At risk but holding on: Northern map turtles are still common in this eastern Ontario lake

The northern map turtle is considered a species at risk in Canada, but in at least one eastern Ontario lake theyappear to be doing slightly better.

In Canada, the turtles with their distinctive shellsare only found in Ontario and Quebec, where they love open water and sunning themselves in groups on nearby rocks.

And while the turtle population on Opinicon Lake is doing "fairly well," things aren't perfect, saidGrgory Bult, a wildlife biologist at Carleton University.

"We've seen a pretty big increase in the number of what we call propeller injuries on these turtles in the last 20 years," said Bult, who has been studying and tracking the turtles onthe North Frontenac lake since 2003.

Despite their relatively stable population numbers on the lake, 13 per cent of the female turtles have been struck by boats, he said.

It's not just in the water they face danger, he added, noting they'refrequently hit by vehicles when crossing roads.

Several turtle speciesat risk

The northern map turtle is one of several speciesin the province that are facing or could face a decline in their population.

Others include the Blanding's turtle, the eastern musk turtle and the snapping turtle (the latter two being considered of "special concern" in Ontario, rather than endangered).

Several things make map turtles distinctive, including their shell pattern, their social nature and the size discrepancy between males and females.

Not only do the turtles sun together, but they also spend winters hibernating together and researchers like Bult suspect their size differences may be reflective of that behaviour.

Female map turtles are more than double the size of their male counterparts, who aren't territorial and don't tend to fight each other.

That means flexing alarger shell isn't necessarily an advantage males need, Bult said but it could be a benefit for females.

"The females are huge compared to the males," he said."[Males]don't have an advantage of getting big, whereas females have that advantage because the bigger they are, the more eggs and the bigger eggs they can lay."

Ottawa Morning5:40Summer species profile: Map turtles

We talk to Gregory Bult, an Ottawa area wildlife biologist to learn more.

Map shells

Because of their larger size, the females are sometimes mistaken for snapping turtles, but Bult said spying ashorter tail is a good indication someone's in the presence of the gentler reptile.

Another good indication is their "stunning"shells, said Bult, on whichan intricate network of yellow lines overlaythe brown or olive-green background, giving the look of a topographic map.

The turtles also do their part to keep the population of thehighly invasivezebra mussel under control, Bult said, as they feast on them in lakes.