Road Mortality

Roads pose a major threat to many reptile and amphibian (collectively called “herps”) populations. Animals, including herps, need to access different resources available in different parts of their habitat depending on their age and the time of the year. When roads go through the habitat, they separate animals from these resources and from other individuals, causing habitat fragmentation. This forces animals to cross the road to try and reach these other resources, leading to wildlife-vehicle collisions. This is especially true in southern Ontario, as it has the greatest density of people in Ontario (leading to increased traffic) and roads. Did you know in southern Ontario you cannot travel more than 1.5 km in a straight line without hitting a road? This increases the risk of vehicle collisions for urban herps.

Compared to other animals such as birds and mammals, herps especially are at risk of vehicle collisions. Amphibians, such as frogs and salamanders, are slow-moving and may cross roads when dispersing from their natal ponds (the ponds where they were born) to other habitats. Snakes use roads as a heat source to bask (warm their bodies by laying in a warm, sunny place) and cross roads to reach nesting or hibernacula (overwintering) sites. They also respond to incoming cars by stopping. Turtles travel to find mates, nesting sites, and overwintering sites, and sometimes nest on the side of the road. Snapping turtles will jump when threatened, so will hit the underside of cars if people try to drive over them. Road mortality is especially harmful for turtle populations, as turtles have a low chance of surviving to adulthood. Once turtles reach adulthood, it is crucial that they survive and continue to reproduce – the death of even a small number of adults can lead to population declines.

To better understand road mortality threats to urban herps, the Adopt-A-Pond team has been collecting road mortality data on roads near the Toronto Zoo. The Ontario Road Ecology Group (OREG) first surveyed these roads in 2010 and 2011 and Adopt-A-Pond has continued these surveys since 2017. Our road mortality surveys take place along stretches of road near wetlands and green spaces. When a deceased animal is found on the road or the shoulder, its precise location is recorded, along with weather conditions (like precipitation and air temperature) and habitat information (such as if it’s close to a wetland or train tracks). We use this data to identify areas where there are high numbers of animals crossing the roads, called “mortality hotspots”, and to model the factors that influence where and when animals decide to cross. These results tell us the best places to focus mitigation efforts. You can help collect data on crossing turtles and frogs through Adopt-A-Pond’s Turtle Tally and FrogWatch Community Science programs. This data is shared with interested parties across Ontario to inform mitigation projects, meaning your contributions are helping to prevent future road mortality!

After identifying road mortality hotspots near the Toronto Zoo, Adopt-A-Pond received funding from the Species at Risk Stewardship Fund (formerly managed by the Ontario Ministry of Natural Resources and Forestry, now by the Ontario Ministry of the Environment, Conservation, and Parks) in 2018 to start a mitigation project. With partners including Parks Canada, City of Pickering, Toronto and Region Conservation Authority (TRCA), and University of Toronto Scarborough (UTSC), we installed fencing to prevent small- and medium-sized animals from crossing the road. The fencing was installed on both sides of the road and connected to a concrete culvert. The fencing allows the culvert to act as an “ecopassage”, which means a tunnel or bridge that allows wildlife to safely cross a road or a similar hazard.