September 18, 2009
Toads Croak on Highway 6

toad eyes car before crossing

Efforts Made to Reduce Death Toll As mass migrations go, a very impressive one occurs each August near Summit Lake south of Nakusp in the West Kootenay. Upwards of a million young western toads (Bufo boreas) make their way from the lake-shore breeding area to upland habitat. In their path, however, is busy Highway 6, claiming the lives of thousands. During a two day period an estimated 90,000 dead toadlets were found on a one kilometre stretch of highway. While the problem is not new, biologists from the Fish & Wildlife Compensation Program (FWCP) took action this year in an attempt to improve their chances of survival. "Currently there is some wildlife fencing, covering a portion of their migration path, directing the toadlets to use one of two culverts but both the fence line and the culverts were extremely dry," says FWCP senior wildlife biologist John Krebs. "We sent a team to set up a gravity-fed sprinkling system from a nearby creek in order to thoroughly wet the key areas." The goal was to encourage the amphibians to keep to the wetted areas (to promote culvert use rather than the road), and to reduce the risk of dehydration. In Canada western toads are federally listed as a "special concern" and worldwide (by the International Union for Conservation of Nature) as "near threatened" with a downward population trend. "The importance of the Summit Lake breeding area for western toads cannot be over-stated," added Krebs. "Though once being widespread throughout North America, B.C. is now the continent's stronghold for western toads. The West Kootenay provides some of best habitat for them in the province and within the region the breeding phenomenon at Summit Lake is second to none, by a long shot, – and this is why the FWCP chose to act." The FWCP works on behalf of its program partners the B.C. Ministry of Environment, BC Hydro and Fisheries and Oceans Canada to conserve and enhance fish and wildlife impacted by the construction of BC Hydro dams. "Adult western toads converge in the shallows of Summit Lake to breed in late April," said FWCP co- chair Wayne Stetski. "The emerging tadpoles stay in the warm shallow waters and, in mid summer, metamorphosis occurs and they transform into toadlets. At the end of summer they gather in massive numbers before making their way to upland habitat. It really is an amazing sight!" Globally they are likely a multitude of reasons for the sharp decline in western toads, loss of wetland habitat among them. Studies have shown that the species is also sensitive to environmental stressors such as UV exposure and drought. This recent action by the FWCP should help the situation but more work will likely be needed in the future. Western Toads & Moisture Control:

• Their relatively thick skin helps them retain moisture;
• They have specially designed hind limbs to dig themselves into a hole should they become too dry;
• They have a patch of skin (actually called a "drink patch") on their ventral (under) side which is thinner and helps them absorb moisture directly from the ground;
• Their dorsal (top) side absorbs heat energy and the ventral side helps cool it;
• They tend to forage at night, especially during drier times of the year, only being more active during the day during wet or overcast weather; and
• Touching their skin will not give you warts (but it is extremely distasteful to would-be predators).

Angus Glass
Fish & Wildlife Compensation Program
103-333 Victoria St. Nelson, BC V1L 4K3 Canada
Tel (250) 352-6874 Fax (250) 352-6178
angus.glass@bchydro.com