Read Ebook: Natural History of the Ornate Box Turtle Terrapene ornata ornata Agassiz by Legler John M

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Introduction 531 Acknowledgments 531 Systematic Relationships and Distribution 532 Fossils 534 Economic Importance 534 Study Areas 535 Materials and Methods 537 Terminology 539

Habitat and Limiting Factors 539

Habitat in Kansas 542

Reproduction 543

Mating 543 Insemination 545 Sexual Cycle of Males 545 Sexual Cycle of Females 549 Nesting 554 Eggs 558 Embryonic Development 560 Fertility and Prenatal Mortality 564 Reproductive Potential 565 Number of Reproductive Years 565

Growth and Development 565 Initiation of Growth 565 Size and Appearance at Hatching 566 Growth of Epidermal Laminae 568 Growth of Juveniles 575 Growth in Later Life 578 Annual Period of Growth 580 Environmental Factors Influencing Growth 580 Number of Growing Years 584 Longevity 585 Weight 586 Bony Shell 586 Color and Markings 593 Wear 595

Sexual Dimorphism 595

Temperature Relationships 598 Optimum Temperature 599 Basking 600 Toleration of Thermal Maxima and Minima 601

Hibernation 611

Diet 617

Populations 623

Movements 626 Locomotion 627 Daily Cycle of Activity 629 Seasonal Cycle of Activity 630 Home Range 632 Homing Behavior 636 Social Relationships 637

Injuries 638

Repair of Injuries to the Shell 641

Ectoparasites 643

Predators 646

Defence 648

Discussion of Adaptations 650

Summary 656

Literature cited 663

INTRODUCTION

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 , Dr. George W. Byers , and Dr. Sydney Anderson .

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 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 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 , from the Graduate School, University of Kansas, for which I thank Dean John H. Nelson.

Systematic Relationships and Distribution

Fossils

Economic Importance

Study Areas

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 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 , Elms , Cottonwood , and Northern Prickly Ash . The areas used as pasture had thick growths of Buckbush mixed with short grasses . 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 upon which beef-cattle were grazed . Rock fences 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 , Red Mulberry , Osage Orange , Black Cherry , Box-Elder , and Dogwood --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 . 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 .

Rich stands of prairie grasses occurred along the top of the hill in the pasture; bluestems were the dominant species and Switchgrass and Indian grass 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 , Mugwort , Japanese Chess , and Asters .

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 , extensive patches of Smooth Sumac, and scattered colonies of Buckbrush.

Tall grasses were dominant on the lower hillsides and small patches of Slough grass 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 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 . 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 were absent and dominant vegetation consisted of Buffalo-bur , Blue Vervain , Mullein , Ragweed, Asters, and a few Prickly Pear . 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 and that in the southwestern part of the pasture 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 . 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 and Leopard frogs .

The three parts of the pasture in which studies were concentrated were designated as separate subdivisions. The northwest corner area was triangular and bounded on two sides by rock fences and on its third side by a deep ravine. The southern ravine area constituted the part of the lower southern hillside drained by a series of ravines. The house pond area 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.

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 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 . 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 and later modified by Stickel --a tin can, cut to fit the shell of a turtle, with an axle that bore a spool of thread . 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 , 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 . 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 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 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.

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