  double bar University of Kansas Publications Museum of Natural History Volume 11, No. 10, pp. 527-669, 16 pls., 29 figs. bar March 7, 1960 bar Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz BY JOHN M. LEGLER University of Kansas Lawrence 1960 University of Kansas Publications, Museum of Natural History Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson Volume 11, No. 10, pp. 527-669, 16 pls., 29 figs. Published March 7, 1960 University of Kansas Lawrence, KansasPRINTED IN THE STATE PRINTING PLANT TOPEKA, KANSAS 1960 Union Label 28-773Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz BY John M. Legler CONTENTS INTRODUCTION 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. Acknowledgments 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 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. Systematic Relationships and Distribution 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 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 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. Fossils 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. Economic Importance 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 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). Study Areas 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 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. 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. Materials and Methods 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 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 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. Terminology 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. HABITAT AND LIMITING FACTORS 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 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, 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 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). |
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