U of T, TRCA frog mortality research project highlights eco-friendly infrastructure need

A research project out of the University of Toronto and the Toronto and Region Conservation Authority (TRCA) is showing a disproportionate number of frogs are dying on roads in certain parts of the GTA, including in the Rouge National Urban Park and Humber River areas.

“Amphibians are generally very vulnerable because they’re small, and they’re slow and they lack avoidance behaviours and they’re actually attracted to roads for thermal regulation,” Nicole Regimbal, an ecology and evolutionary biology and environmental ethics student at the University of Toronto, said.

She is a key force behind the new project that monitored several areas in 2020 and 2021 and showed four frog species (American toads, green frogs, grey tree frogs and the northern leopard frogs) have a higher vulnerability of road mortality.

Regimbal said American toads travel mostly at night, green frogs travel long distances and northern leopard frogs won’t do anything to move out of the way of oncoming vehicles while grey tree frogs have avoidance tendencies but can avoid eco-protective measures.

She said the issue is cause for concern given the important role frogs play in wetland ecosystems, such as controlling and consuming bugs while also serving as a food force for bigger predators.

“I mean as predator, as prey, really if you remove or see a drop in any instrumental aspect of an ecosystem like that there’s going to be cascading effects,” Regimbal told CityNews.

“They’re also really important indicators of overall environmental health, so really the frog is who you look at to see is this wetland health or not. They’re very susceptible to contaminants, pollutants and stuff like that.”

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At the Heart Lake Conservation Area in Brampton, two polycarbonate fibre tunnels were built right into Heart Lake Road during a reconstruction project.

“On the roads here there were thousands of dead frogs that were occurring every year,” David Lawrie, an ecosystem and climate science research scientist with the TRCA, said.

He said the devices allow frogs and other amphibians to cross underneath the road, coaxed to the passage by low-level fencing along the side of the road.

“The cost of this is really minimal, so the more support and active community members can be the more of these that can be implemented,” Lawrie said, noting if the problem is left unchecked it could create bigger environmental problems.

“It definitely drops down the population levels because it’s such a high mortality rate over the long term the likelihood the population would persist would decline dramatically.”

Meanwhile, Regimbal said she hopes the project will serve others well into the future. She said municipalities should look at adding similar devices during road reconstruction projects in areas of need and failing that, there should occasional seasonal nightly closures (peak season ranges between April and July) to help protect the population.

“We’ve known based on what’s happening at Heart Lake that it’s effective, but having the numbers and having the paper kind of supporting that it’s effective is really what’s necessary to go to legislators and say, ‘Hey, I want an eco-passage on this road and this is how we know it works,’” she said.

City of Toronto updating wildlife mapping to identify areas to protect frogs, wildlife: spokesperson

CityNews contacted the City of Toronto to ask about the research project to see how the municipality is working to address the concerns raised.

A spokesperson said in a statement that projects that fall under the public right-of-way, green infrastructure standards such as permeable pavement, green gutters, bioswales and other technologies are put in place to “improve the city’s resilience to climate change and benefit wildlife.”

With respect to the Rouge National Urban Park area, the statement pointed to a 2014 culvert retrofit in partnership with Parks Canada on Sewell’s Road (north of The Toronto Zoo) that allowed frogs, amphibians and other aquatic species to move through the area.

The spokesperson said the City of Toronto is in the middle of updating its maps of wildlife crossing areas, which will allow staff to “incorporate eco-passages/culverts where appropriate during road reconstruction projects.”