Michigan State University masthead

wood turtle

wood turtle
Glyptemys insculpta

Image of wood turtle (male)Description

The scientific name of this species means "sculptured turtle", and its rough, brownish carapace does look as if it was carved from wood. Each scute has deep, circular growth rings crossed by ray-like ridges. The plastron is yellow with a black blotch at the outer edge of each scute and has a V-shaped notch at the base of the tail. The head and upper legs are mostly black or dark brown (rarely speckled with yellow or white), while the neck, lower legs, and other soft parts are yellow or orange. Mature males have higher shells and longer, thicker tails than females.

Adult Carapace Length:

6.3 to 9.4 inches (16 to 24 cm).

Habitat and Habits

Wood turtles occur in and near rivers and streams of the north woods. They prefer streams with sandy bottoms and avoid rocky sections with fast current. These turtles often bask on logs or grassy banks, and they spend much time wandering through adjacent swamps, woods, and meadows, especially in summer. Most wood turtles inhabit a rather small home range, living much of their lives (perhaps 40 years or more) within an area of a few acres. They feed (both in and out of water) on insects, worms, slugs, snails, carrion, algae, berries, willow leaves, and numerous other items. Some specimens have been observed capturing worms by thumping the ground with the forefeet or plastron; the vibration apparently disturbs the worms and brings them to the surface. Wood turtles depend largely on concealment for protection and rarely bite. When leaving the water, they often throw sand or dirt over their shells with quick backward strokes of the front feet, helping them to blend with their surroundings. Lacking the protective plastral hinge of the box turtle, wood turtles are quite vulnerable when on land, and specimens are often found with one or more limbs missing due to attacks by predators. The ability of some turtles to survive such crippling injuries is noteworthy.

Image of wood turtle (juvenile)Reproduction

Courtship and mating can occur from spring through fall. Courting behavior may include a "dance" in which the male and female face each other and swing their heads from side to side. Later the male may climb on the female's shell, gripping the edges with his claws, and repeatedly strike her carapace with his plastron. Mating usually takes place in water on a sloping stream bank. Most females nest in June, burying from 4 to 18 elliptical eggs in an open, sunny location. Incubation can take from 45 to 80 days, depending on nest temperatures and humidity. Many nests are lost to predators, particularly raccoons. The brown or gray hatchlings have long thin tails and lack the yellow or orange skin color of the adults and older juveniles. They may grow from a hatching carapace length of about 1.25 inches (3.2 cm) to an adult size of about 6.3 inches (16 cm) in 12 to 14 years in a favorable environment. In wood turtles the number of growth rings (annuli) in each scute can be used to determine an approximate age for juvenile and young adult specimens, but this method becomes much less reliable for turtles over 20 years old.

Range and Status

Wood turtles occur in the northern Lower Peninsula and the Upper Peninsula. Scattered records from the southern LP may represent released specimens. These turtles can be locally common in suitable habitat with minimal human disturbance, but some populations have declined significantly over the past two or three decades. Collecting wood turtles for pets (both purposefully and incidentally) has significantly reduced some populations. Many wood turtles are killed on roads built along northern rivers. This species may be less affected by habitat loss than by direct human exploitation and accidental destruction. Wood turtles are listed as a "species of special concern" by the Michigan Department of Natural Resources and are protected by state wildlife regulations. They may not be taken from the wild or possessed without a scientific collector's permit issued by the DNR.

Image of wood turtle Acknowledgement

James Harding
MSU Museum
Michigan State University
East Lansing, MI 48824
(517) 353-7978