Turtles are a welcome and familiar site in the Kawarthas. They can be found in a variety of habitats such as lakes, ponds, rivers, marshes, and bogs. Some species are very particular about where they live. Map turtles, for example, prefer larger rivers or lakes, and may be spotted along the Trent-Severn Waterway. Other species, such as Painted turtles, can be found in a wider variety of habitats.
Turtles are ectothermic – more commonly known as cold-blooded – meaning that they cannot generate their own body heat. They warm themselves by basking in the sun, and retreat to the water when they need to cool off.
Turtles are most frequently observed in June, during the height of their nesting season. Females are often found crossing roads to reach traditional nesting sites or laying eggs in the gravel along roads. Turtle nests are laid in soil that is easy to dig and provides the correct amount of moisture so the eggs do not get too dry or too moist during incubation. Since the eggs are incubated by the sun’s warmth, nests are usually laid in a spot where there is not much vegetation to shade the ground.
Incubation times vary depending on the weather conditions over the summer, but the eggs generally hatch in late summer or early fall. The gender of many turtles, including all of the species found in the Kawarthas, is determined by incubation temperatures. A long hot summer means that more of the young turtles will develop as females.
Less than 1 in a hundred turtle eggs laid will hatch and grow into an adult turtle. Unlike birds, turtles do not tend their nests once laid, nor care for their young once they hatch. Once the female has finished laying her eggs she never sees them again. Nests are easily found and destroyed by predators such as raccoons, skunks, foxes and coyotes looking for an early summer meal. The babies that do hatch are vulnerable to predators on land and in the water and few ever reach maturity (8-25 years of age depending on the species).
Turtle reproduction (mating, nesting, hatching) video by biologist Brennan Caverhill:
However, adult turtles have few natural predators and enjoy a high survival rate. Most species live at least 30-40 years and some species can live to over 100 years! But it can take decades of nesting for just one egg to survive to replace the turtle that laid it.
Seven of the eight species of turtle in Ontario have been designated as “species at risk”. As is the case for many species at risk, habitat destruction has played a major role in the decline of turtles. Many of the marshes, swamps, bogs and fens that turtles once called home have been drained, filled, or otherwise altered.
Roads have been built through several of the remaining wetlands, and as a result road mortality is now a major threat to turtles. The majority of the turtles killed by cars are adult females on their way to or from nesting sites, which means that fewer eggs are laid every year and there is an even smaller chance that those killed by cars will be replaced in the future.
Other threats include collection for food or the pet trade, pollution, competition with non-native turtles such as red-eared sliders, and the increasing populations of predators who are benefiting from human settlement.
(Adapted from Varrin, R. (in press). Turtles of the Kawarthas. In, Nature in the Kawarthas.Peterborough Field Naturalists.)