Box turtle

“ Box turtles probably benefit man by destroying large numbers of crop-damaging insects (locustids and noctuid caterpillars) .
Box turtles were more numerous than most kinds of reptiles at the Damm Farm and were the most conspicuous of any kind of reptile. One hundred and ninety-four turtles were marked; one-fourth of these were recaptured at least twice. Population density in certain areas of favorable habitat ranged from 2.6 to 6.3 turtles per acre. The total number of individuals on the study area was estimated to be 286. ”

“ 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 walk with the shell held off the substrate. They are able to climb steep embankments or low barriers with [Pg 662] some facility. Swimming ability is sufficient to permit survival in water and traversal of water-barriers but ornate box turtles almost never swim voluntarily.
Daily activity consists of periods of basking, foraging, and rest, the durations of which are influenced by temperature and humidity. There is no activity after dark except that of nesting females. ”

“ 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. ”

“ 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] ”

“ 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. ”

“ 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. ”

“ Ornate box turtles are able to detect the presence of intruders, by sight, from a distance of several hundred feet in open country; apparently, intruders are not detected until seen. Defensive behavior is passive; the shell is closed tightly in response to painful stimuli and, in some instances, at the sight of an intruder. Juveniles usually void odoriferous fluid from the musk glands when handled but adults do so only in response to pain or injury. ”

“ 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. ”

“ It seems remarkable that none of the species of true tortoises occurring in the grasslands of the world has developed insectivorous habits or utilized the unique food niche (in regard to dung-foraging) filled by ornate box turtles in the Great Plains; tortoises are, as far as is known, strictly herbivorous. The ranges of Gopherus and Terrapene are now almost mutually exclusive and the two kinds do not compete with each other for food in the few places where they occur together. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ The closable shell of box turtles is of obvious survival value in providing protection for the soft parts of the body. In most of the species of Terrapene, the lobes of the plastron completely close the openings of the shell; closure is so tightly effected in some individuals that it is difficult to insert the blade of a knife between the adpressed margins of carapace and plastron. In T. ornata nevertheless, both lobes of the plastron are deficient on their lateral margins; four narrow openings remain when the lobes are drawn shut. ”

“ 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. ”

“ 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. ”

“ The box tortoise can retire into its shell and close the under part into a groove of the upper edge, and thus form for itself an impregnable retreat; but there are varieties only partly encased by the shell, which cannot bring their heads and feet under cover.
The turtle wanders about with its house on its back as the snail does, and against its enemies it can close its doors and be emphatically “not at home.” Turtles have keen sight and hearing; they have no teeth, the jaws being simply cased in horn, like those of birds. Many of them are capable of making loud sounds. ”

“ 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. ”

“ 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 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ Retention of epidermal laminae (as opposed to regular exfoliation of the older parts of scutes) occurs in all box turtles, in several other groups of terrestrial emyids, and in testudinids. The phenomenon is here considered to be a specialization of scute shedding—developed in terrestrial and semiterrestrial chelonians—that provides additional protection to the shell against wear and minor injuries. ”

“ 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. ”