Posted Saturday evening, June 3, 2017.
You knew right away what you were looking at in this photo, right? A beaver dam. And you recognized the river too. The Babbage River in the Yukon. And geography wiz that you are you know that the terrain up thataway is tundra. And, since you’re also up on your mammals, you know that a tundra is a place you’d look to find beavers since beavers like trees for building and food and tundras are relatively treeless. So it’s likely when you looked at the photo and saw a beaver dam on the Babbage River in the Yukon, you did a double-take, just as this wildlife biologist did:
A little over a year ago, Tom Jung, a wildlife biologist with the Yukon Department of Environment, noticed something odd. He was flying in a helicopter over the Beaufort Coastal Plain, an expanse of windswept tundra between the Brooks Range and the Arctic Ocean, with a group of colleagues surveying gyrfalcons and peregrine falcons.
“I had to do a double take,” says Jung. “Sometimes in a wildlife survey, if you don’t see much for a while, you might get a bit googly-eyed.” But it was a beaver dam, on the Babbage River, right where it wasn’t supposed to be.
Beavers are fairly common in the boreal forests of North America and Canada. But because they rely on wood for food and shelter, treeless tundra habitat isn’t somewhere you’d expect to run across one. Jung had never seen one in the area before, nor had any of the other scientists he was with. When he returned from the trip, he learned that local Inuvialuit hunters had spotted dams and lodges on other rivers nearby in 2008 and 2009.
Now, no doubt you’re asking what the beaver are doing and how they’re managing in a terrain where the dominant vegetable life has been sedge, moss, and herbs---tasty grazing for caribou but hardly dam-building material. The answer, of course, is climate change leading to Shrubification. Put simply, it’s warm enough up there now for woody plants to grow. As Rebecca Heisman reports in Sierra Magazine:
Streams and wetlands once devoid of beaver food have become a buffet of willow, birch, and alder…
The presence of beavers is more than just a novelty. Beavers are what ecologists call a keystone species, able to reshape entire ecosystems through their dam building. “Beavers alter streams and the surrounding vegetation—an effect that cascades in all directions. They will provide another food source for Arctic predators and will change stream ecosystems in concert with the climate-induced changes,” says Kent Woodruff, a beaver expert with the U.S. Forest Service. “Fish distribution will respond, and other wildlife and plant species will shift as well.” When a beaver dam turns a fast-flowing stream into a marshy pond, everything from sedges to songbirds are affected.
Moose have been moving in along with beaver. Snowshoe hare too.
The other question you might have or, at any rate, the question I had, was how the beaver got there. The Beaufort Coastal Plain is a long hike---or swim---from the nearest boreal forests. But swim is what they would have done, either following ponds and streams over the mountains or swimming in the ocean up along the coast. The freshwater route seems the more likely, but either way, the first beavers to pioneer their way up there were some adventurous rodents.
You can read all of Heisman’s report by following the link to Say Hi to the Beavers of the Tundra at Sierra.
Top photo by J Fransden courtesy of Canada Parks via Sierra.