Beavers on the tundra? Yukon biologists see the unexpected

Flying over the tundra onYukon's vast north slope in 2015, government biologist Tom Jung looked out his window and dida double take.

He and fellow biologist Dave Mossop were looking for peregrine falcons as part of a monitoring program, but Jung spotted something different, and unexpected a beaver dam, on the Babbage River in Ivvavik National Park.

"I said, 'hey Dave, have you ever seen a beaver dam?' Because I thought it was a little odd," Jung recalled. "He had said he hadn't, so that got me thinking that this was a bit of a unique observation."

The two biologists helped co-author a report recentlypublished in the journal The Canadian Field-Naturalist,about what they saw.

It turns out, their observationsweren't completely uniqueInuvialuit hunters first reported seeing beavers in the area a decade ago.

But such sightings are a relatively new phenomenon.

'Shrubification' and climate change

Beavers have a vast range across North America, but are not typically seen on the treeless tundra. The damspotted by Jung and Mossopwas made withshrubs.

"Beavers arequite adaptable and they can use different materials to make dams," Jung said. "We haveseen, inthe Yukon, them using rocks to build their dams, and other things."

The biologists aren't sure how or why the beavers have moved into the area, but they say Yukon's coastal plainis seeing more"shrubification", a consequence of climate change in the Arctic.

"Beavers are what we call a 'keystone species'they're one of those species that can modify habitats for other species," Jung said.

He says beavers on the coastal plain could have an impact on other species, by damming rivers that fish use to spawn.

"In the natural world, change is good for some species and not so good for other species," he said.