Conservationists struggle to protect toadlets
It is one of the greatest, if tiniest, terrestrial migrations in North America, an estimated 100,000 western toadlets making their annual overland trek from the pond of their birth in Chilliwack, across a farm pasture, and into a bordering forest.
The distance is only a two-minute walk for humans. But for the brown toadlets — about the size of your thumbnail — the journey is fraught with dangers. There is the unknown number of invasive bullfrogs lurking in the pond, the field grasses rustling with predatory garter snakes and, worst of all, the fast-moving motor vehicles on two lanes of asphalt in their path.
“It’s sad to see a lot of them get hit because people are driving up and down,” says Sofi Hindmarch, a biologist with Fraser Valley Conservancy. Right on cue, a diesel-spewing pickup truck roars past, in open defiance of conservation measures.
To improve the odds, in 2015, conservationists created a tunnel under Elk View Road in the Ryder Lake area, and put up 350 metres of black plastic fencing in an effort to direct the toadlets towards the tunnel — and safety.
It doesn’t always work. The toadlets can get around the fencing and be squished by motorists who refuse to take a simple voluntary detour on Ryder Lake Road that would avoid the area during the 10-day migration.
“It’s only 400 metres difference,” Hindmarch said. “That turns out to be 24 seconds if you drive 50 km/h.”
Making matters worse, the toadlets seem to prefer to move across the road when it is busiest — sunrise to noon, and early evening to dusk.
The number of toadlets varies from year to year, but 2018 is looking like a good crop — an estimated 100,000-plus, compared with 7,500 in 2017 and 30,000 in 2016. Volunteers will later count toadlets from photographs to obtain a closer estimate.
Western toadlets also occur in the Lower Mainland in Langley township and Mission, but only Ryder Lake has a designated tunnel and systematic monitoring. Funders have included the Habitat Conservation Trust Foundation and the federal government.
The adults arrive in the pond in spring to breed, some returning shortly thereafter to the forest, and others sticking around until the fall, Hindmarch said. Adults tend to leave at night and sporadically, rather in pulses, minimizing highway carnage.
The western toad is a species of special concern in Canada, and has a wide distribution in western North America, from Baja California to Alaska, and from the Pacific coast to Colorado and Alberta. Adult body lengths range from 55 to 145 millimetres.
In addition to motor vehicles, threats include logging, pollution, fungal disease, and climate change. At Ryder Lake, the pond, pasture, and forest are all on private land, highlighting the need for formal protected area status for critical habitat.