Wood Turtle

Description

Wood turtles can grow to an upper shell (carapace) length of 25 cm, with males reaching slightly larger sizes than females. The upper shell has a sculpted appearance owing to the raised concentric growth rings on each scute (enlarged scales on the shell) that give them a pyramidal shape. It is also heavily serrated along the rear edge and has a keel — or raised ridge — running down the centre. The upper shell is tan, greyish brown or brown with yellow and black lines radiating from the centre of each scute. The bottom shell (plastron) is yellow, with a large dark blotch on the outer corner of each scute. The head is black, the upper surfaces of the limbs are generally brown and the neck, underside of the legs and tail are yellow, orange or red.

Distribution and Habitat

In Canada, wood turtles are found in South-Central Ontario, South-Central Quebec and much of New Brunswick and Nova Scotia. Their distribution is patchy, particularly in Ontario and Quebec, where small, isolated populations are separated from each other by large distances. The wood turtle is also found throughout the Northeastern United States from Maine to Pennsylvania, West Virginia and Virginia, as well as on the west side of the Great Lakes in Northern Michigan, Wisconsin, Eastern Minnesota and Northern Illinois.

Wood turtles live in shallow, meandering (i.e., winding) rivers and streams that typically have clear water, moderate current and a sand, gravel or cobble bottom. As temperature increases in the spring, wood turtles move into nearby terrestrial habitats (e.g., forest, thickets and forest clearings) or wetlands, where they spend much of the summer. Wood turtles prefer a mix of forest and open-canopy habitats, which provide a range of temperatures and a variety of food sources. Females nest in sunny habitats where warm temperatures help the eggs develop, such as in sand or gravel bars along the river, sandy beaches, river banks or along road shoulders. Wood turtles hibernate on the river bed in deeper sections of the river. Individuals can have large home ranges that span several kilometres along the river. During the summer months, wood turtles may move as far as 900 m away from the river, although they are usually found within a few hundred metres of the river.

Did you know?
Wood turtles are very intelligent, and some individuals employ an impressive foraging strategy. These turtles stomp their front feet (and sometimes their shell) on the ground to create vibrations. These vibrations cause earthworms, one of their primary prey species, to come to the surface so the turtles can eat them. The reason these vibrations attract worms to the surface remains something of a mystery. This activity may mimic the vibrations caused by raindrops hitting the ground, enticing the worms to the surface to avoid flooded burrows. Another possibility is that these vibrations mimic those caused by the movement of underground predators such as moles, causing the worms to flee toward the surface.

Reproduction and Development

Wood turtles typically mate in the spring or fall, although some mating can occur during the summer. Females lay a clutch of 1 to 20 eggs from late May to early July. In Canada, females typically lay a single clutch of eggs each year, although some females may not nest every year. Hatchlings emerge from the eggs between mid-August and early October and have an upper shell length averaging 3.3–3.65 cm. Unlike most other turtle species in Canada, the sex of the hatchlings is determined genetically rather than by the incubation temperature of the eggs.

In Canada, wood turtles do not reach sexual maturity until they are 11–22 years old. Freshwater turtle eggs, hatchlings and juveniles have low survival; over her entire lifespan, a female wood turtle may produce only a few eggs that survive to adulthood. Once individuals reach adulthood, however, they have high survival and may live for over 80 years. Small clutch sizes, delayed maturity and low survival from egg to adult mean that wood turtle populations grow very slowly, making long adult lifespans necessary to maintain stable populations.

Diet and Predation.

Wood turtles are omnivores and eat a variety of plants and small animals. Plant material (e.g., leaves, seeds and berries), mushrooms, earthworms, slugs, amphibian larvae, insects and carrion (dead animals) usually comprise most of their diet. Unlike many freshwater turtles, wood turtles forage extensively on land as well as in the water. Mammals (e.g., raccoons, foxes, skunks and coyotes) and ravens are the main predators of wood turtles and their nests. Nest predation rates can be very high (sometimes 100% in some years) in areas with abundant nest predators. Hatchlings are also eaten by many other animals, including snapping turtles, large fish and various birds.

Threats

Because wood turtles have long lifespans and very slow population growth, losing even a small number of adults each year can cause population declines. Consequently, the death of turtles on roads is the most severe threat to wood turtles in Canada, and it is believed to be causing population declines in many parts of the species’ range. Farm equipment also kills wood turtles, particularly in areas with intensive agriculture. Ongoing habitat loss, such as converting natural areas to agricultural land, is another major threat to this species. Some of Canada’s turtle species, including the wood turtle, are also threatened by poaching and illegal wildlife trafficking. Because poachers can rapidly remove a large number of adults from the population, illegal collection is a serious threat that can cause significant and often irreversible declines. Other threats to wood turtles in Canada include an increased abundance of nest predators (e.g., raccoons) in many human-settled areas, activities that alter stream flow (e.g., dams), logging and climate change.

Status and Conservation

Globally, the wood turtle is listed as endangered by the International Union for Conservation of Nature. The Canadian Species at Risk Act (SARA) also lists it as threatened. This legislation, as well as provincial legislation, provides important protection for threatened and endangered species and their habitat, including the wood turtle. However, these laws do little to address some threats such as the death of wood turtles on Canada’s vast road network. Additional efforts are necessary to address these threats and halt population declines. For example, turtle mortality can be mitigated along roads by installing eco-passages, tunnels that allow turtles to safely cross under the road, combined with fences that prevent them from accessing the road. People can also help reduce turtle mortality on roads by watching for turtles on roads and moving them off the road whenever it is safe to do so.