 27° C.) and high
humidity; some matings took place in a pool of water. Males pushed
females about after mating, often rolling them over several times.

Because ornate box turtles observed by me were able easily to
right themselves from an inverted position on substrata of all
[Pg 545]
kinds, males left lying on their backs after copulation are probably
in no danger of perishing in this position, as was suggested by
Allard (1939) for T. carolina.

Oviducts of several females were flushed by means of a pipette
to determine whether they contained sperm. Approximately half
of the females captured in May, 1956, had sperm in their oviducts,
but females captured in June and July did not. Sperm flushed from
the oviducts were in clumps of several hundred and showed no
sign of motility a few minutes after the female was anesthetized
with chloroform. No sperm were found in the oviducts of immature
females but one female of nearly adult size was observed in
copulation with a mature male.

Thorough examination of microscopic sections of oviduct (taken
at various times in the season of activity) usually revealed a few
sperm lodged in the folds (Pl. 19, Fig. 8) of the cephalic as well
as the caudal portion of the tube, but no specialized seminal receptacles
such as occur in snakes (Fox, 1956) were present. Fertilization
without reinsemination probably occurs in T. ornata.
Ewing (1943) and Finneran (1948:126) reported that females of
T. carolina produced fertile eggs for periods of four and two years,
respectively, after being removed from all contact with males.

Testes were preserved in each month from April to October. The
following description of spermatogenesis is based chiefly on material
collected in 1955, although testes were preserved also in 1954.
Comparison of material obtained in 1954 and 1955 revealed that
spermatogenesis began earlier and was more advanced on any
given date in 1955 than in 1954.

Testes of mature individuals are pale yellow and slightly oblong.
The epididymis is ordinarily dark brown or black and contrasts
sharply with the color of the testes. Size of testes was expressed as
the average length (greatest diameter) of both testes. Testes are
smallest in April, immediately after emergence from hibernation,
and largest in early September (Pl. 20, Figs. 3-4). They are nearly
spherical when of maximum size; increase in bulk, therefore, is
relatively greater than the increase in size shown in Figure 3. They
increase in size from April until early June, recede during most of
June, and again increase in size in July and August. They remain
[Pg 546]
large from early September until hibernation is begun, becoming
only slightly smaller in late September and October.

Increase in size following emergence from hibernation may be
due in part to proliferation of the sustentacular cytoplasm. Decrease
in size in early June is correlated with the end of the period
of most active mating; maximal size is coincident with the peak of
the spermatogenic cycle in early September.

Fig. 3. Seasonal fluctuations in size (average greatest diameter) of testes in T. o. ornata as determined by examination of 40 specimens from eastern Kansas.

Spermatogenesis (refer to Pl. 19, Figs. 1-5) begins in early May
when a few spermatogonia appear in the seminiferous tubules. The
histological appearance of testes preserved in April and May is much
the same. Nuclei of Sertoli cells, which outnumber the spermatogonia,
are evident at the periphery of the tubules and the clear
cytoplasm of the cells extends into and nearly fills the lumina. The
few darkly stained spermatids that are present in April are cells
that probably were produced in the previous summer. Sperm are
present in small groups within the sustentacular cytoplasm, but
ordinarily are absent in the lumina.

[Pg 547]

Primary spermatocytes appear in the tubules from mid-May to
early June. By mid-May there are practically no sperm at any
place in the tubules. The sustentacular cytoplasm has a less compact
arrangement in late May than in April.

Spermatogenesis is well under way by mid-June; at this time,
two or three distinct layers of primary and secondary spermatocytes
are present and these cells outnumber the Sertoli cells. The lumina
are filled with cellular detritus and are no longer bordered by a
clear ring of sustentacular cytoplasm. No sperm are present.

Spermatids appear in late June and a few of them undergo metamorphosis
in early July; by mid-July, spermatids and secondary
spermatocytes are the dominant cells in the seminiferous tubules,
although spermatogonia are still active.

By late August, clusters of sperm and metamorphosing spermatids
surround the Sertoli cells; large numbers of sperm as well as
sloughed cells representing various spermatogenic stages are present
in the lumina. Secondary spermatocytes are still evident near the
periphery of the tubules but they are much less numerous than
spermatids. The germinal epithelium is still semiactive and small
groups of primary spermatocytes are present in nearly all of the
tubules.

The spermatogenic cycle is completed in the latter half of October
when most of the spermatozoa pass into the epididymides. A few
spermatozoa and spermatids remain in the seminiferous tubules
during hibernation. Although no testicular material was obtained
from hibernating turtles, comparisons of sections made in October
and April show that the germinal epithelium remains inactive from
autumn until spring. Possibly some spermiogenesis takes place in
the early phases of hibernation or in the period in late autumn
when turtles are intermittently active. It is uncertain whether
the reorganization of the sustentacular cytoplasm occurs in autumn,
in spring, or in the course of hibernation.

The seminiferous tubules of immature males are small, lack
lumina, and contain a few large but inactive spermatogonia (Pl. 19,
Fig. 6). The testes of specimens that were nearly mature contained
primary and secondary spermatocytes but lacked lumina; it was
thought that such individuals would have matured in the following
summer and bred in the following autumn.

Mature sperm were found in epididymides at all times of the year
but were most numerous in spring and autumn, the period between
[Pg 548]
spermatogenic cycles (Pl. 19, Fig. 7). Sperm expelled from the
epididymides in autumn matings are seemingly replaced by others
from the seminiferous tubules; the epididymides become much
smaller when their supply of sperm is nearly exhausted after spring
mating.

Risley (1938:304) found the testes of the common musk turtle,
Sternotherus odoratus, to be largest in August and smallest in early
May. Recession of testes in spring was coincident with the period
of active breeding; increase in size, later in the season, corresponded
to increasing spermatogenic activity and enlargement of seminiferous
tubules. Altland (1951:600-603) found the spermatogenic cycle
of Terrapene carolina to be nearly like that of Sternotherus odoratus.
Fox (1952) found that testes of garter snakes (Thamnophis sirtalis
and T. elegans) in California reached a peak of spermatogenic
activity in midsummer, regressed in the latter half of the summer,
and were inactive in winter.

The spermatogenic cycle of T. ornata as here reported, differs
in no important respect from those of Thamnophis, Sternotherus
odoratus, or Terrapene carolina, except that in T. ornata the cycle
begins and ends somewhat later in the season of activity. In most
of the lizards that have been studied (Fox, 1952:492-3), spermatogenesis
reaches a peak in spring (more or less coincident with the
mating period and with ovulation) and the germinal epithelium remains
active in winter. Sternotherus, Terrapene, and Thamnophis
are alike in completing spermatogenesis late in the season and storing
spermatozoa, in the seminiferous tubules or in the epididymides,
during hibernation.

It is noteworthy that, in the turtles and snakes mentioned above,
sperm produced in autumn are used to fertilize eggs laid in the
following year, and mating [with the exception of Thamnophis
elegans, (Fox, 1956)] occurs in both spring and autumn. It is not
definitely known in any of these instances, whether sperm resulting
from autumn or spring inseminations (or both) fertilize the eggs.
Risley (1933:693) found motile sperm in the oviducts of female
Sternotherus odoratus that had recently emerged from hibernation;
he believed that spring mating, although it commonly occurred,
was not necessary to fertilize eggs. Disadvantages, if any, of completing
spermatogenesis well in advance of ovulation seem to be
at least partly counteracted by two annual mating periods or by
mating throughout the season of activity.

[Pg 549]

The following account of oögenesis is based on examination of
preserved ovaries from 68 mature specimens. The ages of most
specimens were known, inasmuch as the specimens were used in
studies of growth as well as gametogenesis. Other data were obtained
from adult females that were dissected but not preserved,
and from immature females.

Fig. 4. Seasonal fluctuations in ovarian weight in T. o. ornata, as determined by examination of 60 specimens from eastern Kansas.

Size of ovarian follicles was determined by means of a clear
plastic gauge containing notches 5, 10, 15, 20, and 25 millimeters
wide. The number of follicles within a given size range could
be quickly determined by finding the smallest notch into which the
follicles fit. It was necessary to weigh all ovaries after preservation
since some of them had not been weighed when fresh. Since
all ovarian samples were preserved in the same manner, weights
[Pg 550]
remained relatively the same. Preserved material was lighter than
fresh by an average of 13 per cent. Follicles less than one millimeter
in diameter were not counted. Corpora lutea and corpora
albicantia were studied under a binocular dissecting microscope.
No histological studies were made of the female reproductive system.

Ovarian follicles and oviducal eggs were recorded separately for
the right and left sides. Each ovary was always kept associated
with the oviduct of the same side, but in some instances it was
not recorded whether the organs were left or right.

Ovaries ordinarily weighed most in October, March, and April,
when most females contained enlarged follicles, and least in August
and September when the supply of enlarged follicles was usually
exhausted (Figs. 4 and 5).

Fig. 5. The seasonal occurrence of enlarged ovarian follicles in females of T. o. ornata, expressed, for each month, as the percentage of total females that contained two or more follicles having diameters greater than 15 mm. Total number of females in each of the samples is shown in parentheses at the top of each bar.

The ovarian cycle begins in July or August, after ovulation has
occurred. At that time many minute follicles form on the germinal
ridges of the ovaries. On the basis of the material that I examined,
it seems that ovarian follicles either grow to nearly mature size
in the season preceding ovulation and remain quiescent over winter
or grow rapidly in the period of approximately six weeks between
spring emergence and ovulation. Altland (1951:603-5) reported
[Pg 551]
that the former condition was the usual one in T. carolina;
he suggested that possibly some of the enlarged follicles were
absorbed during hibernation.

Examination of yolks of oviducal eggs revealed that follicles
mature when they reach a diameter of 16 to 20 millimeters and a
weight of two to two and one-half grams (Pl. 20, Fig. 1).

The enlarged follicles remaining on the ovaries after ovulation
(excluding those smaller than six mm.) can be grouped according
to diameter as: large (greater than 15 mm.), medium (11 to 15
mm.), and small (six to 10 mm.). Ten females collected in the
period from June 2 to 8, after they had ovulated, all had follicles
falling in at least one of these size groups, and eight had follicles
falling in two or more of the groups. In females having enlarged
follicles of more than one of the size groups, there were several
follicles in each of two groups and no follicles, or only one follicle,
in the remaining group. Enlarged follicles represent future clutches
but whether the enlarged follicles will be ovulated in the same
season or in a later season is questionable.

Evidence found in the present study suggested that at least a
few females lay more than one clutch of eggs per year. Among 34
specimens obtained in June and July, eight (24 per cent) had
corpora lutea (or easily discernible corpora albicantia) and at least
two follicles more than 15 millimeters in diameter; in three specimens
(9 per cent) the ovaries bore fresh corpora lutea (representing
recent ovulations) and a set of older corpora lutea (representing
ovulations that had occurred several weeks previously). It was
thought that each of these eleven females (33 per cent of sample)
had produced or would have produced two clutches of eggs in the
season of its capture. The number of large follicles present after
the first set of ovulations (mean, 3.5) was fewer in most instances
than the average clutch-size (see below), indicating that second
clutches are smaller than first clutches. Smaller second clutches
were found also in T. carolina (Legler, 1958).

Further evidence for multiple clutches was the absence of enlarged
ovarian follicles in some females obtained in September.
Atretic follicles, ordinarily orange, brown, or purplish, were observed
on the ovaries of many of the females examined; in most
instances, not more than two follicles of the small or medium size
groups were atretic. Atresia was in no instance great enough to
account for the complete loss of enlarged follicles.

Further study probably will show that many of the females laying
[Pg 552]
in May and early June lay again before the end of July, and that
eggs in the oviducts of females captured in the latter month frequently
represent second clutches. Under favorable conditions,
eggs laid by the end of July would have a good chance of hatching
before the advent of cold weather in autumn; turtles hatching too
late to escape from the nest could burrow into its sides and
probably escape freezing temperatures.

Cagle's findings concerning Pseudemys scripta (1950:38) and
Chrysemys picta (1954:228-9) suggest that these species lay more
than one clutch per season, at least in the southern parts of their
ranges. Carr (1952) indicated that multiple layings were known
in most species of marine turtles (families Dermochelydae and
Chelonidae) and strongly suspected in other species. Other turtles
recorded to have produced multiple clutches in a single season
(based chiefly on captive specimens or cultured populations) include:
the starred tortoise, Geochelone elegans (Deraniyagala,
1939:287); the Asiatic trionychid, Lissemys punctata (op. cit.:304);
the diamond-backed terrapin, Malaclemys terrapin (Hildebrand
and Prytherch, 1947:2); and the Japanese soft-shelled turtle, Trionyx
japonicus (Mitsukuri, 1895, cited by Cagle, 1950:38).

There is a marked alternation of ovarian activity in T. ornata, one
ovary being more active than its partner in a given season. The less
active ovary is more active than its partner in the following season.
For example, a specimen killed in July had four corpora lutea on
the right ovary and two on the left and there were five enlarged
follicles (of the medium size group), representing the next set of
eggs to be ovulated, four on the left ovary and one on the right.
Similar alternation of ovarian activity was observed, to a greater or
lesser extent, in nearly all of the females examined. Many subadult
females that were approaching their first breeding season (as
evidenced by the presence of large ovarian follicles but no indication
of former ovulation) had but one active ovary. This may account
in part for the tendency of small, young females to lay
clutches smaller than average. One ovary may become senile in
old females before its partner does; this may explain the occasional
absence or atrophy of one ovary in large females that I have
examined.

In all the specimens examined, it was evident that ovulation had
occurred or would occur in two successive seasons. Senile or young
females might, however, be expected to skip a laying season if only
one ovary was functioning.

After ovulation, the collapsed follicle assumes a cuplike shape
[Pg 553]
and becomes a glandular corpus luteum (Pl. 20, Fig. 2). Corpora
lutea are approximately eight millimeters in diameter and are easily
discernible at least until the eggs are laid; they are somewhat less
distinct after preservation. Corpora lutea undergo rapid involution
following oviposition and, after two to three weeks, are little more
than small puckerings on the ovarian epithelium. At this stage
they are properly referred to as corpora albicantia and are discernible
only after careful examination of the ovary under low
magnification. Corpora albicantia remain on the ovary until April
of the year following ovulation but disappear in May and are never
present after the new set of eggs is ovulated. Ovaries of some sub-adults
(that would have laid first in the season following capture)
contained enlarged follicles and, but for their lack of corpora lutea
and corpora albicantia, were indistinguishable from those of older,
fully mature females.

Altland (1951:605-610) gave a histological description of the
corpus luteum of Terrapene carolina. Corpora lutea were glandular
and filled with lipoidal material until the eggs were laid. Atresia
of corpora lutea began when eggs were laid, was completed by mid-August,
and was coincident with atresia of large follicles that did
not undergo ovulation. Altland did not describe the gross external
appearance of the corpus albicans.

The corpus luteum of oviparous reptiles seems to be closely associated
with the intrauterine life of the eggs and, in viviparous
reptiles, it may be an important factor in maintaining optimum
gestational environment; however, its functions in all reptiles are
poorly understood (Miller, 1948:200-201).

Information gleaned from records of gravid females and known
dates of nesting suggests that eggs are retained in the oviducts two
to three weeks before laying. Once they are ovulated, the eggs
are exposed to but few hazards until laid; counts of corpora lutea
are an accurate indication of the number of eggs laid. In the gravid
females examined by me, number of corpora lutea on the ovaries
was equal, in all but one instance, to the number of oviducal eggs.
In the single instance in which an extra corpus luteum was found,
one egg had probably been laid before the specimen was captured.
The high incidence of correspondence between counts of corpora
lutea and counts of oviducal eggs indicates also that T. ornata deposits
the entire complement of oviducal eggs at one time, not
singly or in smaller groups.

Extrauterine migration of ova, whereby eggs from one ovary pass
into the oviduct of the opposite side, is of common occurrence in
[Pg 554]
T. ornata and is known to occur also in T. carolina, Chrysemys
picta, Emydoidea blandingi, Pseudemys scripta, Cnemidophorus
sexlineatus, and in several mammals (Legler, 1958). This ovular
migration may serve to redistribute eggs to the oviducts when the
ovaries are functioning at unequal rates.

The eggs acquire shells soon after they enter the oviducts. No
shell-less eggs were found in oviducts but several specimens of
T. ornata had oviducal eggs, the thin, parchmentlike shells of which
lacked the outer calceous layer; in these specimens the corpora
lutea were fresh, probably not more than two days old. Eggs that
had remained in the oviducts longer had a calceous layer on the
outside of the shell. Eggs having incompletely developed shells
were successfully incubated in the laboratory. Cagle (1950:38)
found shelled but yolkless eggs in the oviducts of several Pseudemys
scripta but found no yolkless eggs in nests. No yolkless eggs were
found in specimens of T. ornata in the course of the present study.

The uterine portion of the oviducts becomes darkened (pale
gray to intense black) in the breeding season. Darkening of oviducts
seemed to coincide with the period when eggs were in the
oviducts and it persisted for a variable length of time after the
eggs were laid. Oviducts of immature females were ordinarily pale.

Ornate box turtles nest chiefly in June. Some females nest as
early as the first week of May or as late as mid-July but the nesting
season reaches its peak in mid-June. Eggs nearly ready to be laid
were in oviducts (determined by bimanual palpation in the field
or by dissection in the laboratory) of many females captured in
June; nearly half of the records so obtained were in the second
week of that month. Early records of shelled oviducal eggs were
April 25 (specimen from Ottawa County, Oklahoma), May 5, and
May 22. The two latest records are for females retaining oviducal
eggs on July 2 and 11. Known dates for nesting of free-living females
were distributed rather evenly through the month of June.
It is worthy of note that all (four) of the nestings known to occur
in July were by captive females. Females of T. ornata, like those
of some other turtles (Cagle and Tihen, 1948; Risley, 1933:694),
seem to retain their eggs until conditions are suitable for nesting.
Most of the reports in the literature of nesting after mid-July represent
records for captive females.

[Pg 555]

Nests of T. o. ornata were so well-concealed that they were difficult
to find even when a gravid female had been followed to the
approximate location by means of a trailing thread. Females
spend one to several days seeking a site for the nest, usually traveling
a circuitous route within a restricted area. Movements of
nest-seeking females were more extensive than those of males and
non-gravid females observed in the same periods.

Activities of one gravid female, typical in most respects of the
activities of several other gravid females observed (for periods
of one to 23 days) at the Damm Farm, illustrate pre-nesting behavior
(Fig. 29). A trailer was attached to the female on the
morning of June 7. She was recovered early on the following
afternoon; her movements in the elapsed period had been restricted
to a small, deep, ravine 150 feet long and 20 to 30 feet wide. She
had traversed each edge of the ravine at least once and had
crossed it six or seven times, keeping mostly to areas on the upper
parts of south—or west—facing slopes where vegetation was sparse
or lacking. In six places she had dug into the ground, probably
to test the suitability of the soil for nesting. In three places she
dug beneath rocks that jutted out from the bank, and in two places
merely scratched away the upper crust of soil. Her most recent
attempt at digging (probably late the previous evening or in early
morning on the day of her capture) consisted of a flask-shaped
cavity that, but for the lack of eggs and a covering of earth, was like
a completed nest (Pl. 21, Fig. 1). The cavity was 55 millimeters
deep, 80 millimeters wide at the bottom, and 60 millimeters wide
at the opening. For several inches about the opening the earth
was slightly damp. That piled on the rim of the opening was
of the consistency of thick mud, indicating that the female had
voided fluid first on the surface of the earth and again inside the
cavity to soften the soil. Subsequently during eight days her activities
were similar but not so extensive as on the day described
above. It was determined by daily palpation that she laid her eggs
somewhere in the general area of the ravine on June 15 but the
nest could not be found.

No completed nests containing eggs were discovered at the
Damm Farm but the locations of several robbed nests and partly
completed nests provided some information on preferred sites.
The nests found were on bare, well-drained, sloping areas and
were protected from erosion by upslope clumps of sod or rocks.
[Pg 556]
The nest cavity illustrated in Plate 21 was at the edge of the sod-line
on the upper lip of the west-facing bank of a ravine. One
nest had been excavated in a shallow den beneath an overhanging
limestone rock. Three nests were on west- or south-facing slopes
and one was on the north-facing bank of a ravine. Box turtles
presumably select bare areas for nesting because of the greater
ease of digging. One female at the Damm Farm was thought to
have laid her eggs in a cultivated field and William R. Brecheisen
told me he discovered two nests in a wheat field being plowed in
July, 1955.

The repeated excavation of trial nest cavities presumably exhausts
the supply of liquid in the female's bladder. Frequent
imbibing of water is probably necessary if the search for a nesting
site is continued for more than a day or two. Standing water was
usually available in ponds, ravines, ditches, and other low areas at
the Damm Farm in June. Nesting in June, therefore, is advantageous
not only because of the greater length of time provided for incubation
and hatching but also because of the amount of water
available for drinking. Females can probably be more selective in
the choice of a nesting site if their explorations are not limited by
lack of water.

Females of T. ornata, in all instances known to me, began excavation
of their nests in early evening and laid their eggs after dark;
Allard (1935:328) reported the same behavior for T. carolina.

William R. Brecheisen, on July 22, 1955, at his farm, two miles
south and one mile west of Welda, Anderson County, Kansas, observed
that a large female began digging a nest in an earth-filled
stock tank at 6:00 P. M. At first she moved her body about on the
surface of the earth, loosening it and pushing it aside with all four
legs, making a depression approximately two inches deep and large
enough to accommodate her body. At 7:30 P. M. she began digging
alternately with her hind feet at the bottom of the depression.
Digging continued until 10:00 P. M., at which time the nest cavity
was three inches deep, and three inches in diameter, with a smaller
opening at the top. Six eggs were laid in the next half-hour.
Covering of the nest probably took more than one hour but observations
were terminated after the final egg was laid. By the following
morning the nest-site had been completely covered and was no
different in appearance from the rest of the earthen floor of the
tank. (Brecheisen observed more of the nesting than anyone else
[Pg 557]
has recorded and I am obliged to him for permission to abstract,
as per the above paragraph, the notes that he wrote on the matter.)

A nest made by a captive female at the Reservation was of normal
proportions except for an accessory cavity that opened from the
neck of the nest, immediately below the surface of the ground.
This smaller cavity contained a single egg. This peculiar nest may
have resulted from the efforts of two different females since several
were kept in the same outdoor pen.

Ten adult females were kept in an outdoor cage in the summer of
1955. The cage was raised off the ground on stilts and its floor was
covered with 12 inches of black, loamy soil. A small pan of water
was always available in the cage and the turtles were fed greens,
fruit, and table scraps each evening. Nesting activity was first
noted on June 21, when one of the females was digging a hole in a
corner of the enclosure. She dug with alternate strokes of her fully-extended
hind legs in the manner described (Legler, 1954:141) for
painted turtles (Chrysemys picta bellii). Nevertheless, digging was
much less efficient than in Chrysemys, because of the narrow hind
foot of the female T. ornata; approximately half of the earth removed
by any one stroke rolled back into the nest or was pulled
back when she reinserted her leg. The female stopped digging
when I made sudden movements or held my hand in front of her.
Digging continued for approximately 45 minutes; then the female
moved away and burrowed elsewhere in the cage. The nest cavity
that she left was little more than a shallow depression. Three
other females were digging nests early in the evening on July 3,
5, and 8; in each of these instances the female stopped digging to
eat when food was placed in the cage and completed the nesting
process, unobserved, later in the evening. In each instance where
nest-digging by captive females was observed, the hind quarters
of the female rested in a preliminary, shallow depression, and the
anterior end of the body was tilted upward at an angle of 20 to
30 degrees. In late June and early July several eggs were found,
unburied, on the floor of the cage and in the pan of water.

The excavation of a preliminary cavity by captive females may
not represent a natural phenomenon. Allard (1935) made no
mention of it in his meticulous description of the nesting process
in T. carolina. It is worthy of mention, however, that Booth
(1958:261) reported the digging of a preliminary cavity by a
captive individual of Gopherus agassizi.

[Pg 558]

The number of eggs in 23 clutches ranged from two to eight
(mean, 4.7 ± 1.37 σs]); clutches of four, five, and six eggs were
most common, occurring in 18 (78 per cent) instances. The tendency
for large females to lay more eggs than small females
(Fig. 6) was not so pronounced
as that reported by Cagle (1950:38) for Pseudemys scripta. The
small size of T. ornata, in comparison with other emyid turtles,
seemingly limits the number of eggs that can be accommodated
internally. The number of eggs per clutch in T. carolina
[2 to 7, average 4.2, Allard (1935:331)], is nearly the same as that
of T. ornata.

Fig. 6. The relation of plastral length to number of eggs laid by 21 females of T. o. ornata from eastern Kansas.

Shells of the eggs are translucent and pinkish or yellowish
when the eggs are in the oviducts. After several days outside
the oviducts the shells become chalky-white and nearly opaque.
Eggs incubated in the laboratory retained the pinkish color somewhat
longer than elsewhere on their under-surfaces, which were
in contact with moist cotton, but eventually even this part of the
shell became white. Infertile eggs remained translucent and
eventually became dark yellow, never becoming white; they could
be distinguished from fertile eggs on the basis of color alone.
Shells of infertile eggs became brittle and slimy after several weeks.

The outer layer of the shell of a freshly laid egg is brittle and
cracks when the egg is dented. After a few days, when the eggs
begin to expand, the shell becomes flexible and has a leathery
texture. The shell is finely granulated but appears smooth to the
unaided eye. The granulations are approximately the same as
those illustrated by Agassiz (1857:Pl. 7, Fig. 18) for T. carolina.

Eggs are ellipsoidal. Data concerning size and weight (consisting
of mean, one standard deviation, and extremes, respectively)
taken from 42 eggs (representing 9 clutches) within 24 hours after
they were laid, or dissected from oviducts, are as follows: length,
36.06 ± 2.77 (31.3-40.9); width, 21.72 ± 1.04 (20.0-26.3); and
weight, 10.09 ± 1.31 (8.0-14.3). There was a general tendency
[Pg 559]
for smaller clutches to have larger eggs; the largest and heaviest
were in the smallest clutch (two eggs) and the smallest were in
the largest clutch (eight eggs). Risley (1933:697) reported such
a correlation in Sternotherus odoratus, as did Allard (1935:331)
in T. carolina. Measurements in the literature of the size of eggs
of T. ornata suggest a width greater than that stated above, probably
because some eggs already had begun to expand when measured.

Eggs of T. ornata expand in the course of incubation, as do
other reptilian eggs with flexible shells, owing to absorption of
water. In the laboratory, 48 eggs increased by an average of approximately
three grams in weight and three millimeters in width
over the entire period of incubation; increase in width coincided
with decrease in length. Cotton in incubation dishes was kept
moist enough so that some water could be squeezed from it. When
the cotton was constantly moist, eggs showed a fairly steady expansion
from the first week of incubation until hatching. The
process could be reversed by allowing the cotton to dry. Eggs
that were allowed to dry for a day or more became grossly dented
or collapsed. Eggs at the periphery of the incubation dish were
ordinarily more seriously affected by drying than were those at
the center or in the bottom of the dish. A generous re-wetting
of desiccated eggs and cotton caused the eggs to swell to their
original proportions within 24 hours. Recessions occurred, however,
even in the clutches that received the most nearly even amount of
moisture. Increases in weight and size seemed to reach a peak
in the middle of the incubation period and again immediately before
hatching. Infertile eggs expanded in the same manner as
fertile eggs in the first week or two of incubation, but thereafter
gradually regressed in bulk or failed to re-expand after temporary
periods of dryness. Fertile eggs that were in good condition had
a characteristically turgid, springy feel and could be bounced
off a hard surface.

Temporary lack of moisture usually did not kill embryos; prolonged
dryness, combined with high temperatures, probably could
not be tolerated. Lynn and Ullrich (1950), by desiccating the
eggs of Chrysemys picta and Chelydra serpentina, produced abnormalities
in the young ranging from slight irregularities of the
shell to eyeless monstrosities; eggs desiccated in the latter half of
incubation produced a higher percentage of abnormal young than
eggs that were desiccated earlier.

[Pg 560]

In 1956, three fertile eggs, from clutches that were at different
stages of incubation, were immersed in water for 48 hours. The
eggs rested on the bottom of the bowl in the same position in
which they had been placed in the incubation dishes; when turned,
they returned invariably to the original position. The embryos
in two of the eggs (one and 27 days old at the time of immersion)
were still living ten days after the eggs were removed from the
water; the embryo in the remaining egg (21 days old at the time
of immersion) was dead. Eggs immersed in water increased in size
and weight at the same rate as eggs in incubation dishes, indicating
that absorption of water probably operates on a threshold
principle, the amount absorbed being no more than normal even
under wet conditions.

Natural nests usually are in well-drained areas, but water probably
stands in some nests for short periods after heavy rains. Provided
the nest cavity itself is not damaged, water in the nest is
probably more beneficial than harmful to the eggs; however, nests
that are inundated during floods probably have little chance of
survival.

Eggs were examined by transmitted light in the course of incubation.
At the time of laying (or removal from oviducts) no
embryonic structures were discernible even in eggs that had been
retained in the oviducts of captive females some weeks past the
normal time of laying; a colorless blastodisc could be seen if eggs
were opened. Embryonic structures first became visible at eight
to ten days of incubation; at this time vascularization of the blastodisc
was evident and the eyes appeared as dark spots. Heart
beats were observed in most embryos by the fifteenth day but
were evident in a few as early as the tenth day. The pulse of a
fifteen-day-old embryo averaged 72 beats per minute at a temperature
of 30 degrees. Embryos at fifteen days, measured in a
straight line from cephalic flexure to posteriormost portion of body,
were approximately nine to ten millimeters long and at 22 days
were 14 millimeters long. At approximately 35 days the eggs
became dark red; embryonic structures were discernible thereafter
only in eggs that had embryos situated at one end, close to
the shell.

Incubation periods for 49 eggs (representing 12 clutches) kept
in the laboratory ranged from 56 to 127 days, depending on the
temperature of the air during the incubation period. In 1955, eggs
[Pg 561]
were kept at my home in Lawrence where air temperatures were
uncomfortably hot in summer and fluctuations of 20 degrees
(Fahrenheit) or more in a 24-hour period were common. The following
summer eggs were kept in my office at the Museum where
temperatures were but slightly cooler than in my home and subject
also to wide variation. In 1957 this part of the Museum was air-conditioned
and kept at approximately 75 degrees. The greater
lengths of incubation periods at lower temperatures are shown in
Table 1. Risley (1933:698) found the incubation period of Sternotherus
odoratus to be longer at lower temperatures; corresponding
observations were made by Allard (1935:332) and Driver (1946:173)
on the eggs of Terrapene carolina. Cagle (1950:40) and
Cunningham (1939) found no distinct differences in length of incubation
period for eggs of Pseudemys scripta and Malaclemys
terrapin, respectively, at different temperatures within the range
tolerated by the eggs.

Most nests observed in the field were in open situations where
they would receive the direct rays of the sun for at least part of
the day; the shorter average incubation periods (59 and 70 days,
respectively), observed in 1955 and 1956, therefore, more nearly
reflect the time of incubation under natural conditions than does
the excessively long period (125 days at 75 degrees) observed in
1957 under cooler, more nearly even temperatures.

Sixty-five days seems to be a realistic estimate of a typical incu
[Pg 562]bation
period under natural conditions; eggs laid in mid-June
would hatch by mid-August. Even in years when summer temperatures
are much cooler than normal, eggs probably hatch by the
end of October. Hatchlings or eggs would have a poor chance
of surviving a winter in nests on exposed cut-banks or in other
unprotected situations. Overwintering in the nest, hatchlings might
survive more often than eggs, since hatchlings could burrow into
the walls and floor of the nest cavity. Unsuitable environmental
conditions that delay the nesting season and retard the rate of
embryonic development may, in some years, be important limiting
factors on populations of ornate box turtles.

In areas where T. ornata and T. carolina are sympatric (for example,
in Illinois, Kansas, and Missouri) the two species occupy
different habitats, ornata preferring open grassland and carolina
wooded situations. Under natural conditions, the average incubation
periods of these two species can be expected to differ, T. carolina
having a somewhat longer period due to lower temperatures
in nests that are shaded. In the light of these speculations, the remark
of Cahn (1937:102)—that T. ornata nested later in the season
(in Illinois) and compensated for this by having a shorter incubation
period—is understandable.

The range of temperatures tolerated by developing eggs probably
varies with the stage of embryonic development. When temperatures
in the laboratory were 102 to 107 degrees Fahrenheit for approximately
eight hours, due to a defect in a thermostat, the young
in two eggs of T. ornata, that had begun to hatch on the previous
day, were killed, as were the nearly full-term embryos in a number
of eggs of T. carolina (southern Mississippi) kept in the same
container. A five-day-old hatchling of T. ornata, kept in the same
container, survived the high temperatures with no apparent ill effects.
Cagle (1950:41) found that eggs of Pseudemys scripta
could not withstand temperatures of 10 degrees for two weeks nor
would they survive if incubated at 40 degrees. Cunningham (1939)
reported that eggs of Malaclemys terrapin could not survive prolonged
exposure to temperatures of 35 to 40.6 degrees but tolerated
temporary exposure to temperatures as high as 46 degrees.

In the summer of 1955, a clutch of three eggs, all of which contained
nearly full-term embryos, was placed in a refrigerator for
48 hours. The temperature in the refrigerator was maintained
at approximately 4.5 degrees; maximum and minimum temperatures
for the 48 hour period were 2.8 and 9.5 degrees, respectively. When
the eggs were removed from the refrigerator they showed gains in
[Pg 563]
weight and increases in size comparable to eggs, containing embryos
of the same age, used as controls. The experimental eggs
began to hatch two days after they were removed to normal temperatures—approximately
24 hours later than the controls.

In the late stages of incubation, the outer layer of the shell becomes
brittle and is covered with a mosaic of fine cracks or is
raised into small welts. Several days before hatching, movements
of the embryo disturb the surface of the shell and cause the outer
layer to crumble away, especially where the head and forequarters
of the embryo lie against the shell. Some embryos could be seen
spasmodically thrusting the head and neck dorsally against the
shell.

The role of the caruncle in opening the shell seems to vary
among different species of turtles. Cagle (1950:41) reported that
it was used only occasionally by Pseudemys scripta; Allard (1935:332)
thought that it was not used by Terrapene carolina; and, the
observations of Booth (1958:262) and Grant (1936:228) indicate
that embryos of Gopherus agassizi use the caruncle at least in the
initial rupturing of the shell.

In the three instances in which hatching was closely observed
in T. ornata, the caruncle made the initial opening in the shell;
claws of the forefeet may have torn shells in other hatchings that
were not so closely observed. In all observed instances, the shell
was first opened at a point opposite the anterior end of the embryo.
The initial opening had the appearance of a three-cornered tear.
A quantity of albuminous fluid oozed from eggs as soon as the shells
were punctured.

The initial tear is enlarged by lateral movements of the front
feet, and later the hind feet reach forward and lengthen the tear
farther posteriorly. In many instances a tear develops on each
side and the egg has the appearance of being cleft longitudinally.
The young turtle emerges from the anterior end of the shell or backs
out of the shell through a lateral tear.

The process of hatching, from rupture of shell to completion of
emergence, extended over three to four days in the laboratory.
Many hatchlings from time to time crawled back into the shell over
a period of several days after hatching was completed. In a clutch
of eggs kept in a pail of earth, by William R. Brecheisen, eight days
elapsed between onset of hatching and appearance of the first
hatchling at the surface.

A nest in an outdoor pen at the Reservation was discovered in
[Pg 564]
early October. The cap had been recently perforated and the
hatchlings had escaped. One of them, judged to be approximately
two weeks old, was found in a burrow nearby. The cavity of the
nest appeared to have been enlarged by the young. The eggs were
probably laid in early July. Emergence of young from the nest
had been delayed for a time after hatching, until rain softened the
ground in late September and early October.

Eggs were incubated in the laboratory at more nearly optimum
temperature and humidity than were eggs in natural nests. Percentage
of prenatal mortality probably was lower in laboratory-incubated
eggs than in those under natural conditions.

Of sixty eggs studied in the laboratory, 45 (75 per cent)
were fertile; 36 (80 per cent) of the fertile eggs (those in
which the blastodisc was at some time discernible by transmitted
light) hatched successfully. In six clutches all the eggs were
fertile and five of these clutches hatched with 100 per cent success.
One clutch contained eggs that were all infertile and another
clutch had four infertile eggs and two fertile eggs that
failed to hatch. Among nine fertile eggs that failed to survive,
four casualties occurred in the late stages of incubation or after
hatching had begun, indicating that these are probably critical periods.

Fertility of eggs was not correlated with size or age of female,
with size of clutch, or with size of egg. Eggs laid in the laboratory
had higher rates of infertility and prenatal mortality than did eggs
dissected from oviducts. Handling of eggs in removing them from
nests to incubation dishes, after embryonic development had begun,
might have been responsible for reduced viability (Table 2).

[Pg 565]

Assuming that 4.7 eggs are laid per season, that all eggs are
fertile and all hatch, that all young survive to maturity, that half
the hatchlings are females, and that females first lay eggs in the
eleventh year, the progeny of a single mature female would number
699 after twenty years. Considering that infertility and prenatal
mortality eliminate approximately 40 per cent of eggs laid
(according to laboratory findings) the average number of surviving
young per clutch would be 2.8 and the total progeny, after 20
years, would be 270, provided that only one clutch of eggs was
laid per year. But it is thought that, on the average, one third
of the female population produces two clutches of eggs in a single
season. If the second clutch contains 3.5 eggs (resulting in 2.1
surviving young when factors of infertility and prenatal mortality
are considered), the progeny of a single female, after 20 years,
would number approximately 380. Postnatal mortality reduces
the progeny to a still smaller number.

The small number of eggs laid each year and the long period
required to reach sexual maturity make the reproductive potential
of T. ornata smaller than that of the other turtles of the Great
Plains, and much smaller than nearly any of the non-chelonian
reptiles of the same region.

The total span of reproductive years is difficult to determine;
I am unable to ascertain the age of a turtle that has stopped growing.
No clearly defined external characteristics of senility were
discovered in the populations studied. A male that I examined
had one atrophied testis. In another male both testes were
shrunken and discolored and appeared to be encased by fibrous
tissue. Both males were large, well past the age of regular growth,
and had smoothly worn shells. Several old females had seemingly
inactive ovaries. Reproductive processes probably continue
throughout life in most members of the population, although possibly
at a somewhat reduced rate in later life.

Young box turtles became active and alert as soon as they
hatched, and remained so until low temperatures induced quiescence.
If sand or soil was available, hatchlings soon burrowed into
[Pg 566]
it and became inactive. Covering containers with damp cotton
also induced inactivity; the hatchlings usually made no attempt to
burrow through the confining layer. Desire to feed varied in
hatchlings of the same brood and seemed not to be correlated with
retraction of the yolk sac or retention of the caruncle. Some
hatchlings actively pursued mealworms; on subsequent feedings
they learned to associate my presence with food and eagerly took
mealworms from forceps or from my hand. Meat, vegetables, and
most other motionless but edible objects were ignored by hatchlings
but some individuals learned to eat meat after several forced feedings.
Hatchlings that regularly took food in the first month of life
ordinarily grew faster than hatchlings that did not eat. Many of
the hatchlings in the laboratory showed no areas of new epidermal
growth on the shell in the time between hatching and first (induced)
hibernation.

The proportions of the shell change somewhat in the first few
weeks of life. At hatching the shell may be misshapen as a result
of confinement in the egg. Early changes in proportions of the
shell result from expansion—widening and, to a lesser degree,
lengthening of the carapace—immediately after hatching. Subsequent
retraction or rupture of the yolk sac and closure of the navel
are accompanied by a decrease in height of shell and slight, further
widening of the carapace.

The yolk sac retracts mainly between the time when the egg
shell is first punctured and the time when the turtle actually emerges
from the shell. When hatching is completed, the yolk sac usually
protrudes no more than two millimeters, but in some individuals
it is large and retracts slowly over a period of several days.

One individual began hatching on November 11 and was completely
out of the egg shell next day; the yolk sac was 15 millimeters
in diameter, protruded six millimeters from the umbilical opening,
and hindered the hatchling's movements. The sac broke two days
later, smearing the bottom of the turtle's dish with semifluid yolk.
The hatchling then became more active. Twenty-six days later the
turtle was still in good condition and its navel was nearly closed.
A turtle that hatched with a large yolk sac in a natural nest possibly
would benefit, through increased ease of mobility, if the yolk sac
ruptured.

A recently hatched turtle was found at the Reservation in October,
[Pg 567]
1954, and was kept in a moist terrarium in the laboratory
where it died the following May. The turtle was sluggish and ate
only five or six mealworms while in captivity; no growth was detectable
on the laminae of the shell. Autopsy revealed a vestige
of the retracted yolk sac, approximately one millimeter in diameter,
on the small intestine.

The navel ("umbilical scar") of captive hatchlings ordinarily
closed by the end of the second month but in three instances remained
open more than 99 days. The position of the navel is
marked by a crescent-shaped crease, on the abdominal lamina,
that persists until the plastron is worn down in later years
(Pl. 24, Fig. 1).

Fig. 7. A hatchling of T. o. ornata
(× 2) that still retains the caruncle ("egg tooth"). A distinct boss will remain
on the maxillary beak after the caruncle is shed.

The caruncle ("egg tooth") (Fig. 7) remains attached to
the horny maxillary beak for a variable length of time; 93 per
cent of the live hatchlings kept in the laboratory retained the
caruncle on the tenth day, 71 per cent on the twentieth day,
and only 10 per cent on the thirtieth day of life. Few individuals retained
the caruncle when they entered hibernation late in November, and none
retained it upon emergence from hibernation. Activities in the first few days
or weeks of life influence the length of time that the caruncle is
retained; turtles that begin feeding soon after hatching probably
lose the caruncle more quickly than do those that remain quiescent.
The caruncles of some laboratory specimens became worn before
finally dropping off. Almost every caruncle present after 50 days
could be flicked off easily with a probe or fingernail. The initiation
of growth of the horny maxillary beak probably causes some loosening
of the caruncle. The caruncle may aid hatchlings in escaping
from the nest.

After the caruncle falls off, a distinct boss remains, marking its
former place on the horny beak (Pl. 25, Fig. 1); this boss is gradually
obliterated over a period of weeks by wear and by differential
growth, and is seldom visible in turtles that have begun their first
full year of growth. The "first full year of growth" is here considered
to be the period of growth beginning in the spring after hatching.

[Pg 568]

Growth of ornate box turtles was studied by measuring recaptured
turtles in the field, by periodically measuring captive hatchlings
and juveniles, and by measuring growth-rings on the epidermal
laminae of preserved specimens. Studies of growth-rings provided
by far the greatest volume of information on growth, not only for
the years in which field work was done, but for the entire life of
each specimen examined.

It was necessary to determine the physical nature of growth-rings
and the manner in which they were formed before growth
could be analyzed. Examination of epidermal laminae on the shell
of a box turtle reveals that each has a series of grooves—growth-rings—on
its surface. The deeper grooves are major growth-rings;
they occur at varying distances from one another and run parallel
to the growing borders of the lamina. Major growth-rings vary
in number from one to 14 or more, depending on the age of the
turtle (Pl. 22). In juvenal turtles and in young adults, major
growth-rings are distinct and deep. Other grooves on the shell—minor
growth-rings—have the same relationship to the borders
of the laminae but are shallower and less distinct than major
growth-rings. One to several minor growth-rings usually occur
on each smooth area of epidermis between major growth-rings.
As the shell of an adult turtle becomes worn, the minor growth-rings
disappear and the major rings become less distinct. Both
sets of rings may be completely obliterated in old turtles but the
major rings usually remain visible until several years after puberty.

In cross section, major growth-rings are V- or U-shaped. The
inner wall of each groove is the peripheral edge of the part of the
scute last formed whereas the outer wall represents the inner edge
of the next new area of epidermal growth. The gap produced
on the surface of the lamina (the open part of the groove) results
from cessation of growth at the onset of
hibernation. Minor growth-rings
are shallow and barely discernible in cross-section (Fig. 8).
It may therefore be understood that growth-rings are compound
in origin; each ring is formed in part at the beginning of hibernation
and in part at the beginning of the following growing season.

The few publications discussing growth in turtles express conflicting
views as to the exact mode of growth of epidermal laminae.
Carr (1952:22) briefly discussed growth of turtle scutes in general
and stated that eccentric growth results from an entirely new
[Pg 569]
laminal layer forming beneath, and projecting past the edges of the
existing lamina. Ewing (1939) found the scutes of T. carolina to
be the thickest at the areola and successively thinner in the following
eight annual zones of growth; parts of scutes formed subsequent
to the ninth year varied irregularly in thickness. He
stated that epidermal growth took place at the margins of the
laminae rather than over their entire under-surfaces.

It is evident that the mode of scutular growth described by
Carr (loc. cit.) applies to emyid turtles that shed the epidermal
laminae more or less regularly (for example, Chrysemys and
Pseudemys). In these aquatic emyids a layer of the scute, the
older portion, periodically becomes loose and exfoliates usually
in one thin, micalike piece; since the loosened portion of the scute
corresponds in size to the scute below, it must be concluded that
a layer of epidermis is shed from the entire upper surface of the
scute, including the area of new epidermal growth. Box turtles
ordinarily do not shed the older parts of their scutes; the areola
and successively younger portions of the lamina remain attached
to the shell until worn off. The appearance of a single unworn
scute, especially one of the centrals or the posterior laterals, closely
resembles a low, lopsided pyramid.

Examination of parasagittal sections of scutes revealed that they
were composed of layers, the number of layers varying with the
age of the scute. A scute from a hatchling consists of one layer. A
scute that shows a single season of growth has two layers; a new
layer is added in each subsequent season of growth. Stratification
is most evident in the part of the scute that was formed in the first
three or four seasons and becomes increasingly less distinct in newer
parts of the scute. It may further be understood that scutes grow
in the manner described by Carr (loc. cit.).

When the epidermal laminae are removed, a sheet of tough, pale
grayish tissue remains firmly attached to the bones of the shell beneath.
This layer probably includes, or consists of, germinal epithelium.
Contrasting pale and dark areas of the germinal layer
correspond to the pattern of markings on the scute removed.

Fig. 8. The second central scute from a juvenal T. o. ornata (KU 16133) in its third full season of growth. A) Entire scute from above (× 2½); dashed line shows portion removed in parasagittal section. B) Diagonal view of section removed from scute in "A" (× 43∕8, thickness greatly exaggerated) showing layers of epidermis formed in successive seasons of growth. Each layer ends at a major growth-ring (M 1-3) that was formed during hibernation; minor growth-rings (m), formed in the course of the growing season, do not result from the formation of a new layer of epidermis. Note the granular texture of the areola (a); the smooth zone between the areola and M1 shows amount of growth in the season of hatching.

Growth of epidermal laminae is presumably stimulated by growth
of the bony shell. As the bone grows, the germinal layer of the
epidermis grows with it. When growth ceases at the beginning of
hibernation, the thin edges of the scutes are slightly down-turned
where they enter the interlaminal seams (Fig. 8). When growth
is resumed in spring, the germinal layer of the epidermis, rather
than continuing to add to the edge of the existing scute, forms an
[Pg 570]
entirely new layer of epidermis. The new layer is thin and indistinct
under the oldest part of the scute but becomes more distinct
toward its periphery. Immediately proximal to the edge of the
scute, the new layer becomes greatly thickened, and, where it
passes under the edge, it bulges upward, recurving the free edge of
the scute above. At this time the formation of a major growth-ring
is completed. The newly-formed epidermis, projecting from under
the edges of the scute, is paler and softer than the older parts of the
scute; the presence or absence of areas of newly formed epidermis
[Pg 571]
enables one to determine quickly whether a turtle is growing in the
season in which it is captured. There is little actual increase in
thickness of the scute after the first three or four years of growth.
The epidermal laminae are therefore like low pyramids only in appearance.
This appearance of thickness is enhanced by the contours
of bony shell which correspond to the contours of the scutes.

Minor growth-rings differ from major growth-rings in appearance
and in origin. Ewing (op. cit.: 91) recognized the difference
in appearance and referred to minor growth-rings as "pseudoannual
growth zones." Minor growth-rings result from temporary cessations
of growth that occur in the course of the growing season, not
at the onset of hibernation. They are mere dips or depressions in
the surface of the scute. The occurrence of minor growth-rings
indicates that interruptions in growth of short duration do not result
in the formation of a new layer of epidermis. Slowing of
growth or its temporary cessation may be caused by injuries, periods
of quiescence due to dry, hot, or cold weather, lack of food,
and possibly by physiological stress, especially in females, in the
season of reproduction. Minor growth-rings that lie immediately
proximal to major growth-rings (Pl. 22, Fig. 2), are the result of
temporary dormancy in a period of cold weather at the end of a
growing season, followed by nearly normal activity in a warmer
period before winter-long hibernation is begun. Cagle (1946:699)
stated that sliders (Pseudemys scripta elegans) remaining
several weeks in a pond that had become barren of food would stop
growing and develop a growth-ring on the epidermal laminae; he
did not indicate, however, whether these growth-rings differ from
those formed during hibernation.

In species that periodically shed scutes a zone of fracture develops
between the old and new layers of the scute as each new
layer of epidermis is formed, and the old layer is shed. Considering
reptiles as a group, skin shedding is of general occurrence; the
process in Pseudemys and Chrysemys differs in no basic respect
from that in most reptiles. Retention of scutes in terrestrial emyids
and in testudinids is one of many specializations for existence on
land. Retention of scutes protects the shell of terrestrial chelonians
against wear. Some box turtles were observed to have several
scutes of the carapace in the process of exfoliation but no exfoliation
was observed on the plastron. Exfoliation ordinarily occurred
on the scutes of the carapace that were the least worn; the exfoliating
portion included the areola and the three or four oldest
(first formed) layers of the scute. The layer of scute exposed
[Pg 572]
was smooth and had yellow markings that were only slightly less
distinct than those on the portion that was exfoliating.

Wear on the shell of a box turtle reduces the thickness of scutes,
as does the shedding of scutes in the aquatic emyids mentioned.
It is noteworthy that any of the layers in the scute of a box turtle
can form the cornified surface of the scute when the layers above it
wear away or are shed.

It is uncertain whether turtles that have ceased to grow at a
measurable rate continue to elaborate a new layer of epidermis
at the beginning of each season. Greatly worn shells of ornate
box turtles, particularly those of the subspecies luteola, have only
a thin layer of epidermis through which the bones of the shell and
the sutures between the bones are visible. I suspect that, in these
old individuals, the germinal layer of the epidermis does not become
active each year but retains the capacity to elaborate new
epidermis if the shell becomes worn thin enough to expose and
endanger the bone beneath it. The germinal layer of old turtles
loses the capacity to produce color.

Major growth-rings constitute a valuable and accurate history
of growth that can be studied at any time in the life of the turtle
if they have not been obliterated. They are accurate indicators
of age only as long as regular growth continues but may be used
to study early years of growth even in turtles that are no longer
growing. Minor growth-rings, if properly interpreted, provide
additional information on growing conditions in the course of each
growing season.

Nichols (1939a: 16-17) found that the number of growth-rings
formed in marked individuals of T. carolina did not correspond to
the number of growing seasons elapsed; he concluded that growth-rings
were unreliable as indicators of age and that box turtles frequently
skipped seasons of growth. Woodbury and Hardy (1948:166-167)
and Miller (1955:114) came to approximately the same
conclusion concerning Gopherus agassizi. It is significant that these
workers were studying turtles of all sizes and ages, some of which
were past the age of regular, annual growth. Cagle's review of
the literature concerning growth-rings in turtles (1946) suggests
that, in most of the species studied, growth-rings are formed regularly
in individuals that have not attained sexual maturity but are
formed irregularly after puberty.

Cagle's (op. cit.) careful studies of free-living populations of
Pseudemys scripta showed that growth-rings, once formed, did not
change in size, that the area between any two major growth-rings
[Pg 573]
represented one season of growth, and that growth-rings were reliable
indicators of age as long as the impression of the areola
remained on the scutes studied. Cagle noted decreasing distinctness
of growth-rings after each molt.

The relative lengths of the abdominal lamina and the plastron
remain approximately the same throughout life in T. ornata.
Measurements were made of the plastron, carapace, and abdominal
lamina in 103 specimens of T. o. ornata from Kansas and neighboring
states. The series of specimens was divided into five nearly
equal groups according to length of carapace. Table 3 summarizes
the relationship of abdominal length to plastral length, and of
carapace length to plastral length. The mathematical mean of the
ratio, abdominal length/plastral length, in each of the four groups
of larger-sized turtles, was not significantly different from the same
ratio in the hatchling group. The relative lengths of carapace and
plastron are not so constant; the carapace is usually longer than the
plastron in hatchlings and juveniles, but shorter than the plastron
in adults, especially adult females.

[Pg 574]

The length of any growth-ring on the abdominal lamina can be
used to determine the approximate length of the plastron at the
time the growth-ring was formed. Actual and relative increases
in length of the plastron can be determined in a like manner.
For example, a seven-year-old juvenile (KU 3283) with a plastron
74.0 millimeters long had abdominal growth-rings (beginning with
areola and ending with the actual length of the abdominal) 5.9,
7.8, 9.5, 10.7, 12.0, 12.5, 14.3, and 14.9 millimeters long. Using the proportion,

where AB is the abdominal length, PL the
plastral length, AB¹ the length of any given growth-ring, and X
the plastral length at the time growth-ring AB^1 was formed, the
plastral length of this individual was 29.3 millimeters at hatching,
38.8 at the end of the first full season of growth, and 47.2, 53.2,
59.6, 62.1, and 71.0 millimeters at the end of the first, second, third,
fourth, fifth, and sixth seasons of growth, respectively. The present
length of the abdominal (14.9 mm.) indicates an increment of three
millimeters in plastral length in the seventh season, up to the time
the turtle was killed (June 25). This method of studying growth
in turtles was first used by Sergeev (1937) and later more extensively
used by Cagle (1946 and 1948) in his researches on
Pseudemys scripta. Because the plastron is curved, no straight-line
measurement of it or its parts can express true length. Cagle (1946
and 1948) minimized error by expressing plastral length as the
sum of the laminal (or growth-ring) lengths. This method was
not possible in the present study because growth-rings on parts of
one or more laminae (chiefly the gulars and anals) were usually
obliterated by wear, even in young specimens. It was necessary
to express plastral length as the sum of the lengths of forelobe and
hind lobe.

The abdominal lamina was selected for study because of its
length (second longest lamina of plastron), greater symmetry, and
flattened form. Although the abdominal is probably subject to
greater, over-all wear than any other lamina of the shell, wear is
even, not localized as it is on the gulars and anals.

In instances where some of the growth-rings on an abdominal
lamina were worn but other rings remained distinct, reference to
[Pg 575]
other, less worn lamina permitted a correct interpretation of indistinct
rings.

Abdominal laminae were measured at the interlaminal seam;
since the laminae frequently did not meet perfectly along the
midline (and were of unequal length), the right abdominal was
measured in all specimens. Growth-rings on the abdominal laminae
were measured in the manner shown in Plate 22.

Data were obtained for an aggregate of 1272 seasons of growth
in 154 specimens (67 females, 48 males, and 39 of undetermined
sex, chiefly juveniles). Averages of calculated plastral length were
computed in each year of growth for specimens of known sex
(Figs. 9 and 10) and again for all specimens examined. Annual
increment in plastral length was expressed as a percentage of plastral
length at the end of the previous growing season (Fig. 11).
Increment in plastral length for the first season of growth was
expressed as a percentage of original plastral length because of
variability of growth in the season of hatching; growth increments
in the season following hatching are, therefore, not so great as
indicated in Figure 11.

Areas of new laminal growth were discernible on laboratory
hatchlings soon after they ate regularly. Hatchlings that refused
to eat or that were experimentally starved did not grow. The first
zone of epidermis was separated from the areola by an indistinct
growth-ring (resembling a minor growth-ring) in most hatchlings,
but in a few specimens the new epidermis appeared to be a continuation
of the areola. Major growth-rings never formed before
the onset of the first hibernation.

Growth in the season of hatching seems to depend on early
hatching and early emergence from the nest. Under favorable
conditions hatchlings would be able to feed and grow eight weeks
or more before hibernation. Hatchlings that emerge in late autumn
or that remain in the nest until spring are probably unable to find
enough food to sustain growth.

Sixty-four (42 per cent) of the 154 specimens examined showed
measurable growth in the season of hatching. The amount of increment
was determined in 36 specimens having a first growth-ring
and an areola that could be measured accurately. The average
increment of plastral length was 17.5 per cent (extremes, 1.8-66.0
per cent) of the original plastral length. Ten individuals showed
an increment of more than 20 per cent; the majority of these individuals
(8) were hatched in the years 1947-50, inclusive.

[Pg 576]

Fig. 9. See legend for Fig. 10

[Pg 577]

Fig. 10. The relationship of size
to age in T. o. ornata, based on studies of growth-rings in 115 specimens
of known sex (67 females and 48 males) from eastern Kansas. Size is expressed as
plastral length at the end of each growing season (excluding the year of hatching)
through the twelfth and thirteenth years (for males and females, respectively) of
life. Vertical and horizontal lines represent, respectively, the range and mean.
Open and solid rectangles represent one standard deviation and two standard errors
of the mean, respectively. Age is expressed in years.

Some hatchlings that grow rapidly before the first winter are as
large as one- or two-year-old turtles, or even larger, by the following
summer. Individuals that grew rapidly in the season of hatching
tended also to grow more rapidly than usual in subsequent
seasons; 80 per cent of the individuals that increased in plastral
length by 20 per cent or more in the season of hatching, grew faster
[Pg 578]
than average in the two seasons following hatching. Early hatching
and precocious development presumably confer an advantage
on the individual, since turtles that grow rapidly are able better to
compete with smaller individuals of the same age. Theoretically,
turtles growing more rapidly than usual in the first two or three
years of life, even if they grew subsequently at an average rate,
would attain adult size and sexual maturity one or more years before
other turtles of the same age. A few turtles (chiefly males)
attain adult size (and presumably become sexually mature) by the
end of the fifth full season of growth (Figs. 9
and 10). These individuals,
reaching adult size some three to four years sooner than
the average age, were precocious also in the earlier stages of post-natal
development.

Young box turtles reared in the laboratory grew more slowly
than turtles of comparable ages under natural conditions; this was
especially evident in hatchlings and one-year-old specimens.
Slower growth of captives was caused probably by the unnatural
environment of the laboratory. Captive juveniles showed a steady
increase in weight (average, .52 grams per ten days) as they grew
whereas captive hatchlings tended to lose weight whether they
grew or not.

After the first year growth is variable and size is of little value
as an indicator of age. Although in the turtles sampled variation
in size was great in those of the same age, average size was successively
greater in each year up to the twelfth and thirteenth years
(for males and females, respectively), after which the samples
were too small to consider mathematically.

Increments in plastral length averaged 68.1 per cent in the year
after hatching, 28.6 per cent in the second year and 18.1 per cent
in the third year. From the fourth to the fourteenth year the growth-rate
slowed gradually from 13.3 to about three per cent (Fig. 11).
These averages are based on all the specimens examined (with
no distinction as to sex); they give a general, over-all picture
of growth rate but do not reflect the changes that occur in growth
rate at puberty (as shown in Figs. 9 and 10).

Rate of growth and, ultimately, size are influenced by the attainment
of sexual maturity. Adult females grow larger than adult
males. Males, nevertheless, grow faster than females and become
sexually mature when smaller and younger. Examination of gonads
showed 17 per cent of the males to be mature at plastral
lengths of 90 to 99 millimeters, 76 per cent at 100 to 109 millimeters,
[Pg 579]
and 100 per cent at 110 millimeters, whereas the corresponding
percentages of mature females in the same size groups
were: zero per cent, 47 per cent, and 66 per cent. Of the females,
97 per cent were mature at 120 to 129 millimeters and all were
mature at 130 millimeters (Fig. 13). Because growth slows perceptibly
at sexual maturity, it is possible, by examination of growth-rings,
to estimate the age of puberty in mature specimens.

Fig. 11. Average increment in
plastral length (expressed as a percentage
of plastral length at the end of the previous season of growth)
in the season of hatching (H) and in each of the following 14 years
of life, based on 1073 growth-rings. The number of specimens
examined for each year of growth is shown in parentheses. Records
for males and females are combined.

Attainment of sexual maturity, in the population studied, was
more closely correlated with size than with age. For example,
nearly all males were mature when the plastron was 100 to 110
millimeters long, regardless of the age at which this size was attained.
The smallest mature male had a plastral length of 99 millimeters;
according to the data presented in Figures 9 and 10, therefore,
a few males reach sexual maturity in the fourth year, and
increasingly larger portions of the population become mature in
the fifth, sixth, and seventh years. The majority become mature
in the eighth and ninth years. Likewise, females (smallest mature
specimen, 107 mm.) may be sexually mature at the end of the
sixth year but most of them mature in the tenth and eleventh
years.

[Pg 580]

In growing individuals, narrow zones of new epidermis form
on the laminae in spring. Nearly all the growing individuals collected
in May of 1954 and 1955 had zones of new epidermis on
the shell but those collected in April did not. Activity in the first
week or two after spring emergence is sporadic and regular feeding
may not begin until early May. Once begun, growth is more
or less continuous as long as environmental conditions permit foraging.
The formation of minor growth-rings and adjacent growth-zones
in autumn, provides evidence that growth commonly continues
up to the time of hibernation. The number of growing days
per year varies, of course, with the favorableness of environmental
conditions. The length of time (162 days) given by Fitch (1956b:438)
as the average annual period of activity for T. ornata is a good
estimate of the number of growing days per season.

Zones of epidermis formed in some years are wider or narrower
than the zones bordering them (Pl. 22). Zones notably narrower
or wider than the average, formed in certain years, constituted distinct
landmarks in the growth-histories of nearly all specimens; for
example, turtles of all ages grew faster than average in 1954 and
zones of epidermis formed in this year were always wider than those
formed in 1953 and 1955.

An index to the relative success of growth in each calendar year
was derived. Records of growth for all specimens in each age
group were averaged; the figure obtained was used to represent
"normal" or average growth rate in each year of life (Fig. 12).
The over-all averages for the various age groups were then compared
with records of growth attained by individuals of corresponding
age in each calendar year, growth in a particular year being
expressed as a percentage of the over-all average. The percentages
of average growth for all ages in each calendar year were then
averaged; the mean expressed
the departure from normal rate
of growth for all turtles growing in a particular calendar year. For
example, the over-all average increment in plastral length in the
fifth year of life was 12.1 per cent, the increment in the sixth year
was 10 per cent, and so on (Fig. 11). In 1953, turtles in their
fifth and sixth years increased in plastral length by 11.4 and 9.1
per cent, or grew at 94.2 and 91.0 per cent of the normal rate, respectively.
The percentages of normal growth rate for these age
groups averaged with percentages of the other age groups in 1953
[Pg 581]
revealed that turtles grew at approximately 86 per cent of the normal
rate in 1953.

Growth rates were computed for the twelve-year period, 1943-1954,
because of the concentration of records in these years. Scattered
records also were available for many of the years from 1901-1942.
Records for individuals in the season of hatching and the
first full season of growth were not considered.

Direct correlation exists between growth rate and average
monthly precipitation in the season of growth (April to September)
(Fig. 12). In nine of eleven years, the curve for growth rate followed
the trend of the curve for precipitation; but because other
climatic conditions also influenced growth, the fluctuations in the
two curves were not proportional to one another.

Grasshoppers form an important element in the diet of box turtles.
Smith (1954) traced the relative abundance of grasshoppers
over a period of 100 years in Kansas, and this information is of
significance for comparison with data concerning growth of box
turtles. In general, the growth index was higher when favorable
weather and large populations of grasshoppers occurred in the
same year.

In the following summary, the numbers (1 to 5) used to express
the relative abundance of grasshoppers are from Smith (op. cit.).
Maxima and minima refer to the twelve-year period, 1943-1954.
The growth index for each year (shown as a graph in Fig. 12) appears
in brackets and indicates the percentage of normal growth
attained by all turtles in that year.

1954 [126.3]: Growth was better than average for turtles of all
ages. Grasshopper populations were highest (4+) since 1948.
Continuously warm weather, beginning in the last few days of
March, permitted emergence in the first week of April; thereafter
conditions were more or less continuously favorable for activity
until late October. Although there was less than an inch of
precipitation in September, precipitation in August and October
was approximately twice normal and more or less evenly distributed.
Warm weather in early November permitted an additional
two weeks of activity.

1945 [125.5]: This was the second most favorable year for growth
and the second wettest year. Records of growth are all from young
turtles (one to four years old), all of which grew more than average.
Daily maximum temperatures higher than 60 degrees Fahrenheit
[Pg 582]
on 18 of the last 19 days of March, combined with twice the
normal amount of precipitation in the same period, stimulated
early emergence. August and October were both dry (each with
less than one inch of precipitation) but diurnal temperatures remained
warm through the first week in November and probably
prolonged activity of box turtles at least until then. Grasshoppers
were more abundant (3.7) than normal.

1944 [83.1]: This was the poorest growing year for the period
considered. The lack of a continuously warm, wet period in early
spring probably delayed emergence until the last week in April.
Temperatures remained warm enough for activity until early November,
but dry weather in September and October probably curtailed
activity for inducing long periods of quiescence; most of the
precipitation that occurred in the latter two months fell in a one-week
period beginning in the last few days of September. Grasshopper
populations were higher (4.0) than normal.

1953 [85.6]: This was the second poorest growing year and the
driest year in the period considered. Intermittently cold weather
in spring delayed emergence until the last week in April when
nearly an inch of rain fell.
Temperatures were higher than normal
from June to October. The period from September to the end of
October was dry and the small amount of precipitation that occurred
was concentrated chiefly at the beginning and end of that
period. Temperatures in late October and early November were
lower than normal. Grasshopper populations were low (2.2).

1952 [88.3]: Environmental conditions were poor for growth and
much like the conditions described for 1953. In both years growth
was much less than normal in turtles of all ages except for one
group (adults that were 10 and 11 years old in 1952 and 1953,
respectively) that was slightly below normal in 1952 and slightly
above normal in 1953.

The small number of records for 1955 were not considered in
Figure 12. Warm weather in the last half of March lengthened the
growing season, and environmental conditions, as in 1954, were
more or less favorable throughout the rest of the summer; 1955
probably ranks with 1954 as an exceptionally good year for growth
of box turtles.

Although the number of records available for turtles hatched
in the period from 1950 to 1954 is small, a few records are available
for all these years except 1951. In general, small samples of turtles
[Pg 583]
hatched in these years reflect only the difficulty of collecting
hatchlings and juveniles. In 1951, conditions for incubation and
hatching were poor and the lack of records for that year actually
represents a high rate of prenatal and postnatal mortality. Rainfall
in the nesting season was two to three times normal and temperatures
were below normal. Flooding occurred in low areas of Douglas
County and many eggs may have been destroyed when nests
were inundated. Cold weather probably increased the time of
incubation for surviving eggs so that only a few turtles could hatch
before winter. Flooding and cold, wet weather in the season of
growth and reproduction, affecting primarily eggs and hatchlings,
may act as checks on populations of T. ornata in certain years.

Fig. 12. The relation of growth rate in Terrapene o. ornata (solid line) to precipitation (dotted line) in eastern Kansas. "Normal" rate of growth was determined by averaging records of increase in length of plastron for turtles in each age group. The growth index is expressed as a percentage of normal growth and is the mean departure from normal of all age groups in each calendar year. Precipitation is for the period, April to September (inclusive), at Lawrence, Douglas Co., Kansas. The means for precipitation (4.3) and growth index (100) are indicated by horizontal lines at the right of the graph.

The environmental factors governing activity of terrestrial turtles
seem to differ at least in respect to threshold, from the factors influencing
the activity of aquatic turtles. A single month that was
drier or cooler than normal probably would not noticeably affect
[Pg 584]
growth and activity of aquatic emyids in northeast Kansas, but
might greatly curtail growth of box turtles.

Cagle (1948:202) found that growth of slider turtles (Pseudemys
scripta) in Illinois paralleled the growth of bass and bluegills in
the same lake; in the two years in which the fish grew rapidly, the
turtles did also, owing, he thought to "lessened total population
pressure" and "reduced competition for food." Growth of five-lined
skinks (Eumeces fasciatus) on the Natural History Reservation
paralleled growth of box turtles, probably because at least
some of the same environmental factors influence the growth of
both species. Calculations of departure from normal growth in E.
fasciatus, made by me from Fitch's graph (1954:84, Fig. 13), show
that relative success of growth in the period he considered can be
ranked by year, in descending order, as: 1951, 1949, 1948, 1950,
1952. This corresponds closely to the sequence, 1951, 1948, 1949,
1950, 1952, for T. ornata.

Growth almost stops after the thirteenth year in females and
after the eleventh or twelfth year in males, approximately three
years, on the average, after sexual maturity is attained. The oldest
individuals in which plastral length had increased measurably in
the season of capture were females 14 (2 specimens) and 15 (1)
years old. The age of the oldest growing male was 13 years.

The germinal layer of the epidermis probably remains semiactive
throughout life but functions chiefly as a repair mechanism
in adults that are no longer growing. Growth-rings continue to
form irregularly in some older adults. Growth-rings formed after
the period of regular growth are so closely approximated that they
are unmeasurable and frequently indistinguishable to the unaided
eye. If the continued formation of growth-rings is not accompanied
by wear at the edges of the laminae, the laminae meeting at
an interlaminal seam descend, like steps, into the seam (Pl. 22,
Fig. 2). Interlaminal seams of the plastron deepen with advancing
age in most individuals.

Some individuals that are well past the age of regular growth
show measurable increments in years when conditions are especially
favorable. The three oldest growing females were collected in 1954—an
exceptionally good year for growth. Allowing some latitude
for irregular periods of growth in favorable years subsequent to
the period of regular, more or less steady growth, 15 to 20 years is
a tenable estimate of the total growing period.

[Pg 585]

Practically nothing is known about longevity in T. ornata or in
other species of Terrapene although the several plausible records
of ages of 80 to more than 100 years for T. carolina (Oliver, 1955:295-6)
would indicate that box turtles, as a group, are long-lived.
There is no known way to determine accurately the age of an adult
turtle after it has stopped growing. It was possible occasionally
to determine ages of 20 to 30 years with fair accuracy by counting
all growth-rings (including those crowded into the interabdominal
seam) of specimens having unworn shells. Without the presence
of newly formed epidermis as a landmark, however, it was never
certain how many years had passed since the last ring was formed.

Fig. 13. The relationship of
sexual maturity to size in 164 specimens (94 females and 70 males) of
Terrapene o. ornata, expressed as the percentage of mature individuals
in each of five groups arranged according to plastral length. Sexual maturity
was determined by examination of gonads. Solid bars are for males and open
bars for females. The bar for males in the largest group is based on
assumption since no males in the sample were so long as 130 mm. Males mature
at a smaller size and lesser age (see also Figs. 9 and 10) than females.
Plastral lengths of the smallest sexually mature male and female in the
sample were, respectively, 99 and 107 mm.

Mattox (1936) studied annual rings in the long bones of painted
turtles (Chrysemys picta) and found fewer rings in younger than
in older individuals but, beyond this, reached no important conclusion.
[Pg 586]
In the present study, thin sections were ground from the
humeri and femurs of box turtles of various ages and sizes; the
results of this investigation were negative. Distinct rings were
present in the compact bony tissue but it appeared that, after the
first year or two, the rings were destroyed by encroachment of the
marrow cavity at about the same rate at which they were formed
peripherally.

The only methods that I know of to determine successfully the longevity
of long-lived reptiles would be to keep individuals under
observation for long periods of time or to study populations of
marked individuals. Both methods have the obvious disadvantage
of requiring somewhat more than a human lifetime to carry them
to completion. Restudy, after one or more decades, of the populations
of turtles marked by Fitch and myself may provide valuable
data on the average and maximum age reached by T. ornata.

Ornate box turtles probably live at least twice as long as the
total period of growing years. An estimated longevity of 50 years
would seem to agree with present scant information on age. Considering
environmental hazards, it would be unusual for an individual
to survive as long as 100 years in the wild.

Weights of ornate box turtles varied so much that no attempt
was made to correlate weight with size. Absolute weights have
little significance since weight is affected to a large extent by the
amount of fluid in the body. Turtles that had recently imbibed
were naturally heavier than those that had not; turtles brought to
the laboratory and kept there for several days lost weight by evaporation
and by voiding water. Weights of 22 adult females (53
records) and 10 adult males (22 records) averaged 391 and 353
grams respectively, in the period from September, 1954, to October,
1956. Females characteristically gained weight in spring and
early summer and were lighter after nesting. Turtles of both sexes
gained weight in September and October.

At the time of hatching, fontanelles remain where bones of the
shell have not yet articulated with their neighbors. In general, the
fontanelles of the shell are closed by the time sexual maturity is
attained, but some remain open a year or two longer.

The fontanelles of the shell are classified as follows (see Figs.
14 to 16 and 18 to 19):

[Pg 587]

1.) Anteromedian. Rhomboidal; limited anteriorly by hyoplastral
bones and posteriorly by hypoplastral bones; posterior tip of entoplastral
bone may project into this fontanelle.

2.) Posteromedian. Limited anteriorly by hypoplastral bones and
posteriorly by xiphyplastral bones (since hypoplastral bones do
not articulate medially in hatchlings, anteromedian and posteromedian
fontanelles form a single, more or less dumbbell-shaped
opening).

Fig. 14. Extent of closure of
the costoperipheral fontanelles in relation to length of plastron in 17
skeletons of T. o. ornata from eastern Kansas. Extent of closure is
expressed as an estimated percentage of total closure of all the costoperipheral
fontanelles, even though some of them close sooner than others. Closure is
usually complete by the time sexual maturity is attained.

1.) Costoperipheral. Openings between the free ends of developing
ribs, between nuchal bone and first rib, and, between pygal
bone and last rib; limited laterally by peripheral bones; variable
in shape.

2.) Costoneural. Triangular openings on either side of middorsal
line between proximal ends of costal plates and developing neural
plates.

The costoneural fontanelles are nearly closed in individuals
[Pg 588]
of the 70 millimeter (plastron length) class and seldom remain
open after a length of 80 millimeters is attained (Fig. 14). Of
the costoperipheral fontanelles, the anterior one (between first
rib and nuchal bone) closes first and the posterior one (between
last rib and pygal bone) last. It remains open in some turtles in
which the plastron is longer than 100 millimeters. The remaining
costoperipheral fontanelles close in varying sequence but those
in the area of the bridge (nos. 2 to 5), where there is presumably
greater stress on the shell, close sooner than the others.

The plastral fontanelles are closed in most specimens of the
90 millimeter (plastron length) class; the anteromedian fontanelle
closes first.

The meager covering of the fontanelles makes juvenal turtles
more susceptible than adults to many kinds of injuries and to
predation.

Parts of the shell that are more or less movable upon one another
and that function in closing the shell are found in several families
of Recent turtles. African side-necked terrapins of the genus
Pelusios have a movable forelobe on the plastron. Kinosternids
have one or two flexible transverse hinges on the plastron. In the
Testudinidae the African Kinixys has a movable hinge on the
posterior part of the carapace and Pyxis arachnoides of Madagascar
has a short, hinged, anterior plastral lobe. Certain trionychid
turtles, such as Lissemys, utilize the flexible flaps of the carapace
(the flaps of some species are reinforced with peripheral bones)
to close the shell.

Movable shell-parts of turtles are, in general, protective in function;
they cover parts of the soft anatomy that would otherwise
be exposed.

A hinged plastron, capable of wholly or partly closing the shell,
occurs in six genera of the family Emyidae (see introduction).
In these emyids the plastron is divided into two lobes, which are
joined to each other by ligamentous tissue at the junction of the
hyoplastral and hypoplastral bones; externally, the hinge occurs
along the seam between the pectoral and abdominal laminae. This
junction forms a more or less freely movable hinge in adults. The
plastron is attached to the carapace by ligamentous tissue. Both
lobes of the plastron or only the buttresses of the hind lobe may
articulate with the carapace. The former condition obtains in
Emys and Emydoidea; the latter more specialized condition is
found in Terrapene.

[Pg 589]

Fig. 15. Lateral view of adult
shell (× ¾), showing movable parts with anterior portion at
left. (Abbreviations are as follows: ab, axillary buttress; hp, hypoplastron;
hy, hyoplastron; ib, inguinal buttress; p5, fifth peripheral bone; th, transverse hinge).

Fig. 16. Medial view of adult
shell (× ¾), showing movable parts with anterior portion at
left. (Abbreviations as in fig. 15).

Fig. 17. Lateral view of adult shell
(× ¾), showing scutellation of movable parts with anterior
portion at left. (Abbreviations are as follows: ap,
apical scale; ax, axillary scale;
m5, fifth marginal scale; pl, pectoral lamina.)

In generalized emyid turtles such as Clemmys there are no movable
shell parts. The plastron is joined to the carapace by the sutures
of the bridge. A long stout process, the axillary buttress,
arises on each side from the hyoplastron and articulates with the
tip of the first costal. A similar process, the inguinal buttress, arises
from the anterior part of each of the hypoplastral elements and
meets the sixth costal on each side. The buttresses form the anterior
and posterior margins of the bridge. It is clear that movement
of the plastron in many emyids is mechanically impossible
because of the bracing effect of the buttresses.

In Terrapene the movable articulations of the shell are neither
structurally nor functionally developed in juveniles. Adults of T.
ornata have highly modified bony buttresses on the plastron that
are homologous with those in more generalized emyids. The inguinal
buttresses are low and wide, and have a sheer lateral surface
forming a sliding articulation with the fifth and sixth peripheral
bones of the carapace. The axillary buttresses are reduced
to mere bony points near the posterolateral corners of the forelobe
and do not articulate directly with the carapace
(Figs. 15 and 16).

The fifth peripheral bone, constituting the lowest point of the
carapace, has a medial projection that acts as a pivoting point for
both lobes of the plastron; the roughened anterior corners of the
hind lobe articulate with these processes. The roughened posterior
corners of the forelobe of the plastron likewise articulate with these
processes. The posterior process or "tail" of the entoplastron extends
to, or nearly to, the bony transverse hinge.

In juveniles that have been cleared and stained, the homologues
of the parts that are movable in adults are easily identifiable; the
proportions of these parts and their relations to one another are,
however, much different.

In juveniles (Figs. 18 and 19)
the buttresses are relatively longer
and narrower, and are distinct—more nearly like those of generalized
emyids than those of adult T. ornata. The buttresses enclose
a large open space, which in adults is filled by the fifth peripheral.
The hyoplastral and hypoplastral bones are in contact only laterally.
They are firmly joined by bony processes; the interdigitating
nature of this articulation contrasts with its homologue in the adult,
the point where the roughened corners of the forelobes and hind
lobes meet. The fifth peripheral in juveniles (Fig. 19) lies dorsal
to this articulation. The position of the future transverse hinge
corresponds to a line passing through the articulations of the hyoplastra
[Pg 590]
and hypoplastra. The tail of the entoplastron ordinarily
extends posterior to this line in juveniles.

The external scutellation of the plastral hinge in adults also differs
from that in juveniles. In adults (Fig. 17 and
Pl. 22) the transverse
hinge is marked by ligamentous tissue between the pectoral
and abdominal laminae; the forelobe of the plastron is distinctly
narrower than the hind lobe. Two small scales lie near the corner
of the hinge on each side. The larger and more anterior of these
scales is the axillary; it is present in box turtles of all ages. The
smaller scale (Fig. 17), to my knowledge, has never been named
or mentioned in the literature; it is herein termed the apical scale.
It is a constant feature in adults but is always lacking in hatchlings
and small juveniles. Other scales, much smaller than the axillary
[Pg 591]
and apical, occur on the ligamentous tissue of the hinge of some
adults.

Fig. 18. Plastron of hatchling (× 2), cleared and stained to show bony structure. (Abbreviations not listed in legend for Fig. 15 are as follows: af, anteromedian fontanelle; ep, epiplastron; pf, posteromedian fontanelle.)
Fig. 19. Carapace of hatchling (× 1½), cleared and stained to show bony structure; lateral view; anterior end at left. (Abbreviations as in Fig. 15.)		Fig. 20. Lateral view of hatchling (× 1); note the lateral process of the pectoral lamina (pl) extending posterior to the axillary scale (ax) in a position corresponding to the apical scale of adults. There is no external indication of the transverse hinge in young individuals. The yolk sac of this individual has been retracted but the umbilicus (umb) has not yet closed.

In juveniles (Fig. 20) the pectoroabdominal seam contains no
ligamentous tissue and is like the other interlaminal seams of the
plastron. A lateral apex of the pectoral lamina projects upward
behind the axillary scale on each side, in the position occupied by
the apical scale of adults. Examination of a large series of specimens
revealed that the apical scale of adults becomes separated
from the lateral apex of the pectoral lamina at approximately the
time when the hinge becomes functional as such.

Ontogenetic changes in the shell can be summarized as follows:
[Pg 592]
1) Buttresses become less distinct in the first two years of life
(plastral lengths of 40 to 55 mm.); 2) Interdigitating processes of
the forelobes and hind lobes become relatively shorter and wider,
the entoplastron no longer projects posterior to the hinge, the lateral
apex of the pectoral lamina becomes creased, and some movement
of the plastron can take place between the second and third
years (plastral lengths of 55 to 65 mm.); 3) Plastral lobes become
freely movable upon one another and upon the carapace by the end
of the fourth year (plastral length approximately 70 mm.) in most
individuals.

The plastron of a juvenal box turtle is not completely immovable.
The bones of the shell are flexible for a time after hatching and
allow some movement of the plastron; but the relatively greater
bulk of the body in young box turtles would prevent complete closure
of the shell even if a functional hinge were present. Hatchlings
can withdraw the head and forelegs only to a line running between
the anterior edges of the shell. To do so the rear half of the
shell is opened and the hind legs are extended. When the head
and forelegs are retracted to the maximum, the elbow-joints are
pressed against the tympanic region or behind the head; the fore-limbs
cannot be drawn part way across the snout, as in adults.
Hatchlings can elevate the plastron to an angle of approximately
nine degrees; the plastron of an adult, with shell closed, is elevated
about 50 degrees. Hatchlings flex the plastron chiefly in the
region of the humeropectoral seam, rather than at the anlage of
the transverse hinge.

Adult box turtles, when walking, characteristically carry the
forelobe of the plastron slightly flexed. This flexion of the plastron,
combined with its naturally up-turned anterior edge, cause it to
function in the manner of a sled runner when the turtle is moving
forward. A movable plastron, therefore, in addition to its primarily
protective function, seems to aid the turtle in traveling
through tall grass or over uneven ground. The gular scutes, on
the anterior edge of the forelobe, become worn long before other
plastral laminae do.

An adult female from Richland County, Illinois, had an abnormal
but functional hinge on the humeropectoral seam in addition to a
normal hinge on the pectoroabdominal seam. The abnormal hinge
resulted from a transverse break in which ligamentous tissue later
developed. The muscles closing the plastron moved the more
anterior of the two hinges; the normal hinge was not functional.

[Pg 593]

The markings of the shell change first when postnatal growth
begins and again when sexual maturity is attained. They are
modified gradually thereafter as the shell becomes worn.

In hatchlings the ground color ordinarily is dark brown but in
some individuals is paler brown or tan. Markings on the dark
background are pale yellow. Markings on the central and lateral
scutes vary from a regularly arranged series of well defined spots
and a middorsal stripe to a general scattering of small flecks. In
some specimens the pale markings of the carapace are faint or
wanting. Lateral parts of marginal scutes are always pale yellow
and form a border around the carapace.

Close examination of the carapace of any hatchling shows the
following basic arrangement of markings: each lateral scute has
a centrally placed pale spot and four to seven smaller pale marks
arranged around the edge of the scute; each central scute has a
central, longitudinal mark and several (usually two, four, or six)
smaller pale marks arranged around the edge of the scute, chiefly
the lateral edges (Pl. 23). Variations in pattern result when some
or all of the markings divide into two or more parts.

By the end of the first full season of growth, the markings have
a radial pattern. At this stage, the markings of the areola, with the
exception of the central spot, are obscure. The radial marks,
sharply defined and straight-sided, appear only on the newly
formed parts of the epidermal laminae. Each radial mark originates
opposite one of the peripheral marks of the areola. Other
radial marks are developed later by bifurcation of the original
radiations.

The ground color of the plastron of hatchlings is cream-yellow,
or less often, bright yellow. The solid, dark brown markings on the
medial part of each lamina form a central dark area that contrasts
sharply with the pale background (Pl. 24). The soft tissue of the
navel is pale yellow or cream; when the navel closes, the dark central
mark of the plastron is unbroken except for thin, pale lines
along the interlaminal seams.

When growth begins, the areas of newly formed epidermal tissue
on the anterior and medial borders of each areolar scute are pale.
Wide, dark radial marks, usually three per scute, appear on the
newly formed tissue. Subsequently, finer dark radiations appear
between the three original radiations. The wide radiations later
bifurcate. By the time adult or subadult size is reached, the plastron
[Pg 594]
appears to have a pattern of pale radiations on a dark background.
In general, the markings of the plastron are less sharply
defined than the markings of the carapace (Pl. 24).

There is a tendency for the dark markings of the plastron to
encroach on the lighter markings, if no wear on the shell occurs.
However, as the plastron becomes worn, the pale areas become
more extensive and the dark markings become broken and rounded.
Severely worn plastra of some old individuals lack dark markings.
Wear on the carapace produces the same general effect; but markings
of the carapace, although they may become blotched, are never
obliterated in Terrapene o. ornata.

The top of the head in most hatchlings is dark brown, approximately
the same shade as the ground color of the carapace; the
part anterior to the eyes is usually unmarked but a few individuals
have a semicircle of small pale spots over each eye or similar spots
on much of the head. The posterior part of the head is ordinarily
flecked with yellow. The skin on the top of the head, particularly
between the eyes, is roughened. The granular skin of the neck is
grayish brown to cream-yellow. There are one or two large pale
spots behind the eye and another pale spot at the corner of the
mouth. Smaller, irregularly arranged pale markings on the necks
of some specimens form, with the post-orbital and post-rictal spots,
one or two short, ragged stripes. The gular region is pale.

In juveniles, the yellow markings of the head and neck are larger
and contrast more sharply with the dark ground color than in hatchlings.
Markings above the eyes, if present, fuse to form two pale,
semicircular stripes. In some older juveniles yellow marks on top
of the head blend with the dark background to produce an amber
color. The top of the neck darkens or develops blotches of darker
color that produce a mottled effect. Spots and stripes on the side
of the neck remain well defined. The skin on top of the head becomes
smooth and shiny.

Adult females tend to retain the color and pattern of juveniles
on the head and neck although slight general darkening occurs
with age. Many adult females have the top of the head marked
with bright yellow spots. In adult males, the top and sides of the
head, anterior to the tympanum, are uniformly grayish green or
bluish green; the mandibular and maxillary beaks are brighter,
yellowish green. Markings on the head and neck of most adult
males are obscure (Pl. 25) but the sides of the neck remain mottled
in some individuals.

The antebrachium has large imbricated scales and is distinctly
[Pg 595]
set off from the proximal part of the foreleg which is covered with
granular skin. The antebrachial scales of hatchlings are pale yellow;
each scale is bordered with darker color. General darkening
of the antebrachium occurs at puberty. In adult females each scale
on the anterior surface of the antebrachium is dark brown and has
a contrasting yellow, amber, or pale orange center. The anterior
antebrachial scales of adult males are dark brown to nearly black
and have bright orange or red centers. Old males have thickened
antebrachial scales.

The iris of hatchlings and juveniles is flecked with yellow and
brown; the blending of these colors makes the eye appear yellow,
golden, or light brown when viewed without magnification. Adult
females retain the juvenal coloration of the eye; the iris of adult
males is bright orange or red. The work of Evans (1952) on T.
carolina suggests that eye color in box turtles is under hormonal
control.

Presence or absence of areolae on laminae of the shell indicated
degree and sequence of wear. The anterior edges of carapace
and plastron, and the slightly elevated middorsal line (Pl. 23) wear
smooth in some individuals before the first period of hibernation.
Subsequent wear on the carapace proceeds posteriorly. For example,
turtles that retained the areola of the third central lamina,
retained also the areolae of the fourth and fifth centrals; when
only one central areola remained, it was the fifth. Lateral laminae
wear in the same general sequence. The areola of the fifth central
lamina, because of its protected position, persists in adult turtles
that are well past the age of regular growth. Areolae that are retained
in some older turtles are shed along with the epidermal
layers formed in the first year or two of life. Wear on the shell is
probably correlated with the habits of the individual turtle;
smoothly-worn specimens varied in size and age but were usually
larger, older individuals. No smoothly worn individual was still
growing.

Wear on the plastron is more evenly distributed than wear on
the carapace; wear is greatest on the lowest points of the plastron
(the gular laminae, the anterior portions of the anal laminae, and
the lateral edge of the tranverse hinge).

The claws and the horny covering of the jaws are subject to
greater wear than any other part of the epidermis; presumably
they continue to grow throughout life. The occasional examples
of hypertrophied beaks and claws that were observed, chiefly in
[Pg 596]
juveniles, were thought to result from a continuous diet of soft
food or prolonged activity on a soft substrate. Ditmars (1934:44,
Fig. 41) illustrated a specimen of T. carolina, with hypertrophied
maxillary beak and abnormally elongate claws, that had been kept
in a house for 27 years.

The conformation of the maxillary beak in all species of Terrapene
is influenced to a large extent by wear and is of limited value
as a taxonomic character. The beak of T. ornata is slightly notched
in most individuals at the time of hatching and remains so throughout
life. The underlying premaxillary bone is always notched or
bicuspidate. The sides of the beak are more heavily developed
than the relatively thin central part. Normal wear on the beak
maintains the notch (or deepens it) in the form of an inverted
U or V, much in the manner of the bicrenate cutting edge on the
grooved incisors of certain rodents. In a series of 34 specimens of
T. ornata from Kansas, selected at random from the K. U. collections,
92 per cent had beaks that were "notched" to varying
degrees, four per cent had hooked (unnotched) beaks, and four
per cent had beaks that were flat at the tip (neither hooked nor notched).

Fig. 21. Plantar views of right
hind foot (male at left,
female at right) of T. o. ornata (× 1), showing sexual
dimorphism in the shape and position of the first toe.
The widened, thickened, and inturned terminal phalanx
on the first toe of the male is used to grasp the female
before and during coitus.

Differences between adult males and females of T. ornata have
been mentioned in several places in the preceding discussion of
growth and development. Several sexual characteristics—greater
[Pg 597]
preanal length, thickened base of the tail, slightly concave plastron,
and smaller bulk—are found also in males of many other kinds
of emyid turtles. From females, males of T. ornata are most easily
distinguished by the bright colors of their eyes, heads, and antebrachial
scales. An additional, distinctive characteristic of males
is the highly modified hind foot. The first toe is greatly thickened
and widened; when the foot is extended, the first toe is held in
a horizontal plane nearly at right angles to the medial edge of the
plantar surface (Fig. 21). The hind foot of females is unmodified
in this respect. Males tend to have heavier, more muscular hind
legs than females.

The bright colors of males are maintained throughout the year
and do not become more intense in the breeding season. Males
of T. o. luteola become melanistic in old age whereas males of the
subspecies ornata do not. In old males of luteola the skin becomes
dark gray, bluish, or nearly black and much of the bright
orange or red of the antebrachial scales and the green of the head
is obliterated; the iris may also darken but in most specimens it
retains some red. Females of luteola tend also to darken somewhat
in old age but not so much as males; females of ornata do
not. Table 4 summarizes the more important secondary sexual
characters of T. ornata.

[Pg 598]

Tolerances to environmental temperatures, and reactions to
thermal stimuli influence the behavior of ectothermal animals to a
large extent. Terrapene ornata, like other terrestrial reptiles inhabitating
open grassland, is especially subject to the vicissitudes
of environmental temperature. Other species of turtles living in
the same area are more nearly aquatic and therefore live in a microhabitat
that is more stable as regards temperature.

Approximately 500 temperature readings in the field and many
others in the laboratory were obtained from enough individuals to
permit interpretation of reactions involved in basking, in seeking
cover, and in emerging from temporary periods of quiescence at
various times of the day.

Box turtles commonly used open places such as cow paths,
ravines, and wallows, for basking as well as for feeding and as routes
of travel. Burrows, dens beneath rocks, and forms, were used as
shelter from high and low temperatures as well as from predators.
Determining whether a turtle was truly active (moving about freely,
feeding, or copulating), was basking, or was seeking shelter was
difficult because the turtle sometimes reacted to the observer; for
instance, basking turtles, whose body temperatures were still suboptimum,
might take cover when surprised, and truly active turtles
might remain motionless and appear to be basking. By scanning
open areas from a distance with binoculars, an observer frequently
could determine what turtles were doing without disturbing them.
In the final analysis of data, temperature records accompanied by
data insufficient to determine correctly the state of activity of the
turtle, were discarded, as were temperature records of injured
turtles and turtles in livetraps.

Cowles and Bogert (1944:275-276) and Woodbury and Hardy
(1948:177) emphasized the influence of soil temperatures on body
temperatures. It is thought that air temperatures played a more
important role than soil temperatures in influencing body tempera
[Pg 599]tures
of T. ornata. Soil temperatures were taken in the present
study only when the turtle was in a form, hibernaculum, or den.

Cowles and Bogert (1944:277) determined optimum levels of
body temperature of desert reptiles by averaging body temperatures
falling within the range of normal activity; they defined this range
as, "… extending from the resumption of ordinary routine
[activity] … to … a point just below the level at
which high temperatures drive the animal to shelter." Fitch
(1956b:439) considered optimum body temperature in the several
species that he studied to be near the temperature recorded most
frequently for "active" individuals; he found (loc. cit.) that of body
temperatures of 55 active T. ornata, 66 per cent were between 24
and 30 degrees, and that the temperatures 27 and 28 occurred most
frequently. Fitch concluded (op. cit.:473) that the probable optimum
body temperature of T. ornata was 28 degrees and that
temperatures from 24 to 30 degrees were preferred. Although Fitch
treated all non-torpid individuals that were abroad in daytime as
"active" and did not consider the phenomenon of basking, his
observations on optimum body temperature agree closely with my
own.

Body temperatures of 153 box turtles that were known definitely
to be active, ranged from 15.3 to 35.3 degrees. The mean body
temperature for active turtles was 28.8 degrees (± 3.78σ)
(Fig. 22).
Ninety-two per cent of the temperatures were between 24 and 30
degrees and 50 per cent were between 28 and 32; temperatures of
29 and 30 degrees occurred most frequently (22 and 21 times,
respectively). The ten body temperatures below 24 degrees all
were recorded before 9 A. M. on overcast days when the air was
cool and humid. It is noteworthy that two of these low temperatures
(18.8° and 19.0°) were from a copulating pair of turtles; two
others (21.8° and 22.0°) were from individuals that were eating.
The highest temperature (35.3°) was from a large female that was
feeding at mid-morning in a partly shaded area.

The mean body temperature for active individuals (Fig. 22)
is probably somewhat below the ecological optimum, because a
few temperatures were abnormally low. The large number of
body temperatures in the range of 29 to 31 degrees indicates an
optimum closer to 30 degrees. Optimum body temperatures may
vary somewhat with the size, sex, or individual preference of the
turtle concerned.

[Pg 600]

Although basking is common in terrestrial turtles, only a few
authors have mentioned it. Woodbury and Hardy (1948:177-178)
did not use the term in their account of thermal relationships in
Gopherus agassizi; their discussion indicates, however, that the
tortoises move alternately from sunny to shady areas to regulate
body temperature. Desert tortoises removed from hibernacula and
placed in the sun warmed to approximately 29.5 degrees before
they became active, although a few did so at temperatures as low
as 15 degrees. According to Cagle (1950:45), Sergeev (1939)
studied body temperature and activity in the Asiatic tortoise,
Testudo horsefieldi, and found that individuals basked for as
much as two hours in the morning before beginning the first activity
of the day (feeding), but that tortoises did not bask after a
period of quiescense from late morning to late afternoon, during
which body temperatures were seemingly maintained nearer the
optimum than they were during nocturnal rest; body temperatures
rose to approximately 30 degrees before the tortoises became active.
Since body temperatures of 23 to 24 degrees were maintained
at night, the basking range of Testudo horsefieldi may be
considered to be approximately 23 to 32 degrees.

Ornate box turtles basked chiefly between sunrise and 10 or
11 A. M. Body temperatures of 60 basking turtles ranged from
17.3 to 31.4 degrees (mean, 25.5 ± 3.08σ). More than two-thirds
(42) of these body temperatures were higher than the air temperature
near the turtle, indicating probably that body temperature
rises rapidly once basking is begun. In the instances where body
temperature was below air temperature, the turtles had recently
begun to bask (many were known to have just emerged from forms
or other cover where they had spent the night) or were warming
up more slowly because of reduced sunlight. On cloudy days basking
began later than on clear days and body temperatures usually
remained at a suboptimum level. Turtles that basked on days
that were cloudy and windy, or cold and windy, did so in sheltered
places, usually on the leeward sides of windbreaks such as limestone
rocks, rock fences, or ravine banks. It was evident in these
instances that the turtles either sought such shelter from the wind
or remained ensconced in the more complete shelter of a form
or burrow, not emerging at all.

Open areas of various kinds were used as basking sites. Level
ground—such as on roads, cattle pathways, and bare areas surrounding
[Pg 601]
farm ponds—having unobstructed morning sunlight,
nearby dense vegetation, and choice opportunities for feeding
(cow dung, mulberry
trees) was preferred. Basking was frequently
combined with feeding; in several instances box turtles
were noted early in the morning at suboptimum body temperatures
eating grasshoppers, berries, or dung insects. The predilection of
box turtles for open areas is probably important in permitting extended
activity at suboptimum temperatures. T. ornata probably
carries on more nearly normal activity on cool days than do reptilian
species with more sharply delimited thermal tolerances. Collared
lizards (Crotaphytus collaris), for example, are chiefly inactive on
days when the sky is overcast, although a few individuals having
suboptimum body temperatures can be found in open situations
(Fitch, 1956a:229 and 1956b:442).

Fig. 22. The relationship of
body temperature (Centigrade) and kind of activity in T. o. ornata,
compiled from 355 field observations. Vertical and horizontal lines represent,
respectively, the range and mean. Open and solid rectangles represent one
standard deviation and two standard errors of the mean, respectively.

The foregoing remarks on basking indicate the approximate,
normal, thermal tolerances of ornate box turtles. Many additional
records of body temperature were taken from turtles that were
found under cover. Turtles under cover in daylight were usually
[Pg 602]
seeking protection from either below-optimum or above-optimum
temperatures. In avoiding low temperatures, turtles usually chose
more complete and permanent cover than in avoiding high temperatures.

Body temperatures of 64 box turtles that were seeking cover or
that were under cover because of high temperatures ranged from
28.9 to 35.8 degrees (mean, 31.9 ± 1.55σ). Fifty-nine of these temperatures
(92 per cent) were 30 degrees or higher. Figure 22
shows this range to overlap broadly with the temperature range of
active turtles and the means of the two groups are close to each
other. Body temperatures below 30 degrees (5) were all recorded
late in the morning on hot summer days when the air temperature
was well above 30 degrees; they are somewhat misleading because
they are from turtles that were under cover long enough to lower
body temperature to the range of activity although the turtles remained
under cover because of hazardous environmental temperatures.

The commonest retreats used by box turtles to escape heat were
burrows of other animals and small dens under thick limestone
rocks, where the air remained cool, even in late afternoon. Most
of the burrows and dens on the Damm Farm were known to me
and could be checked each day. Turtles seeking temporary refuge
from high temperatures characteristically rested just inside the
opening of a den or burrow. Less frequently, turtles burrowed into
ravine banks or just under the sod on level ground. A number of
individuals with above-optimum body temperatures were found in
the shade of trees or high weeds in early afternoon on hot days.
Mulberry trees provided ample shade for such activity and, in
June and July, when ripe mulberries were abundant on the ground,
turtles frequently fed on them at times of the day when temperatures
were more hazardous in other areas.

Several turtles were found buried in mud or immersed in water
at the edges of ponds in the hottest part of the day; they were discovered
at first by accident and, on subsequent field trips by systematic
probing. Ordinarily the turtles were covered with mud or
muddy water and remained motionless, except for periodically
raising the head to the surface to breath. There was little vegetation
near the edges of ponds and by late morning on hot days the
temperature of the shallowest water was as high as the air temperature
or higher. Correspondingly, turtles found resting in mud and
water had body temperatures much higher than turtles in dens,
burrows, or forms at the same time of day. Box turtles that retreat
[Pg 603]
to mud or shallow water cool themselves less efficiently than they
would in drier, better protected microhabitats. I found no evidence
that turtles went into deeper water to cool themselves.

The length of time spent under cover varied; most turtles had
two daily periods of activity, the second beginning in late afternoon.
Some turtles moved from shelter to shelter in the time between
periods of activity. Several turtles were known to remain quiescent
continuously for several days in the hottest part of the summer.

The maximum temperature that a reptile can tolerate physiologically
is ordinarily higher than the maximum temperature tolerated
voluntarily (Cowles and Bogert, 1944:277); but, the two
maxima may be separated by only a few degrees. Most poikilothormous
vertebrates neither tolerate nor long survive body temperatures
exceeding 40 degrees (Cowles and Bogert, op. cit.:269).

It is evident (Fig. 22) that ornate box turtles do not often tolerate
body temperatures above 33 degrees and that temperatures in
excess of 35 degrees are probably never tolerated under natural
conditions. At 9:15 A. M. on July 5, 1955, an adult female emerged
from mud where she had spent the night (body temperature 28.4°,
mud 28.4°, air 30°). After foraging for 40 minutes in bright sunlight
on a grassy hillside she had moved approximately 100 feet
and her temperature had reached 34.6 degrees (air 33.0°). At
9:56 A. M. she moved rapidly and directly to a den under a rock
nearby; 15 minutes later her body temperature had not changed
but after 65 minutes it had dropped to 33.4 degrees. The temperature
of air in the den was 31 degrees. This female began her activities
at nearly optimum body temperature relatively late in the
morning and, by foraging intensively for less than one hour, probably
was able nearly to satisfy her daily food requirements; by foraging
near suitable cover she could remain active until her body
temperature reached a critical threshold, and she thereby saved
time otherwise required for finding cover or making a form.

The following observations, extracted from field notes, indicate
that body temperatures near 40 degrees are the approximate lethal
maximum and are well above those temperatures voluntarily tolerated
by T. ornata. On July 4, 1955, a subadult female was in the
water at the edge of a pond. The temperatures of the air, water,
and turtle were 32.0, 30.6, and
30.2 degrees, respectively. At 11
A. M. the turtle was tethered in direct sunlight on the hard-baked
clay of the pond embankment (temperature of air 33.4°). The
turtle's response to steadily rising body temperature over a period
of 31 minutes is illustrated by the following notes.

[Pg 604]

The overheating may have incapacitated the turtle since it
moved only 50 feet in the next two days; its body temperatures
on the two days subsequent to the experiment were 26.8 and
20.6, respectively.

The mentioned gaping, as in higher vertebrates generally, cools
the animal by evaporation from the moist surfaces of the mouth
and pharynx. By keeping the mouth open for more than a few
minutes at a time in hot dry weather, a turtle would surely lose
body water in amounts that could not always be easily replaced.
Ornate box turtles seem to utilize evaporation for cooling only in
emergencies and rely for the most part on radiation and conduction
[Pg 605]
to lower body temperature after reaching a relatively cool, dark retreat.

Box turtles were never active at body temperatures below 15
degrees and were seldom active at temperatures below 24 degrees.
The two lowest temperatures (15.3° and 16.3°) were taken from
individuals crossing roads on overcast days in early May.

In 78 box turtles that were under cover because their environmental
temperatures were low, the body temperatures ranged from
2.7 to 30.6 degrees (mean 19.8 ± 6.38σ). The range of body temperatures
in this group is greater than in the other groups shown in
Figure 22 because low body temperatures were studied over a wide
range of conditions, including hibernation.

Box turtles actually seek cover because of low temperatures only
in fall and spring and on occasional unseasonable days in summer
when temperatures drop rapidly. Retreat to cover, in the normal
cycle of daily activity, is governed usually by high temperatures
at mid-day or by darkness at the end of the day. Turtles in dens,
burrows, and grass forms, tended to burrow if temperatures remained
low for more than a few hours.

Box turtles under cover where they cannot bask have little control
over the lower range of body temperatures. The freezing
temperatures of winter can be escaped by burrowing deeper into
the ground. Temperatures approaching the lethal minimum, however,
seldom occur during the season of normal activity. By remaining
hidden in a burrow or den therefore, box turtles are fairly
well protected from predators but are at a thermal disadvantage.

A number of turtles that had wet mud on their shells were
found basking in early morning near ditches, ponds, and marshy
areas; several others were partly buried in mud, shortly after daybreak,
and another was at the edge of a pond after dark.

Eight adults, located just as they emerged from cover in early
morning on sunny days, had body temperatures of 19.7, 21.9, 24.2,
24.5, 25.8, 26.6, 28.7, and 29.5 degrees. In five emerging from earth
forms, body temperatures were at least a degree or two below the
temperature of the air; the other three came from mud or shallow
water and had body temperatures higher than the air temperature.

Temperature is probably the primary stimulus governing emergence
after temporary periods of quiescence. Turtles in earthen
forms are usually completely covered or are head downward with
only the hind quarters exposed. Obviously, the more thoroughly
[Pg 606]
a turtle protects itself (beneath the insulating cover of a form,
burrow, or den) against unfavorable temperatures, the longer it
will take for favorable temperatures to bring about normal activity
again. Turtles in forms and deep burrows have a minimum
of contact with the outer environment; but in dens beneath rocks
and in shallow burrows light and air can enter freely. Turtles
might be influenced in their activities to some extent by the intensity
of light at the opening of a burrow or den; they are surely
stimulated by changes in the temperature and humidity of air
coming through the opening. Shallow retreats that a turtle can
enter and leave with the least effort therefore seem most efficient
for purposes of thermocontrol, especially when they provide earthen
surfaces into which the turtles can burrow more deeply if more
severe environmental conditions develop.

In October, 1955, nine T. ornata of various sizes, collected in
Douglas County, Kansas, were brought to the laboratory for observation
under conditions of controlled temperature. They were
kept at room temperature for several days and were fed regularly,
with the exception of one hatchling that was fed nothing in this
period. On October 22 the turtles were placed in a room where
the temperature was maintained constantly at zero degrees. One of
the nine turtles, an adult female, was killed with chloroform immediately
prior to its removal to the cold room. A list of the turtles
used in this experiment is given below.

Turtles were kept in the cold room for periods of 100 minutes
(hatchlings and juveniles) and 200 minutes (adults). The entire
experiment, including the time in which the turtles were allowed
to warm after they were taken from the cold room, covered a
period of nearly six hours (375 minutes) during which the turtles
were under constant observation. Individual body temperatures
were taken continuously in this period (39 for each juvenile and
24 for each adult) in the order that the turtles were numbered;
gaps between records of the body temperature of a given individual
[Pg 607]
therefore represent the time required to record temperatures
for the rest of the turtles in the group. The rates of rise and fall
of temperature for each of the nine turtles considered are shown
as a graph in Figure 23. Rate of temperature change was inversely
proportional to bulk; hatchlings, for example, cooled and warmed
a little more than twice as rapidly as did adults. Rate of temperature
change was intermediate in juveniles but was more nearly like
that of adults in the warming phase and closer to that of hatchlings
in the cooling phase (Table 5).

Considering that hatchling no. 2 was smaller than no. 1, the rate
of change in its temperature did not seem to be significantly altered
by starvation. The adult males showed a tendency to change
temperature faster than adult females even though both males were
larger than any of the females. The slight difference in rate of
temperature change between the sexes (Fig. 23) may have been
fortuitous.

One hatchling (No. 1), when its temperature dropped below one
degree, fully extended all four limbs and the body was elevated
and only the anterior edge of the plastron was in contact with the
confining glass dish. Raising the body from an uncomfortably cold
or hot substrate is a well known phenomenon in many lizards and
in crocodilians, but to my knowledge has not been reported for
turtles.

[Pg 608-9]

Click on image to view larger sized.

Fig. 23. Changes in temperature
of the body of four juvenal (nos. 1 to 4) and five adult individuals of T. o. ornata
(nos. 5 to 9) exposed to a constant air temperature of zero degrees Centigrade for periods
of 100 and 200 minutes, respectively. The vertical arrows indicate when the turtles were
removed to an air temperature of 27 degrees. Sizes and weights of the turtles used are
given in the text. Turtle number nine, a female, was killed by means of chloroform before
experiment began. Rate of change in temperature in specimens was inversely proportional
to size. All turtles survived the experiment.

[Pg 610]

Hibernating turtles and those experimentally chilled were usually
comatose but were almost never completely incapacitated even at
temperatures at or near zero degrees. Experimental pinching,
probing, and pulling revealed that muscles operating the neck, the
limbs, and the lobes of the plastron could be controlled by the turtle
at low temperatures; hissing, resulting from rapid expulsion of air
through the mouth and nostrils (when the head and limbs are drawn
in reflexively) occurred at all body temperatures but was sometimes
barely audible in the coldest turtles. Of all living turtles observed,
only two (hatchlings 1 and 2 in coldroom experiment) were completely
immobile at low temperatures, failing to respond even to
pinpricks at body temperatures of 0.8 and 1.7 degrees, respectively,
although other turtles, under the same experimental conditions,
consistently gave at least some response to the same stimulation.

Turtles chilled experimentally continued to move about voluntarily,
albeit sluggishly, at temperatures much lower (2.5° for each
of four adults; 10.0° and 6.2° for two juveniles) than those at which
locomotion was resumed in the warming phase (13° for the adults,
21.7° and 20.1° for the juveniles). Hatchlings chilled so rapidly
that it was difficult to ascertain accurately the temperature at which
inactivity was induced. Juveniles became active gradually, moving
slowly about when the body temperature reached approximately 20
degrees but not attempting more strenuous activities such as
climbing the walls of enclosures, until body temperatures of 22 to
25 degrees were attained. Adults, on the other hand, exhibited
"normal" activity as soon as they became voluntarily active.

The ability of ornate box turtles to move about when the body
temperature is near the lethal minimum probably enables those
caught in the open by a sudden drop in environmental temperature
to find cover that keeps them from freezing to death. Prolonged
chilling, on the other hand, seems to create a physiologically different
situation; the temperature at which activity is resumed is
higher and subject to less variation.

Juveniles were more rapidly affected by environmental temperatures,
were subject to different thresholds, and were inactive over
a wider range than were the adults. Indeed, the rate of chilling,
rather than absolute body temperature alone, might in large measure
influence the reactions of turtles to environmental temperatures.
If this be so, smaller turtles, having a narrower thermal range of
normal activity, must lose at least some of the advantages gained
by their ability to warm up more rapidly.

Hatchlings and juveniles at the Damm Farm were always active
on days when at least some adults were also active. Fitch
(1956b:466) found that, in northeastern Kansas, species of small
reptiles and amphibians are active earlier in the season than larger
[Pg 611]
species and that the young of certain species become active earlier
than adults. Fitch stated, "… small size confers a distinct
advantage in permitting rapid rise in body temperature by contact
with warmed soil, rock or air, until the threshold of activity is attained";
he pointed out also that young animals, if able to emerge
earlier than adults, would benefit from a longer growing season.
Hatchlings and juveniles of T. ornata would benefit greatly from an
extra period of activity of say, one or two weeks in spring and a
similar period in autumn, especially if food were plentiful. The
extra growth realized from such a "bonus" period of feeding would
significantly increase the chance of the individual turtle to survive
in the following season of growth and activity.

Ornate box turtles are active within a narrower range of temperatures
than are aquatic turtles in nearby ponds and streams of the
same region. Observations by William R. Brecheisen and myself
on winter activity of aquatic turtles indicate that, in Anderson
County, Kansas, the commoner species (Chelydra serpentina,
Chrysemys picta, and Pseudemys scripta) are more or less active
throughout the year; although they usually do not eat in winter,
they are able to swim about slowly and in some instances (P.
scripta) even to carry on sexual activity at body temperatures only
one or two degrees above freezing. But, ornate box turtles hibernating
in the ground a few yards away are incapable of purposeful
movement at such low body temperatures.

In northeastern Kansas ornate box turtles are dormant from late
October to mid-April—approximately five and one half months of
the year. Individuals may be intermittently active for short periods
at the beginning and end of the season, however. Once a permanent
hibernaculum is selected dormancy continues until spring;
unseasonably warm weather between mid-November and March
does not stimulate temporary emergence. There is little movement
during dormancy except for the deepening or horizontal extension
of the hibernaculum.

Woodbury and Hardy (1948:171) found desert tortoises (Gopherus
agassizi) in dormancy from mid-October to mid-April in
southwestern Utah; some tortoises became temporarily active on
warm days in winter. Cahn (1937:102) was able to compare hibernation
in several individuals each of T. ornata and T. carolina, kept
under the same conditions in Illinois. Individuals of T. ornata burrowed
into the ground in October, two weeks before those of T. carolina
[Pg 612]
did, and continued to burrow to a maximum depth of 22½
inches. Some individuals of T. carolina spent the entire winter in
the mud bottom of a puddle and became semiactive on warm winter
days. Other individuals of T. carolina burrowed nearly as deeply as
did T. ornata. Individuals of T. ornata emerged from hibernation
one or two weeks later in the spring than did those of T. carolina.
There are some indications that populations of T. carolina in eastern
Kansas are dormant for a shorter period of time than those of T. ornata
but comparative studies are needed to verify this. Richard B.
Loomis gave me a large female of T. carolina that he found active
beside a highway in Johnson County, Kansas, on November 23,
1954; on that date most individuals of T. ornata under my observation
had already begun permanent hibernation but a few at the
Reservation were still semiactive.

Fitch (1956b:438) listed earliest and latest dates on which box
turtles were active at the Reservation in the years 1950 to 1954;
in the five year period box turtles were active an average of 162
days per year (range, 140-187) or approximately 5.3 months of
the year. It is significant that 1954, having the most days of activity
was, according to my studies of growth-rings, an exceptionally
good year for growth. Fitch's data indicate the approximate season
of growth and reproduction but not of total activity, since he
did not take into account the sporadic movements of box turtles in
late fall and early spring.

Activity in autumn is characterized by movement into ravines and
low areas; many turtles move into wooded strips along the edges
of fields or small streams. Sites protected from wind, providing
places for basking and for burrowing, are sought. Burrows of
other animals, along the banks of ravines, were often used for temporary
shelter; overhanging sod at the lips of ravine-banks provided
cover beneath which turtles could easily burrow. After mid-October
progressively fewer box turtles were found in open places and
activity was restricted to a few hours in the warmest part of the
day.

Low air temperature probably is the primary stimulus for hibernation.
Autumn rains are usually followed by a decrease in general
activity. Rain probably hastens burrowing by softening the
ground.

Ornate box turtles more often than not excavate their own hibernacula.
Digging begins with the excavation of a shallow form
which is deepened or extended horizontally over a period of days
or weeks. Such hibernacula are sometimes begun at the edges of
[Pg 613]
rocks or logs; the overhanging edge of an unyielding object acts as
a fulcrum on the shell and hastens digging. Ornate box turtles
are slow but efficient burrowers.

Forms in open grassy areas are begun at an angle of 30 to 40
degrees; an adult box turtle requires approximately one hour to
burrow far enough beneath the sod to conceal itself but can dig into
soft, bare earth much more rapidly. Once a hibernaculum is
begun, all four feet are used for its excavation, the front feet doing
most of the digging and the hind feet pushing loose earth to the
rear.

Several turtles were seen entering burrows and dens in late autumn
and trailing records showed that some individuals visited
several of these shelters in the course of a single day.

By means of systematic probing of known hibernacula it was
found that they are deepened gradually in the course of the winter.
Depth seems to be governed by the temperature of the soil. Hibernacula
in wooded or sheltered areas were ordinarily shallower than
hibernacula in open grassland.

In the autumn of 1953-54 two pens were constructed at the Reservation
in order to study hibernation; one pen was on a wooded
hillside and the other was on open grassland. Turtles in the grassland
pen were in newly excavated hibernacula, just beneath the
sod, on October 25 and did not emerge for the remainder of the
winter, whereas turtles in the woodland pen were intermittently
active until November 10. Correspondingly, turtles in the grassland
pen descended to depths of eight and one half and 11½ inches,
respectively, whereas those in the woodland pen were covered by
a scant six inches of loose earth and leaf litter. In 1954 four turtles
were traced (by means of trailing threads) to hibernacula on
wooded slopes at the Reservation; two entered permanent hibernacula
on November 13 and two remained semiactive until sometime
after November 20. All four turtles spent the winter in hibernacula
that were not more than six inches deep. Temperatures of
the soil at a depth of
nine inches were usually slightly lower at the
grassland pen than at the woodland pen on a given date. It is
probably significant that individuals with trailing devices and individuals
in experimental pens furnish the latest records for autumn
activity. The unnatural conditions created by confining the turtles
in pens restricted the number of hibernation sites that were available
to them; although trailing devices did not affect the normal
movements of box turtles on the surface of the ground these devices
certainly hampered the turtles somewhat in digging. However,
[Pg 614]
it is noteworthy that box turtles are able to move about after
mid-November, whether this is of general occurrence under more
natural conditions or not. Depths of hibernacula at the Damm
Farm were also influenced by amount of vegetation or other cover.
Maximum depth of hibernacula in more or less open situations
ranged from seven to 18 inches whereas a female hibernating in a
ditch that was covered with a thick mat of dead grasses was four
inches beneath the surface of the soil, and another female was only
two and one half inches below the floor of a den.

Several T. ornata kept by William R. Brecheisen in a soil-filled
stock tank on his farm in the winter of 1955-56, burrowed to maximum
depths of seven to eight inches in the course of the winter.
A layer of straw covered the soil. All the turtles were alive the
following spring except for one juvenile, found frozen at a depth of
one inch on December 30 (the lowest air temperature up to this
time was approximately -12°). Three adult and 24 juvenal T.
ornata hibernating in the earth of an outdoor cage at the University
of Kansas in the winter of 1955-56, were all dead on December 3
after air temperatures had reached a low of -12 degrees.

Ornate box turtles are usually solitary when hibernating; in the
rare instances in which more than one turtle is found in the same
hibernaculum, the association has no social significance and is simply
a reflection of the availability and suitability of the hibernaculum.
The only communal hibernaculum—the "Tree Den"—at the
Damm Farm was discovered on October 16, 1955, after a turtle was
traced to it by means of a trailing thread. The flask-shaped cavity,
approximately two and one-half feet deep, in the north-facing bank
of a narrow ravine, had an entrance one foot wide and nine inches
high, nearly flush with the bottom of the ravine. Grasses on the
bank of the ravine hung over the entrance and nearly concealed it.
The steep sides of the ravine protected the entrance from wind.

Seven turtles were in the den when it was discovered, and on
each of five subsequent visits from October 20, 1955, to March 6,
1956, fewer turtles were found in the den. Figure 24 shows the
approximate length of stay of each known occupant of the den.
Only one of the turtles (an adult female) that left the den returned.
Turtles found in the den on three visits in October were more or
less torpid and were seen easily from the entrance but on November
6 the two remaining individuals had burrowed into the sides
and floor of the den.

Three turtles (one female, one male, and one juvenile) were
found in separate form-hibernacula within a few inches of one
[Pg 615]
another on November 6, 1955 (Pl. 21, Fig. 2). The common entrance
to all three hibernacula was a shallow depression that resulted
from an old post-hole. Soil in the depression was loose and moist
and ideal for burrowing. The three hibernating turtles were situated,
in a vertical plane, at depths of 18 (), 12 (juvenile), and
seven () inches. One of the turtles hibernating at this place on
November 6 was basking on October 30 in the shelter of some tall
weeds a few feet from the hibernaculum.

Fig. 24. The approximate length
of stay of each known occupant of a den that was examined six times in the winter
of 1955-1956 at the Damm Farm. Most of the occupants used the den as a temporary
shelter and sought permanent hibernacula elsewhere. One turtle left the den for
approximately two weeks and then returned to it for the rest of the winter. The
temperature of the air outside the den (A) and the average body temperature of
turtles in the den (B) are given at the bottom of the diagram for each date the
den was examined. The symbol "J" represents a juvenal turtle.

In general, body temperatures approximated the temperature of
the soil around the turtle. Body temperatures tended to be slightly
higher than soil temperatures in November and December but were
slightly lower than soil temperatures in the months of February and
March. The lowest body temperature recorded for any turtle that
[Pg 616]
survived a winter was 2.7 degrees, taken from an adult female on
December 26, 1955. Body temperatures one to three degrees
higher were common in the coldest part of the winter. Turtles in
shallow hibernacula, like those observed in wooded areas at the
Reservation, are probably subjected to freezing temperatures at
least for short periods but I have no records of body temperatures
this low, except where they were induced experimentally. Turtles
exposed to temperatures of zero degrees or slightly lower would
retain enough heat to survive without freezing for a period of
several hours or even a day if well insulated. A temperature
gradient exists within the body; cloacal temperatures, for example,
differ from temperatures deep in the colon and temperatures in the
dorsal and ventral parts of the body cavity (taken by manipulating
the bulb of the thermometer while it was in the colon) differ from
one another. Probably, therefore, some parts of some turtles—probably
the top of the shell or the extremities—freeze in winter
without causing the death of the turtle. Ewing (1939:91) found a
female of T. carolina, just emerging from hibernation, that had lost
some scutes from its carapace; he found the missing scutes in the
hibernaculum and attributed their loss to severe temperatures in
the winter of 1933-34.

The incidence of mortality due to freezing is unknown for most
species of reptiles. The observations of Bailey (1948) on DeKay
snakes (Storeria dekayi) and Legler and Fitch (1957) on collared
lizards suggest that rates of mortality are high in dormant reptiles.
Bailey (op. cit.) suggested that winter mortality might act as a
natural check on snake populations. Neill (1948a:114) thought
more box turtles (T. carolina) were killed in Georgia by cold
weather in late autumn than "… by all other factors together,"
and that this winter mortality acted as an effective check on population
levels. Neill reported that many turtles left their burrows in
late autumn and began to forage; if the temperature dropped
suddenly, the turtles became "… too torpid to dig" and froze.

If ornate box turtles are occasionally caught in the open by a
sudden cooling of air temperature, it would occur at a time of year
when temperatures would approximate freezing but would drop
not far below this level; laboratory and field records show that
adults could probably survive these low temperatures overnight
and warm up sufficiently on the following day to seek adequate
shelter. Box turtles deepening their burrows in winter do so at
body temperatures somewhat lower than 10 degrees (near the
minimum temperature at which co-ordinated activity was observed
[Pg 617]
in the laboratory); turtles found in the open in late October were
known to burrow into the ground at body temperatures of approximately
15 degrees.

Emergence from hibernation usually occurs in April but in some
years a few turtles may emerge as early as the first week of March.
Emergence is stimulated by temperature and humidity. Fitch
(1956b:438) stated that emergence was delayed until "…the ground
has been sufficiently moistened and until air temperatures have reached
at least 26°." Box turtles at the Reservation
emerged on April 21 in 1954 and from April 16 to 17 in 1955.
William R. Brecheisen found recently emerged box turtles in
Anderson County on April 2, 1955, and March 6, 1956.

Turtles were found facing upward in their hibernacula in early
March. As the temperature of the soil rises, they move slowly
upward, usually following the route by which they entered. They
remain just below the surface of the soil for a week or two before
actually emerging; this final phase of emergence is probably hastened
by spring rains that soften the soil. Activity may be sporadic
after emergence if the weather is cold.

A number of box turtles at the Reservation emerged in a cold
rain in 1954 when the temperatures of the air and ground were
16 and 13 degrees, respectively, but remained inactive for several
days afterward. In 1955 the air and ground temperatures were
higher (28° and 17°, respectively) on the day of emergence and
box turtles became active almost immediately.

Published information on the food of T. ornata consists of a
few miscellaneous observations. Cahn (1937:103) opened five
stomachs that contained partly digested vegetable matter but no
insects or other animal food: Ortenburger and Freeman (1930:187)
noted that grasshoppers were a main part of the diet of T.
ornata in Oklahoma and that turtles displayed unsuspected agility
in catching them. Those authors also saw turtles eating caterpillars
and robber flies. Strecker (1908:79) stated that "The natural diet
of this species consists of vegetable matter and earthworms." Norris
and Zweifel (1950:3) observed the feeding habits of captive
T. o. luteola. Coyote melon (Cucurbita foetidissima) was eaten
with reluctance but a collared lizard (Crotaphytus collaris) was
quickly devoured. Tadpoles of Scaphiopus hammondi were caught
in a small pool and eaten. Adults of the same species were rejected
after being caught; box turtles were seen wiping their mouths
[Pg 618]
after rejecting adult toads. The authors suggested that T. o. luteola
is an important predator of Scaphiopus hammondi, since the two
species occur together in many areas and the emergence of both
is controlled to a large extent by rainfall. One individual of
luteola was seen eating a dead box turtle on a road.

Captive individuals of T. ornata, observed in the present study,
ate nearly every kind of animal and vegetable food given to them.
Table scraps, consisting chiefly of greens, various fruits and vegetables,
meat, and cooked potatoes, formed the main diet of turtles
kept in outdoor cages.

A number of persons have told me of ornate box turtles eating
the succulent stems and leaves, and the fruits of various garden
plants; similar incidents probably occur in areas of native vegetation.
J. Knox Jones told me he saw an individual of T. ornata
eating a spiderwort (Tradescantia sp.) in Cherry County, Nebraska.

Sight-records of foods eaten by box turtles at the Damm Farm
(excluding the many records of individuals foraging in dung or
eating mulberries) were for grasshoppers, caterpillars, and various
kinds of carrion. Box turtles were often seen eating grasshoppers
on roads in early morning; Sophia Damm told me of frequently
seeing individuals catching grasshoppers in her garden. Ralph J.
Donahue told me that on his farm in Bates County, Missouri, an
individual of T. ornata made a circuit of the lawn each morning in
summer and ate all the cicadas (Magicicada septendecim) found.

Vertebrate remains found in the stomachs of box turtles seem
to result chiefly from the ingestion of carrion. One box turtle ate
a white egg (unidentified) that had fallen from a nest and another
was seen with a blue down feather clinging to its mouth. Several
colleagues have told me of box turtles eating small mammals caught
in snap-traps and Marr (1944:489) reported a similar incident.
J. Knox Jones told me he once found an ornate box turtle in the
nest of a blue-winged teal in Cherry County, Nebraska; the three
eggs in the nest had been broken. The only authentic record of an
ornate box turtle preying on a vertebrate under natural conditions
was one supplied by Ralph J. Donahue who saw an adult catch and
eat one of a brood of bobwhite quail. In many areas where box
turtles are abundant, it is the opinion of local residents that the
turtles decimate populations of upland game birds by eating the
eggs and young of these birds; these opinions result probably from
rare encounters such as the one described by Donahue. I believe
that box turtles at the Damm Farm were sometimes able to catch
young frogs and tadpoles (chiefly Rana catesbeiana and R. pipiens)
[Pg 619]
at the margins of ponds. In autumn literally thousands of young
Rana were present in these places.

Ornate box turtles ordinarily attempt to catch and, without
further examination, to eat, small objects moving on the ground, but
are more critical of stationary objects. Captive turtles, for example,
would immediately chase and seize a grape that was pulled or
rolled slowly across a floor but a stationary grape was examined
and then smelled before it was eaten. Similar observations were
made a number of times with living and dead insects in the field
and in the laboratory. A turtle discovering an object that is of
possible value as food, approaches it closely, turns the head from
side to side (presumably using the eyes alternately to examine the
object), and then, with head cocked at a slight angle, momentarily
presses the nostrils against the object (Pl. 28, Fig. 4). If acceptable
as food, the object is then swallowed whole or taken into the mouth
with a series of bites; large insects are usually broken into several
pieces in the process of being bitten and swallowed. Larger objects,
such as dead vertebrates, are torn to pieces with the beak
and forefeet before they are swallowed. Hatchlings, when fed for
the first time, ignored inanimate foods but eagerly chased mealworms,
catching them usually by the anterior end. The tendency
of the young of certain species of turtles (especially captives) to
be more carnivorous than adults is probably due to the association
of movement with food; recognition of inanimate objects as food is
presumably learned by older individuals.

Mulberries (Morus rubra), when they are abundant, constitute
all or an important part of the diet of ornate box turtles. On June
4, 1955, William R. Brecheisen and I drove along a road in Anderson
County, Kansas, and stopped at each mulberry tree that we
saw beside the road; we found at least one specimen of T. ornata
under nearly every tree. Approximately twenty box turtles were
collected in this manner in a little more than one hour. The heads
and necks of most were stained dark-red from the fruit and, in
some, nearly the entire shell was stained. Dissection of these
turtles revealed that their stomachs were distended to two or three
times normal size with mulberries; no other kinds of food were
found in the stomachs. Some of the turtles voided purplish-black
fluid from the cloaca when we handled them; the color of the
fluid presumably resulted from mulberries.

Several turtles were observed through binoculars as they foraged.
Individuals snapped or lunged periodically at objects on the ground
along the route of travel. Upon reaching an area where cow dung
[Pg 620]
was abundant, a turtle would move directly to a pile of dung and
begin tearing it apart with the forelegs or burrowing into it.
Turtles most often foraged in cow dung that had a superficial,
dried crust. The invertebrate fauna of older dung was probably
greater than that of fresh dung. Adult and larval insects were
eaten, along with quantities of dung, as they were uncovered.
Sometimes box turtles chased and caught larger insects that ran
a foot or more away from the pile of dung; the turtles could cover
the distance of one foot with three or four quick steps. Depressions
made by box turtles in cow dung, as well as drier cow dung
that had been more completely dissected, were regarded as characteristic
"sign" of T. ornata at the Damm Farm and in other areas
studied (Pl. 26). Several persons have told me of box turtles
"eating cow dung"; these reports, most of them made by competent
observers, probably result from observations of box turtles ingesting
cow dung incidentally, along with some unseen item of food.

Contents of stomachs were analyzed. Scats and contents of
lower digestive tracts, although obtained in large quantity, were
unsuitable for analysis because of the fragmentary nature of the
foods they contained. Relative amounts of various kinds of foods
in stomachs were estimated; volume was determined by displacement
of water or fine shot.

Twenty-three stomachs of adults were selected at random (except
for the fact that empty stomachs were discarded) from more
than a hundred specimens collected in Douglas County, Kansas,
in the period from June, 1954, to June, 1957; the sample included
stomachs obtained in nearly all the months of the season of activity.
Kinds of foods in stomachs did not differ significantly in regard to
the sex of the turtles or to time of year. The stomach of each of
two juveniles (included in Table 6) contained a greater variety of
animal food than did the stomach of any adult, but no kind of
animal was eaten by the juveniles exclusively.

Each of the 23 stomachs contained animal matter and, in addition,
all but two contained at least some plant material from dung,
which constituted up to 20 per cent of total stomach contents.

Insects were present in each of the 23 stomachs and constituted
the bulk of the animal matter; beetles, caterpillars, and grasshoppers
(ranked in descending order) were the kinds occurring
most frequently and constituting the largest average percentages
of total stomach-contents. Most of the beetles were scarabaeids
and carabids; the bulk of the caterpillars were noctuids and arctiids.
Grasshoppers, with one exception, were of a single species, Melanoplus
differentialis. It is noteworthy that two of the kinds of
insects frequently eaten (differential grasshoppers and noctuid
caterpillars) are of economic importance in that they damage
crops.

[Pg 621]

[Pg 622]

Snails, sowbugs, and the one individual of crayfish found in
stomachs were kinds that could be expected to occur in moist
grassland or in wooded stream courses. Mulberries were present
in one stomach and fragments of bird's-nest fungi (Cyathus striatus)
were present in another. Carrion consisted of remains of mammals
and birds; the only identifiable items were bones of the eastern
cottontail (Sylvilagus floridanus) and a chicken. Stones up to
seven millimeters in diameter were found in many stomachs; stones
constituted as much as half of total stomach-contents. Presumably
the stones were accidentally swallowed when food was taken from
the ground.

The few adequate reports on dietary habits of T. carolina (Allard,
1935:325-326; Carr, 1952:147, 150, 152, 153; Stickel, 1950:361;
Surface, 1908:175-177) indicate that the species is omnivorous but
that individuals tend to be herbivorous or carnivorous at certain
times. Ornate box turtles resemble T. carolina in being opportunistic
feeders but rely on insects as a staple part of the diet. In this
respect the ornate box turtle seems to differ from all other kinds
of box turtles in the United States and it is probably unique in its
habitual utilization of dung communities as a source of food.

[Pg 623]

Ornate box turtles were probably more numerous on the Damm
Farm than any other kinds of reptiles, excepting skinks (Eumeces
fasciatus and E. obsoletus), and were by far the most conspicuous
element of the reptilian fauna.

The 194 box turtles that were marked at the Damm Farm were
captured a total of 437 times. Seventy-nine (41 per cent) individuals
were recaptured at least once, 49 (25 per cent) twice, 29 (15
per cent) three times, and 20 (10 per cent) were recaptured at least
four times. Only three individuals were recaptured more than eight
times. The greatest number of recaptures for a single individual,
an old female, was 23.

In all, 185 turtles (95 per cent of total recorded at Damm Farm)
were captured on the pasture. Of these, 73 were in the northwest
corner area, 44 in the house pond area, and 35 in the southern ravine
area. The density of the population at the Damm Farm, considering
the entire area, was .88 turtles per acre; for the woodland
area alone, density was .41 turtles per acre and for the pasture alone,
density was 1.49. Acreage and population density in the northwest
corner, house pond, and southern ravine areas were respectively, 28
acres with 2.6 turtles per acre, 7 acres with 6.3 turtles per acre, and,
17 acres with 2.6 turtles per acre. The densities noted above for the
wooded area and for the entire Damm Farm are low as a result of
incomplete sampling in the wooded area. Estimates of population
density for the subdivisions of the pasture seem more closely to
approach the true population density in areas of favorable habitat.

Fewer unmarked turtles were captured as the study progressed,
but they were still being captured occasionally when field work was
terminated. In order to estimate the number of turtles in the population
at the Damm Farm the "Lincoln Index" (Lincoln, 1930)
was used to compare the ratio of marked individuals to total number
of individuals (17:56) in collections for June, 1956, to the ratio
of marked individuals as of July 31, 1955 (87) to total individuals
in the population; the result was 286.

Fitch (1958:78) estimated the population of T. ornata in one area
of the Reservation (including woodland and ungrazed pasture) to
be .076 turtles per acre. Stickel (1950:373) estimated the population
of adult T. carolina to be four to five turtles per acre in favorable
habitat at the Patuxent Research Refuge, Laurel, Maryland;
juveniles comprised less than ten per cent of the population.

Of the 194 turtles marked at the Damm Farm, 103 (53 per cent)
were adult or subadult females, 61 (31 per cent) were mature
[Pg 624]
males, and 30 (16 per cent) were juveniles of undetermined sex.
The ratio of males to females was then, 1.00 to 1.69, and the ratio
of juveniles to adults was, 1.00 to 6.47. Eighteen of the 194 individuals
were juveniles less than 90 millimeters in plastral length
and only six had plastra less than 60 millimeters long (Fig. 25).
The unbalanced ratio between males and females may result, in
part, from sexual differences in habits. The studies of Carr (1952:9),
Fitch (1954:140), Forbes (1940:132), Legler (1954:138), and
Risley (1933:690), have shown, however, that unbalanced sex ratios,
with females outnumbering males, are found in several species
of reptiles, especially in turtles.

Records for 540 adult T. ornata collected at the Damm Farm, the
Reservation, and on roads in eastern Kansas, show that females outnumber
males just before and during the nesting season and again
in late autumn (Fig. 26). The high incidence of females in May,
June, and July, can be explained by their more extensive movements
associated with nesting in these months. I have no explanation for
the increased number of females captured in late autumn. In April
and August, the only two months in which males were more abundant
than females, the samples were small. The number of juveniles
collected was too small to allow any trustworthy conclusions concerning
their seasonal incidence; a few juveniles were taken in
nearly all the periods in which adults were active.

Risley (1933:690), studying Sternotherus odoratus in Michigan,
found an over-all sex ratio of 1.0 male to 2.3 females; the percentage
of females in collections ranged from 50 to 71 per cent in April and
most of May and rose to 83 and 85 per cent in late May and mid-June,
respectively.

The infrequency with which hatchlings and small juveniles of
ornate box turtles are observed is well known to naturalists. Several
of my colleagues who are expert field observers and who have lived
in areas where ornate box turtles are abundant, have never seen
hatchlings; many other persons have seen only one or two. Rodeck
(1949:33), noting the abundance of coleopterous insects in the scats
of captives and the rarity of individuals of all age groups during dry
periods in Colorado, commented, "It is possible that the young are
even more subterranean than the adults. Perhaps they spend their
early years in rodent or other burrows where there is a fairly abundant
insect fauna. Increasing size might force them to the surface
for feeding, with a daily return to a burrow for resting and protection."

[Pg 625]

Fig. 25. Composition of the
population of T. o. ornata at the Damm
Farm based on the 194 individuals marked there in the years 1954 to
1956. Individuals smaller than 100 mm. ordinarily could not be sexed
accurately and are shown as open bars. Open bars in the groups larger
than 100 mm. are for females, whereas solid bars are for males.

My own experience in the field has shown that small examples of
T. ornata are not so rare as previous workers have believed. Small
box turtles occupy the same microhabitat as do the adults and seem
not to be more aquatic or subterranean in habits. Juveniles are
found in burrows, in marshy areas, and in other sheltered places, but
so are adults. Most of the juveniles that I found were in open
situations where adults were abundant, sometimes within several
inches of a place where an adult was feeding or basking. Nearly
every one of the smaller turtles was discovered when I was closely
scrutinizing some other object on the ground; sometimes juveniles
were actually touched before being seen. Most juveniles were
covered with cow dung or mud and blended so well with the substrate
that they were detected only when they moved. It is likely
that only a small number of the young box turtles present in an area
is ever actually observed. Young are more vulnerable to predation
and injury because of their small size, soft shells, and immovable
plastra. They evidently rely, to a large extent, on inconspicuousness
for protection.

[Pg 626]

Fig. 26. The seasonal abundance
of females of T. o. ornata based on 540 adults captured at the Damm Farm,
the Reservation, and on roads in eastern Kansas, in the years 1954 to 1956.
Records are grouped in periods of 30 days, the periods beginning with the dates
shown at the bottoms of the bars. Juveniles are not considered. Numbers at the
top of each bar indicate the size of the sample (both sexes) and give an
approximate indication of relative seasonal abundance of adults, except for August,
when little field work was done.

The only previous study of movements of T. ornata is that of
Fitch (1958:99-101). He recovered 14 marked T. ornata at the
Reservation a total of 30 times, the period between recaptures varying
from one to seven years. He reported that the average radius
of home range was 274 feet (for an area of approximately 5.4
acres), excluding a single (presumably gravid) female that moved
1830 feet in 53 days.

Although published information on T. ornata is scant, a considerable
amount of information is available concerning its congener,
T. carolina. The classic studies of Stickel (1950) on it constitute
the most complete account of populations and movements for any
reptile or amphibian, and probably, for any vertebrate. She found
the average home range of adults to be 350 feet in diameter. Home
ranges were not defended as territories and nearly all individuals
were socially tolerant of one another. Movements (studied by
means of a thread-trailing device) were characterized by frequent
[Pg 627]
travel over the same routes within the home range. Some turtles
concentrated their activities in only one part of the home range,
moving subsequently to another part, and some turtles had two
ranges between which they traveled at varying intervals. Females
ordinarily left their home ranges to nest.

Other noteworthy, but less detailed, studies of populations of
T. Carolina are those of Breder (1927) who found evidence of home
range and homing behavior, and of Nichols (1939b) who, after
observing a marked population on Long Island over a period of
twenty years, found evidence of homing behavior and estimated
normal home range to be approximately 250 yards in diameter.
Numerous shorter papers such as those of Schneck (1886) and
Medsger (1919) document the tendency of T. carolina to remain in
restricted areas over long periods.

Important studies that indicate the presence of home range and
homing behavior in other chelonians are those of Cagle (1944) on
Pseudemys scripta and Chrysemys picta, and of Woodbury and
Hardy (1948) on Gopherus agassizi. Grant (1936) and Bogert
(1937) have also indicated that movements of individuals of Gopherus
agassizi are restricted to limited areas.

Ornate box turtles moving forward over even terrain hold the
plastron a quarter to a half inch above the ground and keep the
head and neck lowered and extended. Each foreleg is brought
forward and the humerus points nearly straight ahead when the
foot touches the ground. Nearly all of the palmar surface is initially
in contact with the ground but as the body is brought forward
and the humerus swings outward, only the claws, and finally, only
the two inner claws are in contact with the ground. Of the hind
feet, the medial surfaces are the principal parts that touch the
ground but some traction is derived from the hind claws at the beginning
of each cycle of the hind leg. Under normal conditions,
box turtles move slowly and pause to rest and examine their surroundings
every few feet. When resting, the plastron is in contact
with the ground, the legs relaxed, and the head and neck are extended
upward. Some turtles seeking shelter from the heat of sunshine
walk rapidly for a hundred feet or more without pausing.

Turtles seen feeding under natural conditions displayed remarkable
agility in making lunges, consisting of one or two short steps
and a thrust of the head, at moving objects. Turtles kept in my
[Pg 628]
home were able, after being conditioned to hand-feeding, quickly
to intercept a grape rolled slowly across a linoleum-covered floor.

Frederick R. Gehlbach told me that, of several species of captive
turtles observed by him, T. ornata characteristically walked with
the plastron held well above the substrate, as did Gopherus berlandieri,
but that T. carolina (specimens from the northeastern U. S.)
dragged their shells as they walked. Apparently T. carolina in
Kansas (currently referred to the subspecies triunguis) differs
somewhat in gait from populations in the eastern part of the range;
several individuals of T. carolina from Kansas that I observed in
captivity, kept their plastra raised well above the smooth, hard
substrate over which they walked.

Box turtles at the Damm Farm were able easily to climb ravine
banks that sloped at an angle of 45 degrees and, with some difficulty,
could climb banks as steep as 65 degrees. Most individuals,
however, were reluctant to walk directly downward on banks as
steep as 45 degrees. Several individuals were seen to lose footing
when climbing up or down a steep bank and to roll or slide to the
bottom. Ordinarily, T. ornata is able to climb over a sheer surface
as high as its shell is long, provided the surface is rough enough to
give some traction to the foreclaws. The claws of first one, then
the other forefoot are placed over the top of the barrier and then
a hind foot, extended as far forward as possible, secures a hold as
the turtle goes over the barrier.

A number of observations on speed were made in the field
where distance traveled and time elapsed were known approximately.
Speeds ranged from 20 to 100 feet per hour in the course
of foraging. Higher speeds (400 or more feet in one hour) were
for turtles moving along pathways or seeking shelter. Gould
(1957:346) observed somewhat faster speeds in T. carolina (192
feet per hour in cloudy weather and 348 feet per hour in sunny
weather); he observed individuals that had been removed from
their normal home ranges.

Individuals of T. ornata that were placed in water swam moderately
well but were clumsy in comparison to individuals of more
aquatic emyids such as Pseudemys and Chrysemys. Box turtles
were never observed to swim voluntarily, although they were frequently
found in shallow water. On several occasions I confronted
individuals at the edge of a pond so that the only unblocked route
for their escape was through deeper water; nearly always these
individuals attempted to crawl past me, to crawl away in shallow
[Pg 629]
water parallel to the shore, or to hide in soft mud at the edge of
the water. Box turtles floated high in the water with the dorsal
side upward and had little difficulty in righting themselves when
turned over. The head and neck are extended and submerged
when the turtle is swimming; forward progress is interrupted every
few moments to elevate the head, presumably for purposes of
breathing and orientation. The shell is never submerged. The
swimming of T. ornata is in general like that of Pseudemys or
Chrysemys that have become dehydrated after long periods out
of water and cannot submerge. These more aquatic turtles, however,
quickly overcome their bouyancy, whereas examples of T.
ornata, even if left in water for several days, are unable to submerge.
Clarke (1950) saw an ornate box turtle swim a 60-foot-wide
stream in Osage County, Kansas; his description of swimming
agrees with that given above.

The meager swimming ability of T. ornata is of apparent survival
value under unusual conditions and enables T. ornata to
traverse bodies of water that would act as geographic barriers to
completely terrestrial reptiles; however, swimming is a mode of
locomotion seldom used under ordinary circumstances.

Gehlbach (1956:366) and Norris and Zweifel (1950:2) observed
individuals of T. o. luteola swimming in temporary rain pools and
small ponds in New Mexico; the two authors last named saw an
individual quickly enter a pond and dive beneath the water after
being startled on the bank. Several of my colleagues, in conversation,
have also reported seeing T. o. luteola in small bodies of
water in the southwestern United States.

The daily cycle of T. ornata consists basically of periods of basking,
foraging, and rest that vary in length depending upon environmental
conditions. Turtles emerge from burrows, forms, and
other places of concealment soon after dawn and ordinarily bask
for at least a few minutes before beginning to forage; foraging is
combined sometimes with basking, especially in open areas that
are suitable for both kinds of activity. Foraging usually continues
until shelter is sought sometime between mid-morning and noon.
Turtles remain under cover (or continue to forage in shaded
areas) until mid-afternoon or late afternoon when they again become
active. They forage in both morning and afternoon. Study
of travel records of a few of the turtles equipped with trailers
[Pg 630]
suggests that, under normal conditions, activity is slightly greater
in forenoon than in afternoon, but that the converse is true of
gravid females seeking nesting sites. Strecker (1908:79) reported
that captive T. ornata, after developing a feeding reflex, ate and
retired until feeding time next day.

As environmental temperatures rise in summer, the period of
mid-day quiescence is lengthened. In the hottest part of the year,
some turtles remain under cover for several days at a time. In
periods of clear, cool weather at the beginning and end of the
growing season, some turtles remain abroad and bask for most of
the day.

Examination of thread trails showed that activity of all individuals
except nesting females was terminated at dusk. Breder
(1927:236), Allard (1935:336), and Stickel (1950:358) reported a
corresponding lack of nocturnal activity in T. carolina. Terrapene
o. ornata in Kansas, and T. o. luteola in New Mexico (Norris and
Zweifel, 1950:2)—unlike desert tortoises, Gopherus agassizi, which
are active at night in hot weather (Woodbury and Hardy, 1948:186)—do
not utilize the hours of darkness for foraging, even in the
hottest part of the year.

Data obtained by mapping the movements of turtles that were
equipped with trailing devices made it possible to compare distances
traveled in the course of daily activities at different times of
the year. Some of these data are expressed graphically in Figure 27.
It should be noted that movement at all times in the season
of activity was uneven; that is to say, an individual would move
several hundred feet each day for a period of several days, and
then, for an interval of one to several days, move only a few feet
from one shelter to another, or not move at all. Such periods of
rest could not be correlated definitely with environmental conditions;
some individuals were inactive on days that were probably
ideal (in terms of moderately warm temperatures and high humidity)
for activity of box turtles. Analagous rest periods were
noted in T. carolina by Stickel (1950:358).

Two males of T. ornata that had been removed by me from their
normal home ranges traveled the longest average distance per
day (429 feet). Gravid females in June traveled the next longest
average distance per day (363 feet). The average distances traveled
per day by non-gravid females in June (226 feet) and July
[Pg 631]
(260 feet) and by males (within their known home ranges) in June
(289 feet) were thought to approximate normal amount of movement
under average environmental conditions. Average distance
traveled per day by females in October (152 feet) was shortest
because of frequent and extended rest periods. Nevertheless, in
October actual distances traveled on days of activity tended to be
longer than in any other month. A gravid female traveled farther
in a single day than any other individual of T. ornata observed;
she moved along a rock fence for approximately 700 feet, then
left the study area and moved, in a nearly straight line, 1,200 feet
across a cultivated field. Then the thread on her trailer was expended.
The total distance moved, therefore, was at least 1,900
feet and probably more.

Fig. 27. Average distances
traveled per day by males and females at different times of the year,
determined by mapping of thread trails at the Damm Farm. The diagram for
"homing males" represents the distances traveled by two males
removed from their normal home ranges to test homing ability. The data
presented are for an aggregate of 136 days of trailing. Vertical and
horizontal lines represent, respectively, the range and mean. Open and
solid rectangles represent one standard deviation and two standard errors
of the mean, respectively.

An adult male at the Reservation traveled 2,240 feet in the 36-day
period from October 16 to November 20, 1954, mostly on a wooded
[Pg 632]
hillside. Eleven forms found along the route of the turtle's travels
indicated that movement took place on roughly one out of three
days in the elapsed period and demonstrated the sporadic nature
of movements in autumn. The turtle remained active for an undetermined
time after November 20.

Data obtained from trailing and various methods of recapture
at the Damm Farm indicated that each individual used only a small
part of the total study area in the course of daily activities and
tended to remain within a restricted area for a long time.

The number of recaptures of no individual was great enough to
permit application of refined calculations of size of home range as
described by Odum and Kuenzler (1955). For individuals that
were recaptured six or more times, or individuals for which adequate
trailing records were available, the area enclosed by a line
joining the peripheral points of capture was considered adequately
representative of the home range of that individual, unless recaptures
were all within a few feet of each other or lay in an approximately
straight line. If less than six records of recapture were
available, home range was estimated, in the manner described by
Fitch (1958:73), by averaging the distance between successive
points of recapture and letting this average represent the radius of
home range; the actual area of home range was determined by the
formula, π(R)², for the area of a circle.

Size of home ranges of males and females did not differ significantly
and data for the two sexes were combined in the final
analysis. The average radius of the home ranges of 44 adults (captured
a total of 146 times) was 278 feet (extremes, 71 to 913) when
computed by measuring the distance between successive captures;
the average area of these home ranges was 5.6 acres. Data from
10 turtles that had been recaptured only once were combined with
data from 34 turtles that had been recaptured more than once when
it was found that the average size of home range in these two groups
did not differ significantly. Data concerning the home ranges of
eight of the 44 individuals were sufficient to permit actual measurement
of home ranges with a planimeter; home ranges of these eight
individuals had an average area of five acres (extremes, 1.2 to 10.2).

A minimum home range could theoretically consist of the smallest
area in which adequate food and shelter were available. Under
favorable conditions a turtle could stay in an area ten to twenty
feet in diameter. Although several such favorable small areas
[Pg 633]
existed on the Damm Farm, box turtles seldom stayed in one for
more than a day or two. Seemingly, therefore, factors additional to
food and shelter influence size of home range. At the Damm Farm
these additional factors seemed to be: rock fences that acted as
physical barriers; areas that were cultivated, barren, or otherwise
unfavorable, acting as ecological barriers; and, cowpaths and ravines
that offered relatively unobstructed routes along which box turtles
tended to move.

One subdivision of the main pasture, the northwest corner area,
is an example of a relatively small natural area in which many individual
box turtles had home ranges. This tract of 28 acres was
roughly triangular and was bordered on two sides by rock fences
that contained no gates or other passageways. On its third (southeastern)
side the area sloped into a deep ravine. Habitat in this
subdivision of the pasture (as well as in the other two subdivisions)
was especially favorable for box turtles because of permanent water,
rocky slopes, ravines, and several fruit trees. Box turtles usually
foraged near the rock fences and the ravine (where dung was more
abundant than in other parts of the area), and tended, as they
foraged, to move parallel to these barriers. Turtles crossing the
area eventually came either to one of the fences or the ravine.
Therefore, most of the turtles in the northwest corner area
eventually completed a circuit of the area. Turtles that came to
the ravine tended to move along its bottom or sides. Several turtles
were known to cross the ravine and to forage in the grassy area on
its southeastern side. These turtles usually re-entered the ravine
by way of smaller side-ravines. Of 22 box turtles known to have
home ranges in the northwest corner area, only two individuals
(both gravid females) were known to leave the area in the period
in which observations were made.

Two other subdivisions of the main pasture—the house pond
area and the southern ravine area—although not so distinct as the
northwest corner area in terms of limiting barriers, nevertheless
constituted separate areas of favorable habitat, each of which contained
a number of individual home ranges. Although the two
areas were not far apart, but little movement was observed of turtles
from one area to the other. The home range of only one turtle, an
adult female, was known to include parts of both areas.

Unbroken expanses of tall grass seem not to be optimum habitat.
The crest of the hill at the Damm Farm (Pl. 17, Fig. 1) was an area
of more or less homogeneous grassy habitat. Turtles were seldom
[Pg 634]
found on the crest of the hill although this area was as thoroughly
searched for turtles as any other area. Known home ranges of
nearly every individual observed were on either one of the sides of
the hill but not on both sides.

At several places on the border of the pasture, turtles were able
to move freely into cultivated areas but seldom did so except for
nesting. Trailing records show that most of the turtles that entered
one of the cultivated areas returned again to the pasture.

Ornate box turtles seem to find places of shelter by trial and error
along regularly used routes of travel in their home ranges. The
individuals that I studied never returned to the same forms, and
seldom returned to the same natural burrows and dens. Probably
foraging, basking, and watering sites are found also by trial and
error.

Stickel (1950:375) placed considerable importance on the occurrence
of transient turtles in populations of T. carolina; in estimating
population density, she added to her study area a peripheral strip,
half as wide as the average, estimated home range, to account for
turtles that had home ranges only partly within the study area. The
study area used by Stickel had no natural boundaries, as habitat
conditions on all sides were essentially the same as those of the
study area itself. The pasture at the Damm Farm, on the contrary,
is a relatively isolated area of natural grassland, bordered by rock
fences and cultivated fields. I believe that most of the box turtles
found on the pasture were permanent residents there. Individual
box turtles at the Damm Farm seemingly occupied but one home
range and it did not change from year to year. Populations of T.
ornata in areas less isolated than the Damm Farm, like the populations
of T. carolina studied by Stickel (loc. cit.), could be expected
to have a higher percentage of transient individuals and individuals
with multiple or changing home ranges. Henry S. Fitch told me
that he considered most of the individuals of T. ornata that were
captured only once at the Reservation were transients.

Several females at the Damm Farm traveled long distances from
their home ranges to nest but other females nested within their
known or estimated home ranges. Seemingly a complex of environmental
factors, including soil texture, weather, availability of water,
and possibly the urge for random wandering in the breeding season,
governs the distances traveled by gravid females and the ultimate
selection of a satisfactory nesting site. Females, because of their
more extensive travels in the nesting season, seem more likely than
[Pg 635]
males to have multiple or changing home ranges. Males of T. ornata
did not noticeably alter the extent or pattern of their movements in
the breeding season. Hibernacula, unlike nesting sites, were within
the known or estimated home ranges of all individuals studied.

Fig. 28. The movements of an
adult (non-gravid) female of T. o. ornata in the house pond area at the
Damm Farm during a period of 24 days in July, 1955 (solid line), and a period
of three days (broken line) in July, 1956. Solid dots represent the points
where the turtle was found as her thread trail was mapped; hollow symbols
represent points of recapture when no trailing thread was attached to the turtle.

The actual home range of almost every individual studied, even
of those individuals for which the most data were available, probably
differed at least slightly from the observed or estimated home
range. One adult female, for example, was captured six times in
[Pg 636]
two years within a radius of approximately 50 feet. Another female
was found 2780 feet from her last point of capture. These last
two records were regarded as unusual; when they were grouped
with records of the 44 individuals mentioned above, the average
radius of home range for the entire group was much larger (327
feet).

Fig. 29. The movements of a
gravid female of T. o. ornata in the southern ravine area at the
Damm Farm in a period of ten days in June, 1956. Her movements were, for
the most part, in and around several ravines (shown on map by broken lines)
where she was searching for a nesting site. For explanation of symbols see
legend for Fig. 28.

Gould (1957) reported that 22 of 43 T. carolina moved in a homeward
direction when they were released in open fields up to 5.8
miles from their original points of capture. Turtles oriented themselves
by the sun; homeward headings were inaccurate or lacking
on overcast days and, light reflected from a mirror caused turtles
to alter their courses. Seven of ten turtles released more than 150
miles from home headed in directions that corresponded most nearly
to the headings last taken (at release-points near home base) and
did not necessarily correspond to the direction of home. Gould's
studies point out that box turtles perhaps practice a kind of "solar
navigation." His work raises the question of whether the movements
of box turtles are guided by the sighting of local landmarks
or whether such landmarks alter the course of movement only when
acting as barriers.

[Pg 637]

In the present study two experiments were made to determine
the homing ability of T. ornata. An adult male, taken from his normal
home range in the house pond area and released 1200 feet
away in the southern ravine area, traveled a generally northward
course (not northeastward in the direction of home) for five days,
moving a distance of approximately 1900 feet. His detached trailer
was recovered several days later 740 feet southeast of the last
known point in his travels (a distance that could have been covered
in two days) and 150 feet from the point of original capture;
he had returned to his home range by a circuitous route in a period
of approximately seven days. Another adult male, captured in
the southern ravine area, and released in the house pond area
1900 feet away, traveled on a course that bore approximately 25
degrees north of true homeward direction; after five days he was
approximately 600 feet north of the original capture point. He
then began a northeastward course that took him back to the
house pond area where he remained for several days; no further
data are available for this individual. It is significant that the
homing males discussed above traveled greater average distances
per day (based on records for nine days of trailing) than any
of the other turtles studied (Fig. 27). Fitch (1958:101) released
an individual one half mile from where he captured it and, one
year later, recovered the turtle near the point of release.

Ornate box turtles are solitary except during periods of mating.
Meetings with other individuals in the course of foraging, basking,
or seeking shelter, are fortuitous and have no social significance.
A broad overlapping of home ranges of both sexes at the Damm
Farm suggests that box turtles do not intimidate other individuals
in the home range or exclude them from it. No instances of fighting
were observed.

Allard (1935:336), Perm and Pottharst (1940:26), and Latham
(1917) recorded instances of fights between individuals of T. carolina;
in the latter two instances fights were between males. Stickel
(1950:362) observed an incident between two males that may have
been a fight; however, she was of the opinion that fights rarely
occur in nature and that box turtles do not defend territories.
Evans (1954:23-25) considered the behavior of T. carolina reported
by Perm and Pottharst (loc. cit.) to represent "territoriality."
He found "… a true hierarchy…." existing between
[Pg 638]
four captive males of T. carolina and another between three captive
females of the same species; young individuals in the group raised
their social level in the hierarchy after receiving experimental
doses of male hormone. Evans (op. cit.:25) pointed out that true
tortoises (family Testudinidae) have a more complex pattern of
social behavior than do emyid turtles.

Observations made with binoculars from the vantage point of a
blind provide the only information that I have concerning the
reactions of box turtles to one another under natural conditions.
Turtles foraging in a bare area were not startled by the approach
of other turtles, and turtles moving across the area seemed to take
no notice of turtles already there, regardless of whether these
turtles were moving or not. Adults and subadults behaved in
approximately the same manner.

Individuals traveling or foraging in rough terrain or in grassy
areas probably are unable to see each other even when they are
close to one another. Conversely, box turtles can see each other
and are surely aware of each other's presence in bare, flat areas.
These facts suggest that no social hierarchy exists in T. ornata. On
one occasion an adult male and a juvenile (hatched the previous
autumn) were found foraging next to one another on the same
pile of cow dung.

When an individual became motionless in an attitude of wariness
after having detected me in my blind, its behavior evoked no
response on the part of other turtles, a few feet away.

Fire, freezing, molestation by predators, and trampling by cattle
or native ungulates are only a few natural sources of injury to
which box turtles have always been exposed. Man's civilization
in the Great Plains, chiefly his automobile and other machines,
have compounded the total of environmental hazards. Automobiles
now constitute a major cause of death and serious injury to
box turtles. Each year thousands are struck on Kansas highways
alone, not to mention the many casualties resulting from mowing
machines, combines, and other farm machinery.

Although grass fires usually occur in early spring or late fall
when box turtles are underground, some turtles are surely killed
by fires and many are injured. In early April of 1955 the pasture
at the Damm Farm was burned. Similar burnings, I discovered,
had occurred both intentionally and accidently in past years at
[Pg 639]
irregular intervals. No deaths or injuries, attributable to fire were
discovered in the course of intensive field work in the spring and
summer of 1955, when the new grass was short and conditions for
finding and marking box turtles were ideal. Badly burned individuals,
if any, may have secreted themselves until their wounds
had healed. In June, 1957, an adult female, that had been burned
severely, was taken from a small puddle in a ravine on the Damm
Farm. The soft parts of her body, excepting her head and neck,
were a nearly solid mass of smooth scar tissue, the scales and
rugosities of the skin being practically obliterated. The tail was
reduced to a mere knob surrounding the anus and dead, exposed
bone was visible on most of the dorsal part of the carapace. Possibly
this female was burned in the fire of 1955. Lack of injury
to the head and neck can probably be accounted for by the additional
protection afforded these parts by the folded forelegs when
the turtle was withdrawn in the shell.

Turtles that are smashed flat on the highway, of course, have
no chance of survival. Highway fatalities are usually the result
either of "direct hits," where the tire of a vehicle passes directly
over the turtle, or of repeated pummeling by subsequently passing
vehicles. The writer, while driving behind other cars that struck
turtles or by sitting beside roads, has observed numerous turtle
casualties. Most are struck a glancing blow by a tire and are propelled
some distance through the air or on the surface of the pavement,
often to the side of the road. Such a blow is usually sufficient
to crack or chip the shell, or at least to scuff away parts of
the epidermal covering. Turtles, so injured, usually survive.

Parts of the shell do not break away easily, even when several
deep cracks are present, and only a little bleeding occurs. A
common injury inflicted on the highway is the wrenching and subsequent
dislocation of the carapaco-plastral articulation. In such
instances the ligamentous tissue joining the two parts is torn extensively.
Under these circumstances the movable shell parts seem
to act as a safety device, giving way under
pressure that would
crack the shell of a turtle with rigid, fixed buttresses. Dislocations
of the carapaco-plastral articulation that have healed are characterized
by abnormally heavy development of ligamentous tissue,
which may elaborate a horny, scutelike substance on its outer surface.

The extent to which serious injury incapacitates a turtle is not
known. Surely open wounds are susceptible to infection and to
[Pg 640]
various kinds of secondary injury; normal activity is probably interrupted
by a period of quiescence, at least in the period of initial
healing.

An injured female had a hole, slightly more than one inch in
diameter, in the right side of the carapace at the level of the second
lateral lamina. A tight, thin membrane stretched between the
broken edges of the opening; this membrane contained no bone
and was covered externally by scar tissue. It was obvious that this
turtle had recovered, at least in part, from a serious injury (inflicted
probably by a piece of heavy farm machinery).

Minor chips, scratches, and abrasions on the shell result from
a variety of sources, some of them mentioned above. Small rounded
pits in the bony shell (shell pitting) due to causes other than
mechanical injury, are found in nearly all kinds of turtles according
to Carpenter (1956), Hunt (1957), and my personal observation.
In T. ornata, however, the condition is less common than in the
specimens of T. carolina described by Carpenter and in the remaining
species of Terrapene that I have examined.

Carpenter (1956:86) came to no conclusion as to the cause of
shell pitting in Terrapene carolina but suggested that a variety of
factors including parasitic fungi, parasitic invertebrates, and simple
shell erosion, might be responsible.

According to my own observations on turtles in the University
of Kansas collections, shell pits range in size and shape from shallow,
barely discernible depressions to deep borings; I suspect that
shell pitting for turtles in general has many causes, some of which
may be of more frequent occurrence in one species than in another.

Hunt (1957:20) presumably was referring to shell pitting by a
more suitable name when he wrote of, "… necrosis …
of mycotic origin." Hunt (loc. cit.) stated that "Of those cases
which have been recently examined, the author found all were due
to the invasion of Mucorales beneath the plates of the epidermal
laminae. This disease is of extremely common occurrence and has
been found in all members of the order but is seldom found in
marine species. Mycosis more frequently occurs on the plastron
than on the carapace." Hunt presented no evidence to support his
statement regarding invasion of the shell by Mucorales.

Evidence that injury to the soft parts of the body is also fairly
common is seen in the many T. ornata with missing feet and legs.
Stumps resulting from amputations are covered with tough, calloused
skin and sometimes by horny tissue similar to that of the
[Pg 641]
antebrachial scales. Amputees are incapacitated only slightly in
normal locomotion if a functional stump remains; probably a cripple
is somewhat handicapped in other functions, such as burrowing,
nest digging (females), and copulation (males). Causes of amputation
are discussed in the section on predators.

Fractures of the limb bones are common. A female from Stafford
County, Kansas (Pl. 29, Fig. 4), showed a typical case of fracture
and subsequent repair; the right fibula had been broken and the
ends dislocated; a great mass of bone joined the repaired break to
the middle of the tibia, giving the entire skeleton of the leg the
appearance of the letter "H." The fibula, shortened by the dislocation,
no longer articulated by its proximal end with the femur;
the tibia probably bore the entire load in the period of repair and
the transverse connection that formed between the bones later
took over the function of the fibula.

There is little doubt that ornate box turtles are stepped on or
trampled by cattle, at least occasionally, but I never observed such
an incident; the predilection of ornate turtles for dung insects and
for moving along cattle pathways brings them to close quarters
with cattle and probably did likewise with native ungulates. A
steer, stepping on a box turtle, could inflict superficial damage to
the shell or cause broken limbs but would probably not crush the
turtle unless on a hard substrate.

Most adults and a few juveniles examined in the field and laboratory
had one or more small injuries on the carapace that had healed
or were undergoing repair. Such injuries almost never occurred on
the plastron. In an injury that was undergoing repair, a small piece
of smooth, whitened bone was exposed where a piece of epidermis
was missing from the shell. One or more edges of the exposed bone
characteristically projected over the surrounding epidermis, making
the bone appear as though it had been driven forcefully, like a
splinter, into the shell (Pl. 29, Figs. 1 and 2). Because of their
curious appearance, small areas of repair were referred to in my
notes as "splinter scars." The position and number of splinter scars
were often recorded as supplementary means of individualizing
turtles in the field.

Splinter scars result from minor abrasions that damage a few
square millimeters of the shell. Larger areas of exposed bone were
noted in only a few specimens. Two turtles at the Damm Farm had
[Pg 642]
bone exposed on more than one-half the surface area of the carapace;
both of these turtles were probably burned in the grass fire of
1955. Ordinarily, a break in the shell does not induce extensive
regeneration of tissues; when shells are damaged by crushing or
cracking, regeneration of epidermis and bone occurs only along
the lines of fracture, unless the broken parts have been dislocated.
Ligamentous tissue develops in some breaks on the plastron, the
broken area remaining slightly movable after healing is completed
(Pl. 24).

Dissection of injured shells revealed the mode of shell regeneration
to be the same whether a large or small portion of the shell had
been damaged. An abrasion may gouge out a small portion of the
shell; burning, freezing, or concussion may kill a portion of the
epidermis and a corresponding portion of bone beneath it without
actually disfiguring the shell. Dead bone and epidermis become
loosened at the margin of the wound. The epidermis sloughs off
soon afterward but the bone adheres to the wound. New epidermis
and new bone, growing from undamaged tissues at the edges of the
wound, encroach on the wound beneath the layer of dead bone.
The piece of dead bone is thereby gradually isolated from the rest
of the shell and is sloughed off when healing is complete. The dead
bone may come off in one piece or slough off gradually at its edges
as healing proceeds toward the center of the wound. The layer of
dead bone protects the wound during the process of regeneration
(Pl. 30). Areas of exposed bone become white and shiny, nearly
enamellike in appearance, as a result of wear on the shell.

The above conclusions, in regard to T. ornata, agree basically
with the findings of Woodbury and Hardy (1948:161-162) and
Miller (1955:116) on regeneration of the shell in desert tortoises
(Gopherus agassizi). Danini (1946:592-4, English summary) made
histological studies on regeneration of the shell in specimens of
Emys orbicularis; he found that new bone trabeculae formed on
the surfaces of undamaged trabeculae at the edge of the wound
and formed also in connective tissue at the center of the wound.
Regeneration of bone was incomplete in some instances where total
extirpation of a portion of the shell had occurred. Regenerated
epidermis was usually thicker than the original scute.

Exposed bone on the shells of turtles that have been injured in
fires, although dead, is unmarked and shows no evidence of being
burned. Exposure to fire kills the growing portions of both the
epidermis and the bone but seemingly does not actually char or disfigure
[Pg 643]
the bone (although the epidermis may be so affected) (Pl.
29, Fig. 3). Injuries from fire result probably from brief encounter
with the fire itself or from more prolonged contact with some surface
heated by the fire. A turtle that remained in a fire long enough to
have its shell charred would presumably have little chance of survival.
Grossly disfigured shells therefore do not result directly from
burns but are due to the gnarled texture of the regenerated bone
and epidermis remaining after the dead portions of the shell have
been sloughed off. Information on injuries from fire was supplemented
by examination of several badly burned specimens of T.
carolina. Their shells were nearly covered with exposed bone and
regenerated epidermis. One specimen was so badly damaged that
the entire anterior rim of its carapace was loose and could be pulled
away easily to disclose a gnarled mass of regenerating bone beneath
it (Pl. 29, Fig. 3). There were areas near the posterior margin of
the carapace of each specimen where regenerated epidermis was
evident but where the bone was seemingly uninjured; the regenerated
epidermis was nearly transparent.

Areas of regenerated epidermis on specimens of T. ornata were
rough in texture and slightly paler than the surrounding scutes.
Color-pattern is not reproduced in the process of regeneration but
irregularly shaped light blotches sometimes occur in the places
where radiations or other distinct markings formerly were present.
A slight depression remains on the shell after regeneration is completed.
I suspect that small injuries may be repaired in the course
of a single growing season but that injuries involving a large part
of the shell may take several years to heal completely. Cagle
(1945:45) reported that a bullet wound in the shell of a painted
turtle (Chrysemys picta) healed completely in approximately 23
months. Danini (loc. cit.) found that regeneration of the shell in
Emys orbicularis was complete in as short a time as 225 days.
Woodbury and Hardy (loc. cit.) stated that small injuries to the
shell of Gopherus agassizi may take as long as seven years to heal.

Two kinds of ectoparasites were found on ornate box turtles
in the course of the present study; larvae of chigger mites (Trombicula
alfreddugesi) were abundant on specimens collected in
summer and, larvae of the bot fly (Sarcophaga cistudinis) were
found on specimens throughout the season of activity, and, in a
few instances, on hibernating turtles. In general, these ectoparasites
[Pg 644]
do little or no harm to ornate box turtles, although heavy infestations
may cause temporary interruption of normal activity or may
even cause occasional death.

Concerning the larvae of T. alfreddugesi, Loomis (1956:1260)
wrote, "In northeastern Kansas, larvae become numerous in early
June (shortly after they first appear), increase in numbers to
greatest abundance throughout late June and July, decrease
slightly in August, become markedly reduced in September, and
only a few larvae (mostly on hosts) remain in October and early
November." He considered T. alfreddugesi to be the most abundant
chigger mite in Kansas and stated (op. cit.:1265) that it is
most common "… in open fields supporting good stands of
grasses, weeds and shrubs, and where moderate to large populations
of vertebrates are present." Loomis listed ornate box turtles
(op. cit.:1261-2) as important hosts of Trombicula alfreddugesi
but noted that box turtles are not so heavily infested as are certain
other reptiles. The two other species of chigger mites that Loomis
(op. cit.:1368) found on T. ornata in Kansas (T. lipovskyana and
T. montanensis) were not found in the present study.

Box turtles were considered to have chigger infestations when
the reddish larvae could be detected with the unaided eye. No
chiggers were seen on turtles in the period from spring emergence
until June 13, 1955. On the latter date a few scattered chiggers
were noted on several individuals and it was on this same date
that the writer received his first "chigger bites" of the year. Numbers
of chiggers increased in the latter half of June and heavily
infested turtles were noted throughout July. No chiggers were
seen on box turtles after mid-September in 1955.

Chiggers were ordinarily found only on the soft parts of the
turtles' bodies. Early in the season infestations were chiefly on
the head and neck. Favorite sites of attachment were the point
where the skin of the neck joins the carapace and on the skin
around the eyes. Later in the season some chiggers could be
found on nearly every part of the body where soft skin was present;
concealed areas of skin, such as the axillary and inguinal pockets,
the anal region, and the inner rim of the carapace (where it joins
the skin of the body), harbored concentrations of chiggers. Juveniles
were relatively more heavily infested than adults and, even
early in the season, had chiggers attached along many of the interlaminal
seams of the shell. Broad areas of soft, newly-formed
epidermis on the shells of juveniles probably afforded a better
[Pg 645]
place of attachment to chiggers than did the interlaminal seams
of adults. The interlaminal seams and transverse hinges of adults
were not infested until the height of the season of chigger activity.
Heavily infested adults, observed in early July, were literally covered
with chiggers; red larvae outlined nearly all the scutes of the
shell, the anus, the mouth, and the eyes. When turtles were picked
up for examination, chiggers could be seen moving rapidly from
one interlaminal seam to another.

Box turtles kept in outdoor pens and in the laboratory did not
long maintain visible infestations of chiggers, even during the time
in summer when turtles found in the field were heavily infested.

A four-year-old juvenile was found nearly immersed in the shallow
water of a pond on July 4, 1955; its right eye had been damaged
by an especially heavy concentration of chiggers. When I
released the turtle, some 50 feet from the pond, it returned to the
water and spent the next four days there. The turtle was probably
in a period of quiescence induced by the eye injury and the heavy
infestation of chiggers; immersion in water could be expected to
help free the turtle of chiggers and to relieve trauma resulting
from the injured eye. Richard B. Loomis told me that larval chiggers
are able to survive under water for several days but that warm
water will hasten their demise.

Infestations of larval bot flies (Sarcophaga cistudinis) were noted
in several turtles at the Damm Farm and, upon closer scrutiny, were
found to be common in preserved specimens from other areas. Larvae
were always found in flask-shaped pockets (Pl. 27, Fig. 2) beneath
the skin; the pockets opened to the outside by a small hole,
the edges of which were dried and discolored. One larva sometimes
protruded from the opening. The inside of the pocket is lined
with smooth, skinlike tissue. Heavily infested box turtles may have
four or five such pockets, each containing one to many larvae. The
most frequent sites of the pockets are the skin of the axillary and
inguinal regions, and the skin of the limbs and neck, especially near
the bases of these members. Subadults were more heavily infested
than older adults; no infestations of hatchlings or small juveniles
were noted.

An adult female, infested with bot fly larvae when she was removed
from her hibernaculum in late October, 1955, bore no trace
of larvae or of the pocket that had contained them when she was
recaptured the following June. According to Rokosky (1948), the
larvae eventually fall to earth and pupate. The individuals of T.
[Pg 646]
carolina studied by him were not re-infested by adult bot flies; one
turtle ate some of the larvae that dropped from its body.

The manner in which box turtles are infested by bot fly larvae
is uncertain. Possibly the eggs are picked up accidentally or laid
on the skin while box turtles are foraging in dung. Belding (1952:841)
classifies the genus Scarophaga as semi-host-specific, depositing
eggs in open wounds.

McMullen (1940), Rodeck (1949), and Rainey (1953), described
individuals of T. ornata parasitized by S. cistudinis. Rokosky
(1948) and Peters (1948:473) reported infestations in T. carolina.
Infestations were the cause of death in the instances noted by Rainey
and Rokosky.

Few first-hand observations on predators of T. ornata are available
and I have found little direct evidence of predation in the
course of this study. In general, adults of the species seem to have
few natural enemies other than man. Several of my colleagues at
the University of Kansas have observed dogs carrying box turtles
in their mouths or chewing on them. Frank B. Cross told me his
dog caught and ate young T. ornata in Payne County, Oklahoma,
and A. B. Leonard once saw a badger carrying one in Dewy County,
Oklahoma. At the Reservation, a freshly killed juvenile was found
beneath the nest of a crow (Corvus brachyrhynchos) and remains
of a hatchling were found in a scat of a copperhead (Agkistrodon
contortrix).

Dr. Fred H. Dale, Director of the Patuxent Research Refuge,
Laurel, Maryland, kindly furnished photostatic copies of cards, from
the Division of Food Habits Research of the U. S. Fish and Wildlife
Service, recording the instances in which Terrapene ornata
was listed as a food-item. In one instance the stomach of each of
two nestlings, in the same nest, of the White-necked Raven (Corvus
cryptoleucus) in Terry County, Texas, contained remains of recently
hatched ornate box turtles; the remains of one turtle made
up 64 per cent of the contents of one stomach, and parts of three
turtles made up 80 per cent of the contents of the other stomach.
Each of two stomachs of the coyote (Canis latrans) from Quay
County, New Mexico, contained a "trace" of ornate box turtle.

Wild carnivores known to occur on the Damm Farm were raccoons
(Procyon lotor), striped skunks (Mephitis mephitis), badgers
(Taxidea taxus), and coyotes (Canis latrans); all were suspect as
predators of ornate box turtles.

[Pg 647]

On December 10, 1953, ten dead box turtles (eight adults and
two juveniles) were discovered at the top of a cut bank on the
Damm Farm, within a few feet of a burrow that was used at least
part of the time by a striped skunk. The condition of the turtles
suggested that they had lain in the open for several weeks. The
heads and legs were missing from most of the turtles and tooth
marks were discernible on several of the shells. A logical explanation
of this occurrence is that the turtles, using the burrow as a
hibernaculum, were ousted by a predator that also inhabited the
burrow. Turtles moving about sporadically in late autumn may
be quickly chilled by a sudden drop in temperature and therefore
be more susceptible to predation than at other times of the year.
Two of my colleagues at the Museum of Natural History informed
me that they had observed similar concentrations of dead T. ornata
in winter.

In July, 1952, H. B. Tordoff collected eight shells of juvenile T.
ornata in a dry creek bed near Sharon, Barber County, Kansas.
Some of the shells had small tooth-punctures. The stream bed
habitat and the appearance of the tooth punctures tended to incriminate
raccoons as predators. Raccoons, more than any other
carnivore mentioned above, possess the manual dexterity necessary
to pry open the shell of a box turtle and bite away the soft parts.
Badgers and possibly coyotes are probably the only local carnivores
(excluding large dogs) that could crack open the shell of an adult
turtle by sheer force.

Adults of T. ornata, since they occasionally molest small juveniles,
must be considered in the category of predators. When captive
adults and juveniles were fed from the same container in the
laboratory, the turtles occasionally bit one another accidently. Serious
injury to the young was prevented by watching the adults
closely and moving them away when they caught a smaller turtle
by the leg or head. Similar accidents presumably occur in nature;
juveniles and adults were sometimes found feeding side by side.
William R. Brecheisen told me that adults kept in a stock tank at
his farm in the summer of 1955 regularly and purposefully chased
and bit small juveniles in the same tank. Brecheisen gave me a
juvenile that had been so bitten; the right side of its head was
badly damaged (the eye gone and a portion of the bony orbit
broken) but was partly healed. Ralph J. Donahue told me that he
saw an adult T. ornata attack a juvenal T. carolina, and provided
a photograph of the incident. The juvenile was not injured.

[Pg 648]

Although small box turtles may occasionally be caught and
killed by adults in nature, this seems not to constitute a major
source of predation on the young.

Other animals that may prey upon young box turtles occasionally
(and that were known to occur at the Damm Farm) are bullsnakes
(Pituophis catenifer), red-tailed hawks (Buteo jamaicensis), marsh
hawks (Circus cyaneus), crows (Corvus brachyrhynchos), and
opossums (Didelphis marsupialis), and domestic cats.

Nest predators probably have greater effect on populations of
T. ornata than do predators of hatchlings, juveniles, and adults.
Four robbed nests were found at the Damm Farm; in each instance,
striped skunks were thought to be the predators. E. H. Taylor
told me that he once saw a bullsnake swallow an entire clutch of
newly laid eggs before the female turtle could cover the nest.

Box turtles rely for protection on the closable shell and on inconspicuousness;
defense reactions, except in the rare instances that
biting is provoked, are purely passive.

Box turtles handled in the course of field work varied widely in
their reactions. Many struggled violently when being measured or
marked whereas others were completely passive, closing the shell
tightly and making it difficult for me to examine the soft parts of the
body. These differences in behavior did not seem to be correlated
either with sex or with age; generally lessened activity was associated
with suboptimum body temperatures. All box turtles found in
the field were extremely wary. As soon as one sighted me (sometimes
at a distance of 200 feet or more), it became motionless with
shell raised from the ground and neck extended (Pl. 28, Fig. 5).
Some turtles remained in this motionless stance for half an hour or
more, finally moving slowly away if I remained motionless. Turtles
made no attempt to escape until I approached them closely or until
they were in danger of being trampled by my horse; they would
then move away with remarkable rapidity. Box turtles seemed
unaware of an intruder until he could be seen or until he touched
the turtle. When a turtle was approached from the rear, whistling,
finger snapping, and normal footfalls did not attract its attention.
Latham (1917:16) observed corresponding behavior in T. carolina.
Wever and Vernon (1956) found the ear of T. carolina to be keenly
sensitive to sounds in the range of 100-600 cycles per second but
progressively less sensitive to sounds of higher and lower frequen
[Pg 649]cies.
Surely a predator as stealthy as a coyote could approach a
box turtle unseen and could quickly bite off at least one of the
turtle's legs. Many of the mutilated box turtles that I observed may
have survived such encounters with carnivores. The tendency of
some individuals, when handled, to over-extend the limbs and neck
(rather than closing the shell) in an attempt to escape, would make
them easy victims for any predator.

Ornate box turtles were kept in my home, along with several cats.
Initial behavior was characterized by mutual wariness; subsequently
the cats would follow a turtle about the house for a time, occasionally
pawing at an exposed limb. The turtles withdrew only when
touched or when approached from the front. After a day or two
the cats and turtles ignored each other, often eating and drinking
from the same dishes without incident. Under these circumstances
the cats, I believe, could easily have killed or injured the turtles. A
turtle would occasionally gain the respect of a cat by biting it.

The strong odor sometimes given off by box turtles is produced
by the secretions of four musk glands, two situated anteriorly on
each side and opening by small, nearly invisible apertures beneath
the fourth marginal scute. According to Hoffman (1890:9), two
other musk glands, opening beneath the eighth marginal scute on
each side, are also present in Terrapene; these posterior glands were
not found in the several specimens of T. ornata that I dissected.

Strong odors were produced by nearly all small juveniles until
they became accustomed to being handled. Older juveniles and
adults produced strong odors only in response to pain or injury, as,
for example, when they were killed in the laboratory prior to preservation
or when they were being marked in the field. Young box
turtles were capable of producing strong odors as soon as they
hatched.

Norris and Zweifel (1950:3) considered the odor produced by
T. o. luteola to issue from the "… concentrated, highly pungent
urine…." voided by individuals when they were disturbed, and
thought the production of odor to be a defense mechanism. Neill
(1948b:130) reported that hatchlings of T. carolina with unhealed
umbilical scars emitted a musky odor comparable to that of the
stinkpot, Sternotherus odoratus; he thought the capacity to produce
this odor was lost at about the time that the plastral hinge became
functional.

The function of musk glands in Terrapene and, in all other turtles,
is unknown. Since biting and nuzzling of the edges of the shell is
[Pg 650]
an integral part of the courtship of many turtles, odor produced by
the musk glands may well be a means of social recognition or of
sexual stimulation. Repellant odor may have a protective value in
young box turtles but it is unlikely that larger predators would be
frightened away or even discouraged by odor alone. In this respect
Neill (loc. cit.) and I concur.