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U of T student studies the threat posed to local amphibians by GTA traffic

Anyone who has played the 1980s video game Frogger knows that frogs and busy roads don’t mix.

Up to one million amphibians, reptiles, mammals, and birds are killed by motor vehicles on Greater Toronto roads each year. In fact, the toll is so great that road deaths are the second biggest threat, behind only habitat loss, to many at-risk species in the province.

nicole regimbalA fourth-year graduate student at the University of Toronto recently analyzed amphibian population and mortality data for 23 locations across the GTA – an effort that could help determine high-risk areas that could benefit from “eco-friendly” activities. tunnels” that allow frogs and other creatures to safely cross roads by going underneath.

“We wanted to see if the species present in the area were the same species that were experiencing mortality,” says Regimbal, a University College fellow who is completing a double major in ecology and evolutionary biology and environmental ethics.

It found that in two study areas in the Rouge River watershed north of Toronto, four of the nine frog species had disproportionately higher mortality rates: the American toad, the green frog, the gray tree frog, and the leopard frog. North.

In general, frogs are vulnerable because they are slow moving; paths are crossed frequently to travel from one habitat to another; and being cold blooded-, they are attracted by the heat of the roads. American toads are at risk as they travel long distances at night during their relatively long breeding season. The green frog, meanwhile, takes long walks during migration. The Northern Leopard Frog has little developed avoidance behavior, even in the face of approaching motor vehicles. And the Gray Treefrog is a particularly active and itinerant species.

A potential solution to the threat already exists in regions such as the Heart Lake Conservation Area in the Etobicoke Creek watershed. Three tunnels or ecological passages that pass under the roads provide amphibians with a safe underground route. They are especially effective in combination with fences that prevent frogs from crossing roads and divert them into tunnels.

A leopard frog uses a tunnel to safely cross under a road (photo courtesy of Toronto and the Region Conservation Authority)

Regimbal’s collaborators on the project were jonathan ruppertadjunct professor in the department of ecology and evolutionary biology (EEB) and senior research scientist for the Toronto Conservation Authority and the TRCA Region, and andrew chinBSE and TRCA research analyst.

The TRCA is one of 36 conservation authorities in Ontario with a mandate to protect natural environments. It oversees a region comprising nine watersheds and stretching from Ajax to Mississauga, Ontario, and from Lake Ontario to Dufferin County.

Ruppert says the new analysis will help make decisions about building new ecological passageways where they are needed most.

“It’s our first big case study within our jurisdiction to show that species are using them, and not just reptiles and amphibians, but mammals as well,” he says.

After graduating in the spring, Regimbal will enter the graduate program in ecology and evolutionary biology at U of T and plans to study the relationship between global change, the movement of organisms, and conservation.

“The frog mortality study was very satisfying and personally solidified my desire to pursue a career in research,” says Regimbal. “Sometimes I find myself overwhelmed by the magnitude of the problems we face. But this work felt significant as a first step towards the implementation of measures that can have very positive impacts.

“It was reassuring to feel that I contributed to leaving a positive mark on the world, regardless of the scale.”

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