It’s no secret that transportation corridors in the biosphere pose a significant threat to wildlife. Roads and railways cut through important habitats across eastern Georgian Bay, forcing wildlife to make dangerous crossings in order to carry out daily and seasonal movements. Furthermore, female turtles are often attracted to gravel road shoulders to lay their eggs, putting them and their offspring at risk of being hit by vehicles or their nests being raided by predators. Similarly, snakes are attracted to the warmth of roads and are often hit by vehicles while basking.
Physical barriers are needed to prevent wildlife from going on roads and instead direct them to crossing structures that they can use to safely pass over or under a road. However, not all fences and crossing structures are created equal, and different species require different design specifications to keep them off of roads. Similarly, what works in some areas of Ontario may not work here in the Biosphere region, due to differences in landscape features. Thus, it is important to develop designs and best management practices that are specific to this region.
In the Township of Carling, a novel fence design is being piloted in an area identified as a reptile road mortality hotspot. In the fall of 2022, the Georgian Bay Biosphere (GBB) and Township of Carling installed a 240 metre concave fence along a township road where it bisects a wetland. The concave fence is intended to lead reptiles and other wildlife, including fish, to four culverts (three aquatic, one terrestrial) that will act as safe eco-passages, connecting both sides of the wetland underneath the road.
Large-bodied species such as eastern foxsnake, Massasauga rattlesnake, snapping turtle, and Blanding’s turtle are the target species for this pilot project. With this in mind, the fence design had to take into account the fact that foxsnakes, a threatened species, are excellent climbers. Provincial guidelines state that fencing for foxsnakes must be a minimum of 2 meters in height, with an overhang. However, a smooth, curved (concave) fence design might pose a greater challenge to climbing foxsnakes and therefore allow for a shorter fence height (i.e., less than the recommended 2 m).
In addition to considering species’ needs, other important factors influencing the final fence design included road terrain, road maintenance, seasons/weather, potential for yearly maintenance, long-term maintenance, and aesthetics. The Township of Carling Public Works department preferred a design that placed the fence at-grade so that it would not impede or be destroyed by road maintenance (e.g., grading, snow plowing). Additionally, discussions with local First Nations highlighted the need for a design that would not impede access to land and hunting grounds.
Studying how this novel fence design functions in practice is critical. GBB is assessing maintenance needs, structural durability, and performance of the structure over time, including the effects of freeze-thaw cycles and public works activities. In addition, beginning in spring 2023, Sabrina Lounsbury, a graduate student from Laurentian University has been working with GBB on evaluating design effectiveness. Sabrina’s research will:
- Compare road mortality of snakes and turtles pre- and post-mitigation to determine if the fence has reduced mortality along the previously identified hotspot;
- Conduct controlled behavioural studies to determine how snake and turtle species interact with the fence and fence ends; and
- Investigate the willingness of reptiles and other animals to use culverts within the fence as eco-passages.
The findings from Sabrina’s research will provide insights into how this fence design may be improved and how the same or similar designs can be used in other areas, including other parts of Ontario, Canada, and the United States. These types of pilot projects and research studies are extremely important to advancing approaches to reducing threats to species at risk in the biosphere and beyond. Stay tuned for updates on Sabrina’s findings!
This research was funded by Environment and Climate Change Canada, Ministry of Environment, Conservation and Parks, and Ganawenim Meshkiki. GBB is grateful to all project partners and supporters including: Township of Carling, Laurentian University, Killbear Provincial Park, Wasauksing First Nation, and Shawanaga First Nation.
For further reading on this project, and to learn more about how you can help snakes and turtles in the biosphere, check out the following articles and be sure to report your sightings on GBB’s iNaturalist project!
