EDMONTON JOURNAL (Alberta) 14 May 05 The toads less travelled: U of A researcher tracks haunts of at-risk species (Jodie Sinnema)
Edmonton: Connie Browne tracked Oscar the Western toad last summer to his home in an old tractor oil filter, where he dined on bugs hovering over a junk pile in a field.
She found Ross the toad hibernating in a muskrat tunnel in Elk Island National Park with 13 roommates. Slimer was hanging out in a pile of algae. Aspen was packing on weight for her winter rest in a red squirrel midden by feasting on ants scurrying along a rotten birch log.
This summer, Browne hopes to track many more warty-looking Western and Canadian toads like Oscar, Ross, Slimer and Aspen, by strapping tiny waterproof radio transmitters to their back legs to chart their habitat and why the two species are in decline.
"We need to figure out what essential habitat features are necessary to keep these species in these areas," said the 25-year-old PhD student in biological sciences at the University of Alberta. "The toads are two species at risk. They are just one of those species that aren't so tolerant to change, but they are a really important part of the food chain."
Not only do they eat grasshoppers and other pests, they are food for coyotes, ravens and raccoons -- although the predators have learned not to eat the toxic skin from the toads' backs.
Browne said the Western toad has disappeared from more than 50 per cent of its range from Alaska to the southern United States in the last 10 years, though it seems to be doing fairly well in Alberta.
"It's the only species in Canada that is considered internationally to be endangered by the World Conservation Union," she said. As for the Canadian toad, Browne wasn't able to find a single one in Elk Island park in 2003 or 2004.
While there may be a few rare Canadian toads still hopping around the park, Browne said, they could be extinct locally. She hopes her work this summer near Lac La Biche, 220 kilometres northeast of Edmonton, will help explain what's happening.
Browne has spent the last week walking around ponds near the Heart Lake reserve like a five-year-old searching for leaping friends. She hasn't seen any toads so far, since there was still frost in the ground, but hopes to track 12 of each species, following them from May until October, when they start their hibernation. When Browne catches them, she will strap on a one-gram radio transmitter and antenna -- a fraction of the average Western toad's weight of 20 grams -- around their back legs, using soft medical tubing as a belt.
Browne can then track the amphibians from up to one kilometre away, recording where they like to breed, their preferred habitat and where they spend winters. She wants to find out how human development may be playing into habitat loss or alteration.
The toads generally like to breed at the shallow end of ponds. During her 2004 study of 32 toads in Elk Island park, Browne discovered the toads moved from the tall sages and grasses along pond shores into aspen forests or black spruce bogs once their eggs were laid. She also found seven who laid eggs in a pasture spotted with ponds. Five of those then leapt away to live in nearby alfalfa, wheat, oat or barley fields.
Farmers' fields "could be a good place for them to forage, lots of bugs and invertebrates in there, but ... a lot of them were being killed in the fields."
Oscar, named after the Sesame Street character who lived in a garbage bin, fared well, considering he hunkered down in a junk heap.
"It seems kind of sad for a toad to be living in an old oil filter, but I think (the filter) was old enough that it wasn't really hurting him," Browne said.
Aspen had a routine, staying in her ant-laden birch log for about one month, then leaving, only to return in the fall to the exact same spot. "She really knew her landscape. She was picking certain habitats. She wasn't randomly moving."
Browne is concerned for amphibians in general, since 19 out of the 33 species of amphibians in Canada -- toads, frogs, salamanders, newts -- are at risk.
"They are almost all because of human-related causes," she said.