Animal Diversity Web

Geographic Range

Terrapene ornata, commonly referred to as the western box turtle, is an exclusively North American species that primarily occupies southwestern and central United States between the Rocky Mountains and the Mississippi River. This species' northern boundary is marked by Wisconsin and South Dakota. They also range southward into parts of northwestern Mexico.

This species includes two subspecies, Terrapene ornata ornata (ornate box turtle) and Terrapene ornata luteola (desert box turtle). Although they show some overlap in the Great Plains, T. o. luteola predominates along the southwestern boundaries such as Chihuahua and Sonora Mexico, Arizona, and New Mexico. Terrapene ornata ornata is more common in central United States, primarily in Kansas, Nebraska, Oklahoma, and Texas. (Bernstein and Black, 2005; Bowen, et al., 2004; Doroff and Keith, 1990; Nieuwolt-Dacanay, 1997; Packard, et al., 1985)

• Biogeographic Regions
• nearctic
  • native

Habitat

The western box turtle primarily lives in grasslands at altitudes ranging from sea level to 6,500 m, but are typically found around 1,500 m. This species is also commonly found within the burrows of sand dunes. On hot summer days they are often found in small underground burrows called forms, 0.20 to 0.50 m below the surface, averaging 0.35 m deep. During winter hibernation, they are found deeper, at 0.50 to 1.8 m below the surface, depending on ambient temperatures.

Generally, these box turtles are more common in micro-habitats with high ambient temperature, and lower moisture and soil temperatures. Uncommonly, they are also found in ponds and wetlands. Their home ranges generally have a great deal of leaf coverage. Common vegetation surrounding habitat locations include various cacti (Opuntia, Echinocereus), yucca (Yucca glauca), creosote bushes (Larrea divericata), mesquite (Prosopis jusiflora), and various other small shrubs. (Bernstein and Black, 2005; Bernstein, et al., 2007; Converse and Savidge, 2003; Degenhardt and Christiansen, 1974; Doroff and Keith, 1990; Metcalf and Metcalf, 1970; Nieuwolt-Dacanay, 1997; Plummer, 2004)

• Habitat Regions
• temperate
• terrestrial
• freshwater

• Terrestrial Biomes
• desert or dune
• savanna or grassland

• Aquatic Biomes
• lakes and ponds

• Wetlands
• swamp

• Other Habitat Features
• urban
• suburban
• agricultural
• riparian

• Range elevation

  sea level to 6,500 m

  to ft

• Average elevation

  1,500 m

  ft

Physical Description

The bulk of this species' shell, tail, head, and limbs are mostly dark brown or black in color. They have concentric rings on their shells that are indicative of their age, as well as elaborate thick, yellow lines that surround their scutes. All adults have yellow spots on their heads, but subspecies T. o. luteola has more yellow stripes on their shells and body than T. o. ornata. Additionally, sexual dichromatism exists in this species. Bright red eyes and green heads are characteristic of males, with brighter colors perhaps improving reproductive success. A female's eyes and head are typically brown or black.

On average, adults weigh between 198 to 538 g. The carapace averages 120 mm in length for adults. Although still roughly dome-shaped, western box turtles are known for having relatively convex carapaces. The plastron averages 120 mm long for females and 116 mm long for males. Differences in the average shell size between females and males is generally contributed to the fact that females tend to be slightly larger than males.

T. ornata prefer temperature ranges from 25 to 30°C year round. Typically their metabolic rates are between 0.05 to 0.30 ml/h, with averages at 0.158 ml/h. (Bernstein and Black, 2005; Blair, 1976; Costanzo, 1982; Gatten, Jr., 1974; Metcalf and Metcalf, 1985; Miller and Birchard, 2005; Packard, et al., 1985; St. Clair, 1998)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger
• male more colorful

• Range mass

  198 to 538 g

  6.98 to 18.96 oz

• Average mass

  398 g

  14.03 oz

• Range length

  95 to 150 mm

  3.74 to 5.91 in

• Average length

  120 mm

  4.72 in

• Range basal metabolic rate

  0.05 to 0.30 cm3.O2/g/hr

• Average basal metabolic rate

  0.158 cm3.O2/g/hr

Development

The eggs of the western box turtle are relatively large compared to other species in the Family Emydidae. Egg width is directly related to pelvic width of the female, but not her overall body size. Incubation time for eggs is temperature-dependent. They are normally incubated for about 50 days, although incubation period ranges have not yet been published. It is known, however, that turtles incubated at temperatures above the typical 20 to 30°C often develop faster. The moisture at which the eggs are incubated has a significant effect on the hatchlings. Wet substrates produce turtles with increased masses from the time of egg-laying, whereas eggs incubated on dry substrates decrease their mass. Wet substrates also produce hatchlings with longer carapaces as compared to drier substrates. Sex ratios at hatching may be determined by the environmental temperature surrounding the eggs. At temperatures at or above 29°C, hatchlings are generally females, and below 28°C, they tend to be male.

Many hatchlings do not reach sexual maturity due to poor parental care and predation. Growth rates for juveniles are dependent upon wet seasons and the abundance of food and water. Western box turtles are well-developed at the time of birth and undergo steady development over time, although growth rates have not been published. Because the plastron, which is the ventral portion of the shell, is important for protection, plastron size increases faster than the body mass of the turtles. Adult females grow to about 120 mm and males grow to about 116 mm in plastron length with plastron widths averaging between 60 to 80 mm. Terrapene ornata reach their maximum size around age thirteen. (Blair, 1976; Doroff and Keith, 1990; Metcalf and Metcalf, 1970; Metcalf and Metcalf, 1985; Miller and Birchard, 2005; Nieuwolt-Dacanay, 1997; Packard, et al., 1985)

• Development - Life Cycle
• temperature sex determination
• indeterminate growth

Reproduction

This species mates during the majority of its active season, between the months of April and October. Males and females may mate with several members of the opposite sex in one mating season. However, through the practice of sperm storage, in which a female turtle may mate with several males and hold their sperm for an extended period of time, only one or two clutches are generally laid per year.

Males usually pursue females. Their courtship behavior generally consists of staring in the direction of the female, following her around, and rubbing up against her. Male physical contact can include nudging the lower end of the female's carapace, bumping shells, and positioning himself on top of the female with his forelimbs. The female, on the other hand, often runs from the male, leaving him behind to fight other males and chase after her. Chasing after the female lasts about half an hour, and eventually the female will mate with the winning male.

Once the male positions himself on top of the female he may squirt fluid from his nostrils across the length of her carapace, often multiple times. This is thought to be from bumping of their shells against each other, which causes the water from the male's stomach to be forced out of his nostrils. During copulation, the male grasps the female with all four forelimbs. The front two forelimbs grasp the female much more loosely to allow him to be in an erect position, while the back forelimbs are used to lift his body and bump against the female's shell. (Blair, 1976; Brumwell, 1940; Taylor, 1933)

• Mating System
• polygynandrous (promiscuous)

Western box turtles begin their mating season in late April and end in late July. However, their mating season is often postponed during dry years and ova may even be re-absorbed in extremely dry seasons when food supply is insufficient. The females are generally about 8 years old and have a carapace length of 100 mm or greater at sexual maturity. Males reach sexual maturity at 5 years of age, with a carapace length of 100 mm or less. For this reason, it is not uncommon to see a smaller male attempting to mate with a larger female.

Courtship and mating begin in the early spring and continue throughout the summer. After being fertilized, eggs are not released from the female for about 50 days. Nesting occurs mostly in July and eggs are laid by the end of July. Nests are usually built in sandy soil, 10 cm underneath rocks or vegetation. Females lay their eggs two hours after sunrise or two hours before sunset. Parental care is nonexistent beyond the nesting effort. Not surprisingly, hatchling mortality is common.

These turtles generally have only one or two clutches per mating season, bearing 1 to 8 eggs. Each of these eggs weighs approximately 10 grams. Terrapene ornata luteola clutch size is smaller than T. ornata ornata, due to their increased egg width compared to T. o. ornata. Terrapene o. ornata have clutch averages of 4.7 eggs, about 2.17 cm wide. On the other hand, T. o. luteola have average clutch sizes of 2.7 eggs, about 2.6 cm wide. If a female bears a large clutch one season, she may not reproduce the following year.

Western box turtles may store several males' sperm at once internally. Although sperm storage does not have any direct effect on the female, it allows her to re-use the same sperm or hold the sperm over an extended period of time. This benefits the western box turtle population because it allows them to reproduce during preferred environmental factors. (Avise and Pearse, 2001; Blair, 1976; Doroff and Keith, 1990; Nieuwolt-Dacanay, 1997; Packard, et al., 1985)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• oviparous
• sperm-storing
• delayed fertilization

• Breeding interval

  Western box turtles generally breed once or twice during the summer.

• Breeding season

  Breeding occurs between April and July.

• Range number of offspring

  1 to 8

• Average number of offspring

  3

• Average gestation period

  50 days

• Average age at sexual or reproductive maturity (female)

  8 years

• Average age at sexual or reproductive maturity (male)

  5 years

Like most turtles, western box turtles are independent at hatching and receive no parental care from either parent. Males do not appear to have any role in reproduction after copulation. Females provide provisioning during the early stages of development, long enough to ensure that the offspring have sufficient egg yolk nutrition. They also lay the eggs in nests, often under rocks or vegetation, providing some protection. After that point, the eggs are left to incubate and develop on their own. (Nieuwolt-Dacanay, 1997)

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Western box turtles are known to live between 30 to 37 years in the wild, with most living for about 32 years. The oldest known wild western box turtle was over 40 years old. The maximum longevity of this species in captivity averages 28.4 years, but may vary drastically depending on the way they are caught and handled. If T. ornata is taken from the wild and suddenly subjected to a captive lifestyle, it will die very quickly. However, if it is adequately adjusted to a captive lifestyle or captive from birth, it may live a more normal lifespan. (Blair, 1976; Converse, et al., 2005)

• Average lifespan
  Status: wild

  40 years

• Range lifespan
  Status: captivity

  28.4 (high) years

• Typical lifespan
  Status: wild

  30 to 37 years

• Average lifespan
  Status: wild

  32 years

Behavior

Western box turtles are mobile, terrestrial turtles. Most of their lives, however, are actually spent underground in burrows to escape temperature extremes in an attempt to maintain thermal stability. Ideal body temperatures for this species lie between 21 to 25°C. Because western box turtles are one of the only terrestrial turtle species, they do not have water to rely on as an effective way to reduce their body temperatures; therefore, they cannot withstand extreme temperatures. Instead, they retreat underground and hibernate during the winter. Even throughout their active seasons, much of their time is spent inside of daily forms that they create. Forms are typically dug at a 30 to 40 degree angle to the soil, along the bank of a ditch or near vegetative coverage. Deeper forms and burrows are made depending on how cold it gets. The time the turtle may spend in these forms is based upon ambient temperature and rain. During summer rain showers this species may emerge from the ground to find food. They arise to seek areas of sunlight to raise their body temperatures, as well as to dry out their body parts and rid themselves of parasites as an adaptive technique. Social behavior is negligible in this species, as they tend to interact only during reproductive efforts. (Bernstein and Black, 2005; Bernstein, et al., 2007; Blair, 1976; Converse and Savidge, 2003; Converse, et al., 2005; Degenhardt and Christiansen, 1974; Doroff and Keith, 1990; Gatten, Jr., 1974; Metcalf and Metcalf, 1970; Metcalf and Metcalf, 1979; Nieuwolt, 1996; Nieuwolt-Dacanay, 1997; Packard, et al., 1985; Plummer, 2004)

• Key Behaviors
• terricolous
• fossorial
• crepuscular
• motile
• sedentary
• hibernation
• daily torpor

• Range territory size

  0.002 to 0.581 km^2

• Average territory size

  0.05 km^2

Home Range

Western box turtles generally stay within restricted perimeters. They tend to hibernate in the same sand dunes year after year, or at least within 1 meter of the previous year's hibernation cavities. Several western box turtles may overlap in their home ranges at any given time. A study by Nieuwolt described their home ranges as "roughly elliptical," but these were influenced heavily by the presence of roads. Adults occupy about 0.054 hectares, while juveniles have much smaller home ranges of about 0.015 hectares. Because there is no social hierarchy seen in this species, male and females occupy home ranges of the same size. Home range size largely depends on the availability of food. Areas with an abundance of food consist of higher population densities within smaller home ranges. Further, because T. ornata luteola live in drier areas with a reduced food supply, they tend to occupy larger home ranges than T. ornata ornata. The home range for T. ornata ornata averages 94 to 267 m, while those of T. ornata luteola are 32 to 526 m in diameter. (Bernstein, et al., 2007; Doroff and Keith, 1990; Metcalf and Metcalf, 1979; Nieuwolt, 1996)

Communication and Perception

Little is known about the communication and perception of the western box turtle. They spend minimal time in social interactions with one another, likely because most of their time is spent underground in burrows. Typically they are only seen interacting with one another during mating season. Males can be aggressive and can often be found biting or bumping shells with one another, but this aggression only seems to occur exclusively between two males.

Western box turtles return to the same forms and hibernation locations year after year. They are also able to distinguish certain smells and will continuously choose particular foods over others. Their sense of smell can also allow them to sense nearby predators. This species is able to sense moving versus stationary insects that they eat, although it is unclear whether their sense of motion is due to their vision or hearing. In visual experiments, this species chooses red-colored food over all others, even when the food is not associated with a particular smell. (Fitch, 1965; Metcalf and Metcalf, 1970; Nieuwolt, 1996)

• Communication Channels
• visual
• tactile

• Perception Channels
• visual
• tactile
• chemical

Food Habits

Terrapene ornata is an omnivore, and changes eating habits based upon availability of food. Young western box turtles tend to eat a greater percentage of insects than adults. The most common foods that western box turtles feed on include earthworms, grasshoppers, beetles, slugs, fruits, and plants. Plants and fruits are generally eaten half as often as animal food types. Of the available plants, the most commonly consumed are mulberries (Morus alba), dandelion (Taraxacum) flowers, and prickly pear cacti (Opuntia humifusa). They have also been recorded feeding on small fish, carrion, and feces.

In captivity, it is vital that this species still receives foods with sufficient calcium supplies, as calcium is critical to their survival. (Costanzo, 1982; Doroff and Keith, 1990; Metcalf and Metcalf, 1970; Nieuwolt-Dacanay, 1997; Stone and Moll, 2006)

• Primary Diet
• omnivore

• Animal Foods
• fish
• eggs
• body fluids
• carrion
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms
• other marine invertebrates

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit
• flowers

• Other Foods
• dung

Predation

Due to their small size and reduced mobility, this species has many known predators. Because western box turtles spend the majority of their lives inactive in underground burrows, they are easily targeted by predators. Common predators include coyotes (Canis latrans), striped skunks (Mephitis mephitis), white necked ravens (Corvus cryptoleucus), crows (Corvus brachyrhynchos), copperheads (Agkistrodon contortrix), raccoons (Procyon lotor), Virginia opossums (Didelphis virginiana), American minks (Neovison vison), red foxes (Vulpes vulpes), and dogs (Canis lupus familiaris).

Over time, western box turtles have developed harder and thicker shells for protection. Box turtles, in general, also have the ability to tighten their shells around their body, and retract their head and forelimbs underneath the shell to minimize injury. Active defense mechanisms by western box turtles include fighting back or distancing themselves from the predator. More commonly, however, this species responds to predation passively, which is referred to as their “freeze” response. They withdraw their body parts into their shells and remain still. They may also bury themselves in burrows or retreat into water.

Despite these defenses, live individuals are often found with many scars indicative of predation. This includes missing outer layers of their skin and cracks in their shells. Juveniles and young western box turtles experience high mortality due to predation. Therefore, the most sufficient adaptation to predators is to move as far away from edge habitats as possible, where there are not as many predators available for attack. (Doroff and Keith, 1990; Metcalf and Metcalf, 1970; Miller and Birchard, 2005; Temple, 1987; Wren, et al., 1998; Doroff and Keith, 1990; Metcalf and Metcalf, 1970; Miller and Birchard, 2005; Temple, 1987; Wren, et al., 1998)

• Known Predators

  • coyotes, Canis latrans
  • striped skunks, Mephitis mephitis
  • white necked ravens, Corvus cryptoleucus
  • American crows, Corvus brachyrhynchos
  • copperheads, Agkistrodon contortrix
  • raccoons, Procyon lotor
  • Virginia opossums, Didelphis virginiana
  • minks, Neovison vison
  • red foxs, Vulpes vulpes
  • dogs, Canis lupus familiaris

Ecosystem Roles

Because all turtles lay their eggs on land and they are often left unattended, turtle eggs and juveniles are commonly preyed upon. Terrapene ornata also serve as prey for dogs (Canis familiaris), coyotes (Canis latrans), and many other animal species. Western box turtles also serve as host species for the cheyletoid mites Harpyrhynchus novoplumaris and Harpyrhychus brevis, as well as the roundworm, Oxysomatium variabilis.

This species can also be useful as seed dispersers, because they eat various seeds and randomly distribute them through their feces. They also feed on carrion, contributing to biodegradation. (Harwood, 1930; Moss, et al., 1968; Stone and Moll, 2009; Temple, 1987)

• Ecosystem Impact
• disperses seeds
• biodegradation

Economic Importance for Humans: Positive

Western box turtles are economically important as a source of pet trade for humans, particularly in Florida and California.

These turtles are a potential source of ecotourism in Kansas, where T. ornata is recognized as the state reptile. At the Kansas Wetlands Educational Center, tourists can learn about the conservation and history of this species. (Bowen, et al., 2004; Collins and Collins, 2006)

• Positive Impacts
• pet trade
• ecotourism
• research and education

Economic Importance for Humans: Negative

This species has been known to bite humans when they feel threatened. There is no information that indicates spread of human disease by western box turtles, though it is important to note that about 14 percent of the 70,000 cases of human Salmonella have been linked to contact with turtles, in general. (Richards, et al., 2004; Wren, et al., 1998)

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

The western box turtle population is considered threatened according to both the IUCN Red List and Appendix II of CITES.

Automobiles are one of the leading causes of T. ornata deaths due to their home range overlap with highways. Due to the loyalty of T. ornata to its home range, loss of prairie habitats in the development of houses and croplands also contributes substantially to the decline of this species. Because this species spends the majority of their lives inactive in underground burrows, they are also easily preyed upon. To a lesser extent, fatalities caused by human activity can also be attributed to farming machinery and lawn mowers. Slow maturity to reproductive age and high mortality of juveniles may also jeopardize the recovery of the western box turtle population.

Terrapene ornata is protected under several state laws in the U.S. However, this species is still subjected to pet trade in other states that have not yet made it illegal, which makes it difficult for this population to recover from its rapid decline. Educating the public about the decline of this species and how human activity contributes to this decline may keep this population from going extinct. (Bernstein, et al., 2007; Bowen, et al., 2004; Converse and Savidge, 2003; Doroff and Keith, 1990)

• IUCN Red List

  Near Threatened

• US Federal List

  No special status

• CITES

  Appendix II

• State of Michigan List

  No special status

Contributors

Lyndsay Coker (author), Radford University, Karen Powers (editor), Radford University, Angela Miner (editor), Animal Diversity Web Staff.

References

Avise, J., D. Pearse. 2001. Turtle mating systems: behavior, sperm storage, and genetic paternity. Journal of Heredity, 92/2: 206-211.

Bernstein, N., R. Black. 2005. Thermal environment of overwintering ornate box turtles, Terrapene ornata ornata, in Iowa. The American Midland Naturalist, 153/2: 370-377.

Bernstein, N., R. Richtsmeier, R. Black, B. Montgomery. 2007. Home range and philopatry in the ornate box turtle, Terrapene ornata ornata, in Iowa. American Midland Naturalist, 157/1: 162-174.

Blair, W. 1976. Some aspects of the biology of the ornate box turtle, Terrapene ornata. The Southwestern Naturalist, 21/1: 89-103.

Bowen, K., P. Colbert, F. Janzen. 2004. Survival and recruitment in a human-impacted population of ornate box turtles, Terrapene ornata, with recommendations for conservation and management. Journal of Herpetology, 38/4: 562-568.

Brumwell, M. 1940. Notes on the courtship of the turtle, Terrapene ornata. Transactions of the Kansas Academy of Science, 43/1: 391-392.

Collins, J., S. Collins. 2006. The amphibians, turtles, and reptiles of Cheyenne Bottoms.. Fort Hays State University: Sternberg Museum of Natural History.

Converse, S., J. Iverson, J. Savidge. 2005. Demographics of an ornate box turtle population experiencing minimal human-induced disturbances. Ecological Applications, 15/6: 2171-2179.

Converse, S., J. Savidge. 2003. Ambient temperature, activity, and microhabitat use by ornate box turtles (Terrapene ornata ornata). Journal of Herpetology, 37/4: 665-670.

Costanzo, J. 1982. Heating and cooling rates of Terrapene ornata and Chrysemys picta in water. Bios, 53/3: 159-166.

Degenhardt, W., J. Christiansen. 1974. Distribution and habitats of turtles in New Mexico. The Southwestern Naturalist, 19/1: 21-46.

Doroff, A., L. Keith. 1990. Demography and ecology of an ornate box turtle (Terrapene ornata) population in south-central Wisconsin. Copeia, 1990/2: 387-399.

Fitch, A. 1965. Sensory cues in the feeding of the ornate box turtle. Transactions of the Kansas Academy of Science, 68/4: 522-532.

Gatten, Jr., R. 1974. Effect of nutritional status on the preferred body temperature of the turtles Trachemys scripta and Terrapene ornata. Copeia, 1974/4: 912-917.

Harwood, P. 1930. A new species of Oxysomatium (Nematoda) with some remarks on the genera Oxysomatium and Aplectena, and observations on the life history. The Journal of Parasitology, 17/2: 61-73.

Metcalf, A., E. Metcalf. 1985. Longevity in some ornate box turtles (Terrapene ornata ornata). Journal of Herpetology, 19/1: 157-158.

Metcalf, E., A. Metcalf. 1979. Mortality in hibernating ornate box turtles, Terrapene ornata. Herpetologica, 35/1: 93-96.

Metcalf, E., A. Metcalf. 1970. Observations on ornate box turtles (Terrapene ornata ornata Agassiz). Transactions of the Kansas Academy of Science, 73/1: 96-117.

Miller, K., G. Birchard. 2005. Influence of body size on shell mass in the ornate box turtle, Terrapene ornata. Journal of Herpetology, 39/1: 158-161.

Moss, W., J. Oliver, B. Nelson. 1968. Karotypes and developmental stages of Harpyrynchus novoplumaris sp. n. (Acari: Cheyletoidea: Harpyrhynchidae), a parasite of North American birds. The American Society of Parasitologists, 54/2: 377-392.

Nieuwolt-Dacanay, P. 1997. Reproduction in the western box turtle, Terrapene ornata luteola. Copeia, 1997/4: 819-826.

Nieuwolt, P. 1996. Movement, activity, and microhabitat selection in the western box turtle, Terrapene ornata luteola, in New Mexico. Herpetologica, 52/4: 487-495.

Packard, G., M. Packard, W. Gutzke. 1985. Influence of hydration of the environment on eggs and embryos of the terrestrial turtle Terrapene ornata. Physiological Zoology, 58/5: 564-575.

Plummer, M. 2004. Seasonal inactivity of the desert box turtle, Terrapene ornata luteola, at the species' southwestern range limit in Arizona. Journal of Herpetology, 38/4: 589-593.

Richards, J., J. Brown, T. Kelly, A. Fountain, J. Sleeman. 2004. Absence of detectable Salmonella cloacal shedding in free-living reptiles on admission to the wildlife center of Virginia. Journal of Zoo and Wildlife Medicine, 35/4: 562-563.

Shine, R., J. Iverson. 1995. Patterns of survival, growth and maturation in turtles. Oikos, 72/3: 343-348.

Smith, N., M. De Carvalho. 1985. Heart rate response to threat and diving in the ornate box turtle, Terrapene ornata. The University of Chicago Press, 58/2: 236-241.

St. Clair, R. 1998. Patterns of growth and sexual size dimorphism in two species of box turtles with environmental sex determination. Oecologia, 115/4: 501-507.

Stone, M., D. Moll. 2009. Abundance and diversity of seeds in the digestive tracts of Terrapene carolina and T. ornata in southwestern Missouri. The Southwestern Naturalist, 54/3: 346-350.

Stone, M., D. Moll. 2006. Diet-dependent differences in digestive efficiency in two sympatric species of box turtles, Terrapene carolina and Terrapene ornata. Journal of Herpetology, 40/3: 364-371.

Taylor, E. 1933. Observations on the courtship of turtles. University of Kansas Science Bulletin, 21/1: 269-271.

Temple, S. 1987. Predation on turtle nests increases near ecological edges. Copeia, 1987/1: 250-252.

Voigt, W. 1975. Heating and cooling rates and their effects upon heart rate and subcutaneous temperatures in the desert tortoise, Gopherus agassizii. Comparitive Biochemistry Physiology, 52/1: 527-531.

Wren, K., D. Claussen, M. Kurz. 1998. The effects of body size and extrinsic mass on the locomotion of the ornate box turtle, Terrapene ornata. Journal of Herpetology, 32/1: 144-150.

Zani, P., R. Kram. 2008. Low metabolic cost of locomotion in ornate box turtles, Terrapene ornata. The Journal of Experimental Biology, 211/1: 3671-3676.