Beavers are expanding into the Arctic. These expert dam-builders typically inhabit waterways in boreal and temperate regions of North America. Over the past few decades, however, they have inched into the Yukon, Northwest Territories, Nunavut, northern Quebec, and Alaska.

Beavers feed on bark and twigs. They build their dams out of sticks and branches. Why would these iconic lumberjacks move north of the treeline? Scientists suspect climate change and the fur trade may have played a role.