Fraser Valley Conservancy worked with cement manufacturer Lafarge to create an innovative concrete tunnel for amphibian protection.
Since 2008, the Fraser Valley Conservancy has been working with local landowners in the Ryder Lake area of Chilliwack, B.C. to study migration patterns of local amphibians. There are six species in the area, including Western toads, Northern Red-legged frogs, Pacific Chorus frogs, Northwestern salamanders, long-toed salamanders, and rough-skinned newts. Both the Western toad and Red-legged frog are considered ‘species at risk’ due to habitat loss and population decline. They tracked when and where the amphibians crossed roads while moving between their forest habitats to their breeding wetlands.
According to Joanne Nielson, executive director of Fraser Valley, adult amphibians migrate on rainy nights in the spring to get to their breeding site and then move back across the roads (again at night) after they have laid their eggs. She says adult migration is not as noticeable due to the timing and lower numbers, but their surveys indicate high numbers of mortality on the roads surrounding the wetland. Toadlets migrate by the thousands during the day for 10 to 14 days in July. The vehicular impact is much more noticeable with them.
The study caught the attention of Lafarge because it aligns with the company’s community investment pillars of education, environment, and sustainable construction. The company donated materials and workers volunteered their time to work on the project. The workers spent four days in July installing a tunnel under the road and rebuilding the road for traffic. This provides a safe travel passage for amphibians, which were perishing on the road in mass numbers.
The innovative design for the concrete tunnel allows light into the space while assuring structural integrity was used. Past studies have shown amphibians will not use a crossing if it is too dark, so the workers cast a manhole-type grate system to allow light through.
“Our partnership with Lafarge has enabled us to finally implement this ‘toad tunnel’ which has been a vision for the conservancy for many years,” said Nielson.
There are other amphibian crossing structures on Vancouver Island and in the Kootenays, however Nielson says the ‘windows’ installed in their tunnel have not been attempted in other structures in B.C., to the best of her knowledge.