Painted Turtle

Description

The painted turtle is a medium-sized freshwater turtle with a smooth, oval-shaped upper shell (also known as a “carapace”). Females are larger than males and have a maximum carapace length of just over 26 cm. The carapace is olive to black with bright red markings along the sides. The eastern painted turtle's bottom shell (also known as a “plastron”) is usually solid yellow, although a small dark blotch may be present in the centre. Midland painted turtles also have a yellow plastron but with a large dark blotch in the centre. Western painted turtles have an ornate plastron that is orange to red with a pattern of dark, reticulated lines. The skin is olive to black with bright yellow stripes in the case of the western painted turtle, whereas the eastern and midland painted turtles have a mix of yellow and red stripes. Painted turtles have two tooth-like projections called “bicuspid tomiodonts” at the front of the upper beak — a feature that distinguishes them from other freshwater turtles in Canada. They have webbed feet with pronounced claws, and males have elongated claws on the front feet.

Distribution and Habitat

The range of the western painted turtle extends from Vancouver Island eastward across the southern margin of the country to the north shore of Lake Superior in northern Ontario. The midland painted turtle is found throughout south and central Ontario, east of Lake Superior, and southwestern Quebec. The eastern painted turtle is found in southern New Brunswick and the southwestern half of Nova Scotia. These subspecies hybridize where their distributions overlap. In the United States, the painted turtle has an extensive distribution that extends from coast to coast across the northern part of the country, throughout most of the eastern and midwestern states, and in scattered populations in the southwest.

Painted turtles live in shallow aquatic habitats with still or slow-flowing water, a soft bottom, abundant vegetation and lots of basking sites such as logs or vegetation hummocks. They are mainly found in lakes, slow-flowing rivers and streams, ponds and wetlands such as bogs, marshes and swamps. Females nest in sunny habitats where warm temperatures help the eggs develop, such as the shorelines of rivers or lakes, gravel road shoulders and fields. Females have high fidelity to their nest sites, meaning they often return to the same nesting location each year. Painted turtles hibernate at the bottom of shallow water bodies, such as wetlands, ponds or shallow bays of lakes.

Did you know?
Painted turtles are North America's most cold-tolerant turtle species. Unlike most other freshwater turtles, many painted turtle hatchlings spend their first winter underground in their nest cavity and emerge the following spring. They can remain unfrozen at temperatures as low as -11°C, a process known as “supercooling.”

Reproduction and Development

Painted turtles typically mate in the spring, although some mating occurs in late summer and fall. Females nest between late May and early July. Western painted turtles — the largest subspecies — lay 4–23 eggs per clutch, midland painted turtles lay 3–17 eggs per clutch, and the smaller eastern painted turtles lay 1–11 eggs per clutch. In Canada, most females lay one clutch of eggs each year. However, some females do not reproduce yearly, while others may lay two clutches in a year. Hatchlings emerge from the eggs between late August and early October and have a carapace length averaging 2.66 cm. Like many freshwater turtles, painted turtles have temperature-dependent sex determination, meaning the sex of the offspring is determined by the incubation temperature of the eggs. Cooler temperatures produce males, while warmer temperatures produce females.

In Canada, female painted turtles may not reach sexual maturity until they are 12–15 years old, while males may take up to 7–10 years to mature. Freshwater turtle eggs, hatchlings and juveniles have low survival rates, and very few eggs survive to adulthood. Once individuals reach adult sizes, however, they have high annual survival and may live for over 100 years. Small clutch sizes, delayed maturity and low survival from egg to adult means that painted turtle populations grow very slowly, making long adult lifespans necessary to maintain stable populations.

Diet and Predation

Painted turtles are omnivores and eat a variety of plants and small animals. Their diet includes terrestrial and aquatic plants, leeches, molluscs (e.g., snails and clams), small crustaceans, insects, amphibians and their larvae, and carrion (dead animals). mammals (e.g., raccoons, foxes, otters and coyotes) are the main predators of painted turtles and their nests, while corvids (ravens and crows) are also major predators of adults and juveniles. Hatchlings are also eaten by many other animals, including wading birds, eagles and hawks, snakes, bullfrogs, snapping turtles and fish.

Threats

Road mortality is the most serious threat to painted turtles in Canada, as the death of even a small number of adults each year can cause population declines. Ongoing habitat destruction and fragmentation from urban and agricultural expansion also threaten many populations. Other threats include increased abundance of nest predators (e.g., raccoons) in many human-settled areas, commercial and recreational fishing (e.g., bycatch and the ingestion of fishing hooks), introduction and spread of invasive species such as the European common reed (Phragmites australis), logging, pollution and climate change.

(See also Invasive Species in Canada: Plants; Invasive Species in Canada: Animals)

Status

Globally, the painted turtle is listed as Least Concern by the International Union for Conservation of Nature (IUCN). However, this species faces many threats, and its long lifespan and slow reproduction make populations especially vulnerable to decline. For this reason, all subspecies have been identified as species at risk under the Canadian Species at Risk Act (SARA) in at least part of their range. Under this legislation, the western painted turtle was split into three populations: the Pacific coast population is listed as threatened, the intermountain-rocky mountain population is listed as special concern, and the prairie/western boreal-Canadian Shield population was assessed as not at risk. The midland and eastern painted turtle are both listed as special concern under this Act.