Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz Part 1

Natural History of the Ornate Box Turtle, Terrapene ornata ornata Aga.s.siz.

by John M. Legler.

INTRODUCTION

The ornate box turtle, _Terrapene o. ornata_ Aga.s.siz, 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 ma.n.u.script, she has a.s.sisted 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 ma.n.u.script.

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 ma.n.u.script; 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 a.s.sistance 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 relations.h.i.+ps 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 Relations.h.i.+ps 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 sh.e.l.l) 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 p.r.o.nounced 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 Cienegas 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 sh.e.l.l, reduced plastron, and lightly built skull, which completely lacks quadratojugal bones (Fig. 2); most of these specializations seem to be a.s.sociated with adaptation for terrestrial existence in open habitats.

[Ill.u.s.tration: 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 sh.e.l.l (11 to 14 radiations on the second lateral lamina in _luteola_, five to eight in _ornata_). In individuals of _luteola_ the markings of the sh.e.l.l become less distinct with advancing age and eventually are lost; sh.e.l.ls of most old individuals are uniform straw color or pale greenish-brown; this change in coloration does not occur in _T. o. ornata_.

[Ill.u.s.tration: 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 gra.s.sland 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 p.r.i.c.kly Ash (_Xanthoxylum americanum_). The areas used as pasture had thick growths of Buckbush (_Symphoricarpos...o...b..culatus_) mixed with short gra.s.ses (_Bromus j.a.ponicus_, _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 spa.r.s.e 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 oca.s.sional under-cut places in low areas, there were no openings in the rock fences through which box turtles could pa.s.s. 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 gra.s.ses occurred along the top of the hill in the pasture; bluestems (_Andropogon gerardi_, _A. scoparius_) were the dominant species and Switchgra.s.s (_Panic.u.m virgatum_) and Indian gra.s.s (_Sorghastrum nutans_) were scattered throughout. A number of small areas on top of the hill were moderately overgrazed, as indicated by mixture of native gra.s.ses with an a.s.sociation of shorter plants consisting chiefly of Ragweed (_Ambrosia artemisiifolia_ var.

_elatior_), Mugwort (_Artemisia ludoviciana_), j.a.panese Chess (_Bromus j.a.ponicus_), 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 gra.s.ses were spa.r.s.e in this area and gave way to Sideoats Grama (_Bouteloua curtipendula_), extensive patches of Smooth Sumac, and scattered colonies of Buckbrush.

Tall gra.s.ses were dominant on the lower hillsides and small patches of Slough gra.s.s (_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 gra.s.s 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 gra.s.ses 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; gra.s.ses (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 (_Verbasc.u.m Thapsus_), Ragweed, Asters, and a few p.r.i.c.kly 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 Gra.s.s. 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) const.i.tuted 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.