Frogs, toads and salamanders have no business living in the Yukon. They're amphibians, after all -- animals that rely on the outside temperature to keep their bodies warm. It doesn't seem reasonable to look for them in a place where temperatures regularly drop 30 or 40 degrees below freezing.

Nevertheless, several species of amphibians not only survive, but appear to thrive in the Yukon and surrounding areas. They are the subject of a new brochure funded by Environment Canada and the Yukon Department of Renewable Resources.

Frogs, Toads & Salamanders: Amphibians of the Yukon and Northern British Columbia was researched and written by Lee Mennell and Brian Slough, two Yukoners with a special interest in amphibians and their place in the northern ecosystem.

Slough says the brochure has two purposes: to give people a quick summary of the information currently available about amphibians in the Yukon, and to solicit new information. Sightings submitted by interested observers will add to our understanding of Yukon amphibians, and might add more species to the Yukon list.

"We should know what we have here, in terms of biodiversity," he says. Biodiversity, the rich mix of organisms that makes up a healthy ecosystem, is what got Slough interested in relatively obscure animals like amphibians in the first place.

The most common amphibian in the Yukon, he says, is the wood frog. Wood frogs occur through most of the Territory as far north as Old Crow Flats, living in forests, meadows, muskeg, and even tundra. In fact, they live further north than any other amphibian in North America.

"In the good breeding ponds, they're very plentiful," says Slough.

They cope well with northern conditions. The short summer gives them very little time to go through their development cycle, but wood frogs have adapted by achieving the fastest development rate of any North American frog. The earliest they can breed is late April and by early September they must start looking for a hibernation site, so the young make the transformation from egg through tadpole to adult frog in seven to twelve weeks.

How they survive the winter is still something of a mystery. About 15 years ago, a biologist in Minnesota discovered that wood frogs can survive freezing temperatures. The frogs' cells fill with glucose as the temperature drops, and the glucose acts like antifreeze, preventing the cells from freezing and rupturing, even when the frog's body temperature falls several degrees below zero.

As far as researchers can tell, even with its own personal brand of antifreeze, the wood frog can survive temperatures no lower than minus six or seven degrees Celsius. In the Yukon, maintaining a temperature above minus six for the entire winter requires insulation.

Slough says the frogs seem to find enough insulation by burrowing under the leaf litter in the forest: "They don't even dig into the ground."

Other amphibians living in the Yukon are less tolerant of cold and need more insulation. The boreal toad and spotted frog are found in high-snow areas in the southern Yukon, where the extra insulation provided by the deep snow helps them survive.

The southeast Yukon, along the La Biche River, is home to an even less common Yukon amphibian, the boreal chorus frog. It is at the northern edge of its range, but it manages to survive in the shelter of the La Biche Valley's moist old-growth forest.

The Yukon might be home to more amphibians that have simply gone unnoticed because no one was looking for them. Now Lee Mennell and Brian Slough are looking for them, and they are enlisting the help of anyone interested enough to pick up their brochure.

The brochure lists several animals to watch out for, species that have not yet been sighted in the Yukon but are known to survive in similar climates. They include the rough-skinned newt, the northwestern salamander, the tailed frog, and one reptile, the red-sided garter snake.

The hunt for amphibians is all the more important because amphibian numbers appear to be on the decline around the world, says Slough. Reasons for the decline vary, depending on the place and the species, but most are related to environmental change, including changes brought on by human activity.

For more information about Yukon amphibians, look for the free brochure Frogs, Toads and Salamanders, or contact the Canadian Wildlife Service, Environment Canada, in Whitehorse.