This year has been a great beaver year at Bearskin, with at least four beavers working the shoreline daily. All summer guests have reported being fascinated by sitting on their docks and watching beavers scurry back and forth across the bay. Our staff member Lionel says that he often sees them visit the staff dock as they clear nearby alders, and Bob recently came across a downed tree in front of one of the cabins.
Of course, sometimes we wish they wouldn’t do so much landscaping, but beavers are fun to watch, and their engineering work can be highly beneficial to the ecosystem. Did you know that beavers actually help prevent forest fires? And here Smokey the Bear is getting all the credit.
Once nearly hunted to extinction, beavers now live in every county in Minnesota, but we have a lot more of them up here than in the rest of the state. Keep reading to learn about the life of a beaver in northern Minnesota and how their busy beaver ways impact the environment.
Aquatic adaptations
The beaver is the largest rodent in North America (beavers are second only to capybaras globally), weighing about 40-50 pounds on average. Since they spend so much of their life in the water, beavers have a number of adaptations that make them perfectly suited to the life aquatic, including:
- Beaver fur is insulating against the cold, with a dense underlayer that traps body heat and outer guard hairs that block water. They secrete castoreum, an oily substance, for waterproofing.
- Their tails act as a rudder when they swim.
- Their eyes are covered by transparent inner eyelids (called nictitating membranes) that protect their eyes underwater while allowing them to see clearly – kind of like goggles.
- They have muscular valves in their ears and nostrils that seal when they dive. They can also press their tongue to the back of their throat allowing them to open their mouth and carry sticks while underwater.
- Like birds, beavers have a cloaca – a single opening for their reproductive, urinary, and digestive tracts. Scientists believe this might be to protect them from infection in the water.
- Beavers can stay underwater for around 20 minutes.When they come up to breathe, they can replace 75% of the air in their lungs with just one breath. We can only take in about 15%!
The life of a beaver
Beavers are herbivores, and during the spring and summer they like to eat plant material including leaves, roots, grasses, sedges, aquatic plants and more. During the fall and winter, they eat more bark and cambium (the layer of tissue between the bark and wood). They enjoy a lot of trees that we have up here in abundance, like aspen, alder, and birch. Like all rodents, their incisors constantly grow, so they have to keep chewing on wood to keep their teeth the right size.
Beavers are nocturnal and crepuscular (meaning they’re active at dawn and dusk), so they spend most of the daylight hours at home in bed.
The most famous aspect of beaver life is that they build lodges and dams. The lodge is the beaver’s home. The entrances are underwater, preventing predators like wolves or bobcats from coming inside. (Many people don’t realize that wolves are the greatest natural predator of beavers in this area, after humans.)
Beaver dams slow the flow of water to create deep ponds around the lodge. Typical dams range from 10 or 15 feet to a few hundred feet long, with the world’s largest beaver dam in Alberta measuring 2,790 feet.There’s a huge beaver dam that often blocks the entrance to mowing the ski trails from Clearwater Road that occasionally attempts to be competitive with the size of that Alberta dam! There’s also a very serious dam near campsite 22 in the East Bearskin Lake USFS campground. Many of our ski trails regularly suffer from excess water due to the engineering feats of beavers.
How beavers survive in winter
Beavers don’t hibernate, but they do hunker down for winter. Beaver lodges have a dry room that remains above the water. It’s insulated with sticks and mud and stays pretty warm compared to the outside air. A typical lodge has 5 or 6 beavers, including the parents, kits, and yearlings, they can huddle together for warmth. Sometimes they’re even joined by muskrats – the more body heat the merrier!
Lots of prep work goes into surviving the winter. Lodges have an underwater cache of tree branches for food, which the beavers stick into the muddy bottom of the pond. The timing of creating this cache is critical – too early and the wood could rot, too late and they may not store enough to last all winter.
Beaver lodges are dark inside, and one interesting fact is that beavers stop following a 24-hour day in the winter and instead follow a slightly longer cycle, sometimes up to 29 hours.
Mating takes place in late winter under the ice. In spring, females give birth to a litter of 2 to 4 kits in the beaver lodge. Kits are born fully furred and learn to swim within days. Sometimes you can hear beaver babies squeaking when you are near a lodge.
The impact of beaver engineers
The Minnesota DNR website calls beavers “nature’s original water conservationist and land and wildlife manager.” Beaver ponds have incredible biodiversity, possibly more than any ecosystem in the forest.
Beaver engineering even improves water quality. Rainwater runoff can wash toxins into waterways, but a beaver dam traps sediments, heavy metals, and excess nutrients like nitrogen and phosphorus, filtering them out of the water.
This year we’ve all heard a lot about wildfires. Wetlands made by beavers concentrate water and moisturize the landscape, mitigating the spread of fire. These wetlands can also become a shelter for other wildlife trying to escape the flames.
You can easily observe an example of changes created by beaver dams on the Gunflint Trail about half a mile after our East Bearskin Road entrance on the east side of the Trail. A small, circular beaver pond existed in that spot for years, often photographed with moose standing in it.The pond was created by a dam that’s easily visible from the Trail. When the snow melted in spring 2026, the dam was clearly broken, and nothing but black mud remained in the former pond. Our home is not far from that dam, and for some mysterious reason this spring we suddenly had Gooseberry Falls on the west side of our property. Now we realize it was the water draining from that pond after the dam was breached. If you’re a regular visitor to our area, watch that pond over time. We do know the dam broke decades ago (there’s a story), but eventually it must have been rebuilt, as there’s been a pond in that spot for as long as we can remember. Will the beavers rebuild? Or is it destined to be a low muddy or grassy spot forever after? Watch to see what happens.
Beavers at Bearskin
Historically, the best time to see beavers at Bearskin has been May, but they’re – dare we say – busy all summer. Now and then you can even see them when there’s snow on the ground, like the industrious beaver in the video below who decided to get to work on a mild day in January.
