(LeConte, 1830)
Wood turtle
Recognition
This medium-sized (to 23 cm) turtle has a keeled, sculptured carapace which is broad, low, and rough: each large scute supports an irregular pyramid formed by a series of concentric growth annuli and grooves. Vertebrals are broader than long, and posterior marginals are strongly flared and serrated. The carapace is slightly widened posteriorly and may be slightly indented at the bridge. It is gray to brown, often with black or yellow lines radiating from the upper posterior corners of the pleurals. Undersides of the marginals and bridge often have dark blotches along the seams. The yellow plastron has a pattern of oblong dark blotches on each scute. Its hindlobe is notched posteriorly, and the plastral formula is: an > gul > abd >< pect > fem > hum. The blackish head is largest in the Clemmys, but is still moderate in size. A nonprojecting snout and a notched upper jaw are present. Other skin is dark brown, often with some orange or red pigment on the neck and forelegs. The tail is rather long.
The diploid chromosome number is 50: 8 pairs of macrochromosomes with median or submedian centromeres, 5 pairs of macrochromosomes with terminal to subterminal centromeres, and 12 pairs of microchromosomes (Bickham, 1975).
The male has a long, thick tail, with the vent posterior to the carapacial rim; a concave plastron with a deep end notch; and prominent scales on the anterior surface of the forelimbs.
Distribution
The wood turtle ranges from Nova Scotia south to northern Virginia and west through southern Ontario and New York to Michigan, Wisconsin, eastern Minnesota, and northeastern Iowa.
Geographic Variation
No subspecies have been described, but those from west of the Appalachian Mountains are paler than eastern individuals.
Habitat
Next to the box turtles (Terrapene) and the tortoises (Gopherus), this is the most terrestrial North American turtle. It can be found in most habitats within its range. We have observed it in deciduous woods, woodland bogs, and marshy fields (in Pennsylvania, Maryland, Virginia, and New York). Most activity within these habitats occurs in the riparian zones along streams, brooks or marshes.
Natural History
Males mature at carapace lengths of 19.2-20.0 cm; females mature at carapace lengths of 15.8-18.5 cm. Both sexes mature between the ages of 14-18 years (Garber, 1989; Lovich et al., 1990a; Farrell and Graham, 1991, Ross et al., 1991; Brooks et al., 1992). Elements of the female reproductive cycle of Clemmys insculpta in Nova Scotia were described by Powell (1967). A single female collected in September contained 10 follicles ranging in size from 11-17 mm, representing one clutch. Others collected on June 5 contained oviducal eggs, and nesting activity was observed in the same area on June 21. Only one clutch is laid per season as virtually all large follicles are ovulated at one time. Of 12 gravid females, 8 lacked large follicles and 4 had only one each. The amount of ovarian fat is correlated with maturation of ova and increases as ova dry weight increases. The increase in ovarian fat is accompanied by a corresponding decrease in the fat content of other body tissues (Brenner, 1970). The male reproductive cycle has not been described.
Mating can occur at any time during the active season, but peaks are evident in the spring and fall. Most courtships occur in the late afternoon, and mating usually takes place under water. Courtship is usually started by the male, but female instigated courtship does occur. Males are rough lovers. They pursue females; smell her shell, head, tail, and legs; and, if facing her, bob and sway their heads in front of her (she may respond in kind). The male quickly mounts her carapace from the rear, and locks his claws under her marginals. He then rubs his plastron against her shell, and bites her head and shell. Biting is alternated with thumping behavior in which he pounds his plastron against her shell. The male's tail is then wrapped around hers and his penis inserted into her vent. He also gently shakes from side to side (a behavior apparently needed for proper insemination) (Harding and Bloomer, 1979; Brewster and Brewster, 1988; Ernst and McBreen, 1991c; Kaufmann, 1992b). Plastron to plastron matings may also occur (Tronzo, 1993; Mitchell and Mueller, 1996). DNA testing has revealed multiple paternity (Galbreath, 1993).
Nesting occurs from May to early July. The nests are flask-shaped and about 10 cm deep.
Only one clutch of 4-18 eggs (usually about 7-10) is laid a season. The eggs are elliptical, whitish, have smooth, thin shells, and measure 27.0-49.0 x 19.5-26.3 mm (Harding and Bloomer, 1979; Ernst and McBreen, 1991c; Farrell and Graham, 1991). Natural incubation takes 70-80 days.
Hatchlings are gray brown and lack any orange or red pigment on the neck or legs. The tail is long: about equal to the carapace length. The keelless shell is low and about as broad as long (28.0-27.9 x 27.4-35.9 mm). Olfaction, vision, positive geotaxis, and auditory cues of nearby running water may be used as cues by emerged hatchlings to find wet habitats once they have left the nest (Tuttle and Carroll, 1997).
The wood turtle is omnivorous. Plants eaten include filamentous algae, moss, grass, willow leaves, strawberries, blackberries, and sorrel. Animal foods include a wide variety of insects and mollusks as well as earthworms and tadpoles. Surface (1908) found plant remains in 76% and animal remains in 80% of the 26 specimens he examined. He also found bird remains, indicating scavenging tendencies. Captives readily eat apples and canned dog food, and they relish hard-boiled eggs. It sometimes engages in a strange feeding strategy, "worm stomping", to lure earthworms out of their burrows. The turtle stumps the earth with its forefeet (Harding and Bloomer, 1979; Kaufmann, 1986, 1989; Kaufmann et al., 1989; Tuttle and Carroll, 1997). A stomping turtle typically takes a few steps forward and then stomps several times with one front foot and then the other at a rate of about one stomp per second. The plastron may also be banged against the ground during the process. Any earthworm brought to the surface is eaten. The worms may believe the stumping represents vibrations caused by raindrops and come to the surface to forage in the rain.
C. insculpta is diurnal and often wanders about on land during the midday hours. It is fond of basking in the morning, on a log in the middle of a large creek, for example. In the dry summer months it often soaks in mud puddles. It is active from late March to mid October. The winter months are spent in hibernation in the mud bottom of some waterway or in a hole in the bank.
IUCN Red List Status (1996)
Vulnerable (A1abcd+2cd). Recently the numbers of wood turtles have alarmingly decreased because of collection for the pet trade. Nearly all states within its range have either given it protection as an endangered or threatened species or are seriously considering doing so; the species is completely protected in Michigan and throughout the Great Lakes region.