Wood Turtles had a more southerly distribution during the Late Pleistocene ("ice age"), with fossils being described from Tennessee and Georgia (Ernst, Lovich, and Barbour, 1994).
The oldest fossil Wood Turtle appears to be a nearly complete shell of an adult male specimen found in late Hemphillian deposits (late Miocene epoch) in Nebraska. This fossil, which is approximately 6 million year old, will be described by its discoverer, Mr. Shane Tucker, and Dr. Michael Voorhies of the University of Nebraska (Voorhies, pers. comm., June 2000).
The relationships of the Wood Turtle to its relatives in the subfamily emydinae (in the genera Clemmys, Emys, Emydoidea, and Terrapene) have been recently studied; the genus Clemmys, as long suspected, was found to be paraphyletic (Bickham et al., 1996; Burke et al., 1996; Feldman and Parham, 2001). According to the latest published revisions, the Wood Turtle will now be combined with its closest relative, the Bog turtle (Clemmys muhlenbergii), in the genus Glyptemys; the correct scientific names for these turtles are now Glyptemys insculpta and Glyptemys muhlenbergii, respectively, although it will predictably take some time before the new combinations are universally used and recognized. The Spotted Turtle, Clemmys guttata, is the only species remaining in the genus Clemmys (Holman and Fritz, 2001; Feldman and Parham, 2002).
Hybrids between the Wood Turtle and the Blanding's turtle, Emydoidea blandingii, have recently been described (Harding, 1999).
Adult wood turtles have a carapace length of 16 to 25 cm (6.3 to 9.8 inches). The brownish to gray-brown carapace has a low central keel, and the scutes usually show well-defined concentric growth annuli, giving the shell a rough, "sculptured" appearance that probably gave the species its specific name (and perhaps its common name as well). In some specimens, the accumulated annuli may give each carapace scute a somewhat flattened pyramidal shape (though this character has been over-emphasized in some earlier literature). The carapaces of older specimens may be worn quite smooth. The vertebral scutes sometimes display radiating yellow streaks, or yellow pigment may be restricted to the keel. The hingeless plastron is yellow with a black blotch at the rear outer corner of each scute; there is a V-shaped notch at the tail. Plastral scutes display prominent annuli, though, as with the carapace, these can be worn smooth over time.
(Note: Counting the scute annuli, or "growth rings," can offer a reasonable estimate of age in a juvenile animal, but this method becomes increasingly unreliable as the specimen approaches and then attains maturity. In older animals, growth, and thus the formation of annuli, may essentially cease; however, counting scute annuli will usually provide a reliable minimum age for a specimen.)
The head of the Wood Turtle is black, occasionally with light dots or other markings; the scales on the upper legs are black to mottled brown, while the skin on the throat, lower neck, and on the lower surfaces of the legs can be yellow, orange, or orange-red to salmon-red, sometimes speckled with darker pigment. This skin color varies between localities, and shows some regional variation, with yellow to yellow-orange predominating in the western (Great Lakes) part of the range, and orange to reddish skin color characterizing eastern specimens (Harding, 1997).
Hatchling Wood Turtles have nearly circular carapaces that range in length from 2.8 to 3.8 cm (1.1 to 1.5 inches); their tails are nearly as long as the carapace. At hatching they are a uniform brown or gray color dorsally; the brighter juvenile and adult coloration described above is attained during the first full year of growth (Harding, 1997).
Compared to females, adult male G. insculpta tend to have wider heads and higher, more elongate and domed, carapaces; the plastron is concave (depressed) in the center, and their tails are thicker and longer, with the vent (cloacal opening) beyond the edge of the carapace when the tail is extended. Compared to males, adult females tend to have lower and wider, more flaring carapaces; the plastron is flat to slightly convex, the tail is narrower and slightly shorter, with the vent situated beneath the edge of the carapace when the tail is extended (Ernst, Lovich, and Barbour, 1994; Harding, 1997).
Other Physical Features: ectothermic ; bilateral symmetry
Range lifespan
Status: captivity: 58 (high) hours.
Average lifespan
Status: captivity: 12.5 years.
Average lifespan
Status: captivity: 60.0 years.
Glyptemys insculpta is almost invariably found in association with moving water (streams, creeks, or rivers), although individuals in some populations may wander considerable distances away from water, especially in the warmer months. Females may be more terrestrial than males in some populations. Streams with sand or sand and gravel bottoms are preferred, but rocky stream courses are sometimes used, especially in the north-eastern portion of the range. Wood turtles are often described as a woodland species, but in some places they appear to thrive in a mosaic habitat of riparian woods, shrub or berry thickets, swamps, and open, grassy areas. Some unvegetated or sparsely vegetated patches, preferably with moist, but not saturated, sand substrate, are needed for nesting (Harding, 1991; Ernst, Lovich, and Barbour, 1994; Harding, 1997; Tuttle, 1996).
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: rivers and streams
Glyptemys insculpta occurs in a relatively small area of eastern Canada and the northeastern United States, from Nova Scotia and New Brunswick south through New England, Pennsylvania and northern New Jersey, to northern Virginia, and west through southern Quebec, southern Ontario, northern Michigan (northern Lower and Upper Peninsulas), northern and central Wisconsin, to eastern Minnesota; an isolated population occurs in northeastern Iowa. Within this range, this turtle is generally uncommon to rare and spottily distributed (Harding, 1997; Conant and Collins, 1998).
Biogeographic Regions: nearctic (Native )
Glyptemys insculpta is an omnivorous species that can feed both in or out of water. Natural foods reported for the species include leaves and flowers of various herbaceous and woody plants (violet, strawberry, raspberry, willow), fruits (berries), fungi, slugs, snails, worms, and insects. They are usually slow, deliberate feeders, and seem incapable of capturing fish or other fast-moving prey, though they will opportunistically consume young mice or eggs, or scavenge dead animals (Ernst, Lovich, and Barbour, 1994; Harding, 1997)
Wood Turtles in some populations are known to capture earthworms by thumping the ground with their forefeet or the front of the plastron. It is thought that the worms may mistake the vibrations caused by this thumping for the approach of a mole or perhaps the advent of a hard rain, and thus come to the surface, only to be grabbed by the hungry turtle (Harding and Bloomer, 1979; Kaufmann, et al., 1989; Ernst, Lovich, and Barbour, 1994).
Animal Foods: eggs; carrion ; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic crustaceans
Plant Foods: leaves; roots and tubers; fruit; flowers
Other Foods: fungus
Primary Diet: omnivore
Wood Turtles were once harvested extensively for human food (in the east) and for the biological supply trade (especially in the western Great Lakes area), and in the last few decades they have been mercilessly exploited for the pet trade range-wide. None of these activities are sustainable in the long-term; most populations of Wood Turtles are now greatly reduced from former numbers, and many have been totally extirpated (Harding, 1991, 1997).
Positive Impacts: pet trade ; food ; body parts are source of valuable material; research and education
This species is harmless to human interests and values.
Glyptemys insculpta displays a number of life history traits that make it especially vulnerable to exploitation and habitat alteration by humans. In this and many other turtle and tortoise species, low reproductive rates (low clutch size and/or high nest and hatchling mortality) and delayed sexual maturity are normally balanced by relatively high survivorship of older juveniles and adults, and a long adult reproductive lifespan. It has been demonstrated that such species have virtually no harvestable surplus in their populations (assuming the desirability of population stability), and any factor (natural or human-caused) which reduces the normally high survivorship of older juveniles and mature adults will result in a declining or even extirpated population. In addition, these turtle populations will predictably be very slow in recovering from any factor which significantly reduces numbers of mature individuals. The Wood Turtle may be equally, or even more vulnerable than certain other well-studied turtle species (such as Emydoidea blandingii) in this regard (Congdon et al., 1993; Harding, 1991, and unpubl. data).
Direct removal by humans is the primary threat to the species in some portions of the Wood Turtle's range. Removal can take the form of road mortality, shooting of basking turtles by vandals, commercial poaching for the pet trade, or just incidental collection by stream-based recreationists such as canoeists and fishermen. In one study (Garber and Burger, 1995), a previously unexploited population of Wood Turtles declined to virtual extirpation within a decade of being exposed to human recreationists. Glyptemys insculpta is legally protected from commercial collecting practically range-wide at present, and collection for personal use is at least regulated, if not prohibited, by most of the states and provinces where it occurs.
Wood Turtles have also suffered greatly from habitat loss and degradation. While the species seems somewhat tolerant of modest timber harvest and agricultural activity in its habitat, intensive forestry, farming, or industrial or residential development in the riparian zone can severely impact Wood Turtles. Intensive, mechanized agriculture can result in maiming and deaths of Wood Turtles due to impacts from farm machinery (Saumure and Bider, 1998). Certain fish management practices that involve removal ("stabilization") of sand bank nesting sites along northern rivers is a relatively recent threat that can reduce reproductive opportunities for this and other turtle species. An additional threat is the recent increase in numbers of "human-subsidized" predators, particularly raccoons (Procyon lotor), which not only destroy turtle eggs and hatchlings, but can also kill or maim adult turtles (Harding, 1985; 1991, 1997, pers.obs.).
The long-term future for this species is bleak unless its riparian habitats are protected and the animals themselves are left undisturbed. Wood turtles are listed as vulnerable by the IUCN and special concern in the state of Michigan, and they are in CITES appendix II.
US Federal List: no special status
CITES: appendix ii
State of Michigan List: special concern
IUCN Red List of Threatened Species: vulnerable
Male wood turtles form dominance hierarchies in the wild, and will often aggressively attack other males; females also exhibit aggressive behavior, which can be directed both toward males and other females. Older, larger males tend to be dominant over smaller individuals, and also have better success in fertilizing eggs (Kaufmann, 1992).
Courtship may include a mating "dance" in which the male and female face each other and swing their heads back and forth; perhaps more frequently the male simply pursues the female while nipping at her limbs and shell and then mounts her carapace. While thus positioned, the male may nip at the female's head and often thumps the female's carapace by straightening and then flexing his front limbs, and dropping his plastron onto the female's shell. Copulation usually occurs in shallow water on a sloping stream bank, though courtship may be initiated on land. Mating may occur at any time during the active season, but is probably most frequent in spring and fall, when the turtles are more aquatic.
In May or June, female wood turtles seek open, sunny nesting sites, preferring sandy banks adjacent to moving water whenever possible. The female excavates the nest with her hind feet, creating a globular cavity about 5 to 13 cm (2 to 5 inches) deep. Clutch size ranges from 3 to 18 eggs (usually 5 to 13). The eggs are carefully buried, and the females goes to considerable effort to smooth and obscure the nest site, but then departs, offering no further care to her offspring. Only one clutch is produced each year, and females may not reproduce every year (Harding, 1977, 1991, 1997).
Most wood turtle eggs never hatch; nest predation by raccoons, skunks, shrews, foxes, and other predators can typically result in high losses, sometimes approaching the entire year's reproductive effort for a turtle population when predator numbers are high. In a Michigan study, 70 to 100 percent of nests were typically lost each year, mostly to raccoons. For eggs fortunate enough to escape detection, incubation requires from 47 to 69 days, dependent mostly on temperature and moisture conditions in the nest. Hatchling G. insculpta generally emerge from their nests in late August or September and move to water. They appear not to overwinter in the nest, as occurs in some other freshwater turtle species (Ernst, Lovich, and Barbour, 1994; Harding, 1997: Tuttle, 1996).
In this species, the sex of the hatchling is independent of incubation temperature, a departure from the trend in closely related emydid species (such as Clemmys guttata and Emydoidea blandingii) in which embryonic sex differentiation is directly related to nest temperatures during the middle third of the incubation period (Ewert and Nelson, 1991).
Wood turtles in the wild usually reach sexual maturity between 14 and 20 years of age; in a Michigan study, most reproductive adults were in their third and fourth decade of life. Maximum lifespan in the wild is unknown, but can probably exceed the age of 58 obtained by a captive specimen (Ernst, Lovich, and Barbour, 1994; Harding 1991, 1997).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)
Average age at sexual or reproductive maturity (male)
Sex: male: 5840 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 5840 days.
The wood turtle (Glyptemys insculpta) is a species of turtle endemic to North America. It is in the genus Glyptemys, a genus which contains only one other species of turtle: the bog turtle (Glyptemys muhlenbergii). The wood turtle reaches a straight carapace length of 14 to 20 centimeters (5.5 to 7.9 in), its defining characteristic being the pyramidal shape of the scutes on its upper shell. Morphologically, it is similar to the bog turtle, spotted turtle (Clemmys guttata), and Blanding's turtle (Emydoidea blandingii). The wood turtle exists in a broad geographic range extending from Nova Scotia in the north (and east) to Minnesota in the west and Virginia in the south. In the past, it was forced south by encroaching glaciers: skeletal remains have been found as far south as Georgia.
It spends a great deal of time in or near the water of wide rivers, preferring shallow, clear streams with compacted and sandy bottoms. The wood turtle can also be found in forests and grasslands, but will rarely be seen more than several hundred meters from flowing water. It is diurnal and is not overtly territorial. It spends the winter in hibernation and the hottest parts of the summer in estivation.
The wood turtle is omnivorous and is capable of eating on land or in water. On an average day, a wood turtle will move 108 meters (354 ft), a decidedly long distance for a turtle. Many other animals that live in its habitat pose a threat to it. Raccoons are over-abundant in many places and are a direct threat to all life stages of this species. Inadvertently, humans cause many deaths through habitat destruction, road traffic, farming accidents, and illegal collection. When unharmed, it can live for up to 40 years in the wild and 58 years in captivity.
The wood turtle belongs to the family Emydidae. The specific name, insculpta, refers to the rough, sculptured surface of the carapace. This turtle species inhabits aquatic and terrestrial areas of North America, primarily the northeast of the United States and parts of Canada.[5] Wood turtle populations are under high conservation concerns due to human interference of natural habitats. Habitat destruction and fragmentation can negatively impact the ability for wood turtles to search for suitable mates and build high quality nests.
Formerly in the genus Clemmys, the wood turtle is now a member of the genus Glyptemys, a classification that the wood turtle shares with only the bog turtle.[6] It and the bog turtle have a similar genetic makeup, which is marginally different from that of the spotted turtle (Clemmys guttata), the only current member of the genus Clemmys.[7] The wood turtle has undergone extensive scientific name changes by various scientists over the course of its history.[6] Today, there are several prominent common names for the wood turtle, including sculptured tortoise, red-legged tortoise, and redleg.[6]
Although no subspecies are recognized, there are morphological differences in wood turtles between areas. Individuals found in the west of its geographic range (areas like the Great Lakes and the Midwest United States) have a paler complexion on the inside of the legs and underside of the neck than ones found in the east (places including the Appalachian Mountains, New York, and Pennsylvania).[8] Genetic analysis has also revealed that southern populations have less genetic diversity than the northern; however, both exhibit a fair amount of diversity considering the decline in numbers that have occurred during previous ice ages.[9]
Wood turtles grow to between 14 and 20 centimeters (5.5 and 7.9 in) in straight carapace length,[10] and reach a maximum of 23.4 centimeters (9.2 in).[6][8] They have a rough carapace that is a tan, grayish brown or brown color, with a central ridge (called a keel) made up of a pyramidal pattern of ridges and grooves.[10] Older turtles typically display an abraded or worn carapace. Fully grown, they weigh 1 kilogram (35 oz).[11] The wood turtle's karyotype consists of 50 chromosomes.[8]
The larger scutes display a pattern of black or yellow lines. The wood turtle's plastron (ventral shell) is yellowish in color[10] and has dark patches. The posterior margin of the plastron terminates in a V-shaped notch.[6] Although sometimes speckled with yellowish spots, the upper surface of the head is often a dark gray to solid black. The ventral surfaces of the neck, chin, and legs are orange to red with faint yellow stripes along the lower jaw of some individuals.[6] Seasonal variation in color vibrancy is known to occur.[8]
At maturity, males, who reach a maximum straight carapace length of 23.4 centimeters (9.2 in), are larger than females, who have been recorded to reach 20.4 centimeters (8.0 in).[8] Males also have larger claws, a larger head, a concave plastron, a more dome-like carapace, and longer tails than females.[12] The plastron of females and juveniles is flat while in males it gains concavity with age.[11] The posterior marginal scutes of females and juveniles (of either sex) radiate outward more than in mature males.[12] The coloration on the neck, chin, and inner legs is more vibrant in males than in females who display a pale yellowish color in those areas.[8] Hatchlings range in size from 2.8 to 3.8 centimeters (1.1 to 1.5 in) in length (straight carapace measurement).[12] The plastrons of hatchlings are dull gray to brown. Their tail usually equals the length of the carapace and their neck and legs lack the bright coloration found in adults.[10] Hatchlings' carapaces also are as wide as they are long and lack the pyramidal pattern found in older turtles.[12]
The eastern box turtle (Terrapene c. carolina) and Blanding's turtle are similar in appearance to the wood turtle and all three live in overlapping habitats. However, unlike the wood turtle, both Blanding's turtle and the eastern box turtle have hinged plastrons that allow them to completely close their shells. The diamondback terrapin (Malaclemys terrapin) has a shell closely resembling the wood turtle's; however its skin is gray in color, and it inhabits coastal brackish and saltwater marshes.[10] The bog turtle and spotted turtle are also similar, but neither of these has the specific sculptured surface found on the carapaces of the wood turtle.[13]
The wood turtle is found in most New England states, Nova Scotia, west to Michigan, northern Indiana and Minnesota,[8] and south to Virginia. Overall, the distribution is disjunct with populations often being small and isolated. Roughly 30% of its total population is in Canada.[11] It prefers slow-moving streams containing a sandy bottom and heavily vegetated banks. The soft bottoms and muddy shores of these streams are ideal for overwintering. Also, the areas bordering the streams (usually with open canopies[4] ) are used for nesting. Spring to summer is spent in open areas including forests, fields, bogs, wet meadows, and beaver ponds. The rest of the year is spent in the aforementioned waterways.[10]
The densities of wood turtle populations have also been studied. In the northern portion of its range (Quebec and other areas of Canada), populations are fairly dilute, containing an average of 0.44 individuals per 1 hectare (2.5 acres), while in the south, over the same area, the densities varied largely from 6 to 90 turtles. In addition to this, it has been found that colonies often have more females than males.[7]
In the western portion of its range, wood turtles are more aquatic.[14] In the east, wood turtles are decidedly more terrestrial, especially during the summer. During this time, they can be found in wooded areas with wide open canopies. However, even here, they are never far from water and will enter it every few days.[15]
In the past, wood turtle populations were forced south by extending glaciers. Remains from the Rancholabrean period (300,000 to 11,000 years ago) have been found in states such as Georgia and Tennessee, both of which are well south of their current range.[8] After the receding of the ice, wood turtle colonies were able to re-inhabit their customary northern range[16] (areas like New Brunswick and Nova Scotia).[8]
This species is oviparous, meaning these turtles produce offspring by laying eggs only and do not provide parental care outside of nest-building. Thus, the location and quality of nesting sites determine the offspring survival and fitness, so females invest significant time and energy into nest site selection and construction. Females select nest sites based on soil temperature (preferring warmer temperature nest sites), but not soil composition.[17] Average nest size is four inches wide and three inches deep. Also, females build nests in elevated areas in order to avoid flooding and predation. After laying eggs, female wood turtles will cover the nest with leaves or dirt in order to hide the unhatched eggs from predators, and then the female leaves the nest location until the next mating season. Nesting sites can be used by the same female for multiple years.[5] Because nest building occurs along rivers, females tend to spend more time along river areas, compared to male turtles.[18]
During the spring, the wood turtle is active during the daytime (usually from about 7:00 a.m. and 7:00 p.m.)[15] and will almost always be found within several hundred metres of a stream. The early morning and late afternoon are preferred foraging periods.[15] Throughout this season, the wood turtle uses logs, sandy shores, or banks to bask in sunlight.[19] In order to maintain its body temperatures through thermoregulation, it spends a considerable amount of time basking, most of which takes place in the late morning and late afternoon. The wood turtle reaches a peak body temperature of 37 °C (99 °F) after basking. During times of extreme heat, it has been known to estivate. Several reports mention individuals resting under vegetation, fallen debris and in shallow puddles. During the summer, the wood turtle is considered a largely terrestrial animal.[4] At night, its average body temperature drops to between 15 and 20 °C (59 and 68 °F)[20] and it will rest in small creeks or nearby land (usually in areas containing some sort of underbrush or grass).[15]
During warmer weather, the wood turtle stays in the water for a larger percentage of the time.[20] For this reason, during the winter months (and the late fall and early spring) it is considered an aquatic turtle.[4] November through February or March is spent in hibernation at the bottom of a small, flowing river. The wood turtle may hibernate alone or in large groups. During this period, individuals bury themselves in the thick mud at the bottom of the river and rarely move. During hibernation, it is vulnerable to flash floods. Emergence does not occur until March or sometimes April, months that mark the beginning of its activation period (males are typically more active than females at this time).[20]
Males are known to be aggressive, with larger and older turtles being more dominant. Larger males rank higher on the social hierarchy often created by wood turtle colonies. In the wild, the submissive turtle is either forced to flee, or is bombarded with physical abuses, which include biting, shoving, and ramming. Larger and more dominant males will sometimes try to remove a subordinate male while he is mating with a female. The defender will, if he does not successfully fight for his position, lose the female to the larger male. Therefore, among males, there is a direct relationship between copulation opportunities and social rank.[21] However, the outcome of encounters between two turtles is more aggression-dependent than size-dependent. The wood turtle that is more protective of his or her area is the victor. Physical bouts between wood turtles (regardless of sex) increases marginally during the fall and spring (times of mating).[22]
The wood turtle is omnivorous, feeding mainly on plant matter and animals both on land and in water. It eats prey such as beetles, millipedes, and slugs. Also, wood turtles consume specific fungi (Amanita muscaria and Leccinum arcolatum), mosses, grasses, various insects, and also carrion.[23] On occasion, it can be seen stomping the ground with alternating hits of the left and right front feet. This behavior imitates the vibrations caused by moles, sometimes causing earthworms to rise to the surface where they quickly become easy prey.[24] When hunting, the wood turtle pokes its head into such areas as dead and decaying logs, the bottoms of bushes, and in other vegetation. In the water, it exhibits similar behavior, searching algae beds and cavities along the sides of the stream or river.[23]
Many different animals are predators of or otherwise pose a threat to the wood turtle. They include snapping turtles, raccoons, otters, foxes, and cats. All of these species destroy unhatched eggs and prey upon hatchlings and juveniles. Several animals that often target wood turtle eggs are the common raven and coyote, which may completely destroy the nests they encounter. Evidence of predatory attacks (wounds to the skin and such) are common on individuals, but the northern populations tend to display more scarring than the southern ones. In addition to these threats, wood turtles also suffer from leech infestations.[25]
The wood turtle can travel at a relatively fast speed (upwards of 0.32 kilometers per hour (0.20 mph)); it also travels long distances during the months that it is active. In one instance, of nine turtles studied, the average distance covered in a 24-hour period was 108 meters (354 ft), with a net displacement of 60 meters (197 ft).[26]
The wood turtle, an intelligent animal, has homing capabilities. Its mental capacity for directional movement was discovered after the completion of an experiment that involved an individual finding food in a maze. The results proved that these turtles have locating abilities similar to that of a rat. This was also proved by another, separate experiment. One male wood turtle was displaced 2.4 kilometers (1.5 mi) after being captured, and within five weeks, it returned to the original location. The homing ability of the wood turtle does not vary among sexes, age groups, or directions of travel.[22]
The wood turtle takes a long time to reach sexual maturity, has a low fecundity (ability to reproduce), but has a high adult survival rate. However, the high survival rates are not true of juveniles or hatchlings. Although males establish hierarchies, they are not territorial.[4] The wood turtle becomes sexually mature between 14 and 18 years of age. Mating activity among wood turtles peaks in the spring and again in the fall, although it is known to mate throughout the portion of the year they are active. However, it has been observed mating in December.[27] In one rare instance, a female wood turtle hybridized with a male Blanding's turtle.[28]
The courtship ritual consists of several hours of 'dancing,' which usually occurs on the edge of a small stream. Males often initiate this behavior: starting by nudging the females shell, head, tail, and legs. Because of this behavior, the female may flee from the area, in which case the male will follow.[27] After the chase (if it occurs), the male and female approach and back away from each other as they continually raise and extend their heads. After some time, they lower their heads and swing them from left to right.[19] Once it is certain that the two individuals will mate, the male will gently bite the female's head and mount her. Intercourse lasts between 22 and 33 minutes.[27] Actual copulation takes place in the water,[19] between depths between 0.1 and 1.2 meters (0 and 4 ft). Although unusual, copulation does occur on land.[27] During the two prominent times of mating (spring and fall), females are mounted anywhere from one to eight times, with several of these causing impregnation. For this reason, a number of wood turtle clutches have been found to have hatchlings from more than one male.[21]
Nesting occurs from May until July. Nesting areas receive ample sunlight, contain soft soil, are free from flooding, and are devoid of rocks and disruptively large vegetation.[21] These sites however, can be limited among wood turtle colonies, forcing females to travel long distances in search of a suitable site, sometimes a 250 meters (820 ft) trip. Before laying her eggs, the female may prepare several false nests.[28] After a proper area is found, she will dig out a small cavity, lay about seven eggs[19] (but anywhere from three to 20 is common), and fill in the area with earth. Oval and white, the eggs average 3.7 centimeters (1.5 in) in length and 2.36 centimeters (0.93 in) in width, and weigh about 12.7 grams (0.45 oz). The nests themselves are 5 to 10 centimeters (2.0 to 3.9 in) deep, and digging and filling it may take a total of four hours. Hatchlings emerge from the nest between August and October with overwintering being rare although entirely possible. An average length of 3.65 centimeters (1.44 in), the hatchlings lack the vibrant coloration of the adults.[28] Female wood turtles in general lay one clutch per year and tend to congregate around optimal nesting areas.[19]
The wood turtle, throughout the first years of its life, is a rapid grower. Five years after hatching, it already measures 11.5 centimeters (4.5 in), at age 16, it is a full 16.5 to 17 centimeters (6.5 to 6.7 in), depending on sex. The wood turtle can be expected to live for 40 years in the wild, with captives living up to 58 years.[23]
The wood turtle is the only known turtle species in existence that has been observed committing same-sex intercourse.[29] Same-sex behavior in tortoises is known in more than one species.
The wood turtle exhibits genetic sex determination, in contrast to the temperature-dependent sex determination of most turtles.[30]
Specific mating courtship occurs more often in the Fall months and usually during the afternoon hours from 11:00 to 13:00 when many of the turtles are out in the population feeding.[31] Mating is based on a male competitive hierarchy where a few higher ranked males gain the majority of mates in the population. Male wood turtles fight to gain access to female mates. These fights involve aggressive behaviors such as biting or chasing one another, and the males defend themselves by retreating their heads into their hard shells. The higher ranked winning males in the hierarchy system have a greater number of offspring than the lower ranked male individuals, increasing the dominant male's fitness.[32] Female wood turtles mate with multiple males and are able to store sperm from multiple mates.[32] Although the mechanism of sperm storage is unknown for the Wood Turtle species, other turtle species have internal compartments that can store viable sperm for years. Multiple mating ensures fertilization of all the female's eggs and often results in multiple paternity of a clutch, which is a common phenomenon exhibited by many marine and freshwater turtles.[32] Multiple paternity patterns have been made evident in wood turtle populations by DNA fingerprinting. DNA fingerprinting of turtles involves using an oligonucleotide probe to produce sex specific markers, ultimately providing multi-locus DNA markers.[33]
Despite many sightings and a seemingly large and diverse distribution, wood turtle numbers are in decline. Many deaths caused by humans result from: habitat destruction, farming accidents, and road traffic. Also, it is commonly collected illegally for the international pet trade. These combined threats have caused many areas where they live to enact laws protecting it.[7] Despite legislation, enforcement of the laws and education of the public regarding the species are minimal.[34]
For proper protection of the wood turtle, in-depth land surveys of its habitat to establish population numbers are needed.[35] One emerging solution to the highway mortality problem, which primarily affects nesting females,[14] is the construction of under-road channels. These tunnels allow the wood turtle to pass under the road, a solution that helps prevent accidental deaths.[7] Brochures and other media that warn people to avoid keeping the wood turtle as a pet are currently being distributed.[35] Next, leaving nests undisturbed, especially common nesting sites and populations, is the best solution to enable the wood turtle's survival.[36]
While considered nationally as threatened by COSEWIC, the wood turtle is listed as vulnerable within the province of Nova Scotia under the Species at Risk Act. The species is highly susceptible to human land use activities, and special management practices for woodlands, rivers and farmland areas as well as motor vehicle use restrictions and general disruption protection during critical times such as nesting and movement to overwintering habitat is closely monitored.[37] Since 2012, the Clean Annapolis River Project (CARP) has provided research and stewardship for this species including the identification of crucial habitats, distribution and movement estimation, and outreach.[38]
The wood turtle (Glyptemys insculpta) is a species of turtle endemic to North America. It is in the genus Glyptemys, a genus which contains only one other species of turtle: the bog turtle (Glyptemys muhlenbergii). The wood turtle reaches a straight carapace length of 14 to 20 centimeters (5.5 to 7.9 in), its defining characteristic being the pyramidal shape of the scutes on its upper shell. Morphologically, it is similar to the bog turtle, spotted turtle (Clemmys guttata), and Blanding's turtle (Emydoidea blandingii). The wood turtle exists in a broad geographic range extending from Nova Scotia in the north (and east) to Minnesota in the west and Virginia in the south. In the past, it was forced south by encroaching glaciers: skeletal remains have been found as far south as Georgia.
It spends a great deal of time in or near the water of wide rivers, preferring shallow, clear streams with compacted and sandy bottoms. The wood turtle can also be found in forests and grasslands, but will rarely be seen more than several hundred meters from flowing water. It is diurnal and is not overtly territorial. It spends the winter in hibernation and the hottest parts of the summer in estivation.
The wood turtle is omnivorous and is capable of eating on land or in water. On an average day, a wood turtle will move 108 meters (354 ft), a decidedly long distance for a turtle. Many other animals that live in its habitat pose a threat to it. Raccoons are over-abundant in many places and are a direct threat to all life stages of this species. Inadvertently, humans cause many deaths through habitat destruction, road traffic, farming accidents, and illegal collection. When unharmed, it can live for up to 40 years in the wild and 58 years in captivity.
The wood turtle belongs to the family Emydidae. The specific name, insculpta, refers to the rough, sculptured surface of the carapace. This turtle species inhabits aquatic and terrestrial areas of North America, primarily the northeast of the United States and parts of Canada. Wood turtle populations are under high conservation concerns due to human interference of natural habitats. Habitat destruction and fragmentation can negatively impact the ability for wood turtles to search for suitable mates and build high quality nests.
.jpg)
.jpg)
