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Endangered frogs on Bowen have no road sense
If you’ve driven across the island on a rainy fall night you may be all too familiar with the last minute realization that what you thought was a leaf blowing across your lane is actually a frog, or more likely in most cases, was a frog. During the fall, frogs, newts and salamanders migrate from their shared wetland breeding sites to hibernation areas in the forest or streamside, using established paths year after year and even generation to generation. When roads bisect these paths, they are extremely dangerous because the amphibians have a strong instinct to continue on their set paths, and haven’t developed the ability to sense the danger roads pose to them. Adult amphibians normally have high survival rates, so roads causing a lot of adult deaths have a big negative impact on their populations.
Scientists are very concerned about road mortality in amphibians, says Amanda Kissel, a researcher with the Oregon Spotted Frog Recovery Team. She explains that amphibian conservation is an important issue for everyone since amphibians act as indicator species because of their sensitive skin and their use of both water and land as habitat. What that means is that amphibians can indicate to us humans when there is something going wrong in the water bodies and landscapes they live on, which gives us a chance to do something before people start being affected. Without the frogs and salamanders, we may not detect problems fast enough. According to Dr. Wendy Palen, fresh-water ecologist at Simon Fraser University, amphibian population declines are a hallmark of environmental change around the world.
Here on Bowen Island, we are lucky enough to share our forests and wetlands with the Red-legged Frog, which is receiving a lot of attention as a “Species at Risk”. Its habitat is being lost due to human land use, states the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Our population on Bowen is fortunate to have intact wetlands and forests that have been spared from intensive urban development, agriculture and forestry. However, road mortality is still the leading problem for these frogs, says Palen, and the roads on Bowen still pose a threat. Red-legged Frogs can travel seven kilometers when migrating, and this can mean crossing several roads on 12km long Bowen Island. If you happen to be on foot on our roads in the fall, you’ll notice dozens of flattened amphibians, lots of them with the telltale red-streaked hind legs of the threatened Red-legged Frog.
So what can we do? Well first of all, we can avoid driving during times and through areas of high risk to these frogs. Warm, wet fall evenings are when the frogs are most likely on the move, says Dr. Barb Beasley, coastal ecologist and director of the Association of Wetland Stewards for Barkley and Clayoquot Sounds. She points out that they will mostly be crossing roads close to wetlands. On Bowen, one example would be on Grafton Road where it passes Grafton Lake near the fire station. Some municipalities, such as Chilliwack and Squamish, have even investigated closing portions of road completely during high amphibian risk times. Another easy action would be to increase awareness of the threat roads pose to endangered amphibians by speaking to your friends and neighbours, and pointing out high-risk locations you know about. In some communities, people have become so concerned about their resident amphibians that volunteers build protective fences and carry buckets of at-risk amphibians to safety by hand. For example, Britain’s Toads on Roads program includes 880 migratory crossings with cautionary signage that are monitored nightly by local citizens. On Vancouver Island, a program called the SPLAT amphibian tunnel project has created underground tunnels for amphibians to use at high-risk locations. The project was spearheaded by Dr. Beasley, and serves as a pilot project for amphibian tunnels in other locations. Beasley and her team set up fences to direct amphibians towards the tunnels, then use traps and motion-sensor cameras to record data on usage and monitor their effectiveness. Red-legged and Pacific Tree frogs, as well as Rough-skinned Newts and Northwestern Salamanders all use the tunnels, says Beasley, and all of these species are present on Bowen. Not all communities have the funding for this type of project, but Beasley suggests exploring the use of existing road culverts with temporary fencing to direct frogs and salamanders to cross safely.
For more information or to get involved in conservation efforts, get in touch with the Bowen Nature Club (firstname.lastname@example.org).