Beaver Preparations for Winter - UPDATE October 19, 2020

New Beaver Lodge on 10-4-20New beaver lodge on 10/4/20 Beaver lodge finished on 10-19-20New beaver lodge finished on 10/19/20

On this 31°F day with no wind, it was time for Donna and me to paddle across the lake to see how the beavers were progressing in their preparations for winter. We especially wanted to see how they were coming on their new lodge that we had checked 15 days ago. At that time, it was a lot of bare sticks piled on the beginnings of a lodge against the shoreline with some of the mudding done. Today, it had a whole different look . The sticks are sealed in place with a lot of insulative mud and aquatic vegetation place between them and on them. Their new lodge of 2020 has the finished look we expect this time of year.

New Beaver Lodge with Food CacheNew beaver lodge with food cache - 10/19/20

They had also greatly expanded their winter food cache that is made up of aspen, birch, and shrubs (alder and willow?). The freshly cut end of an aspen sapling that was sticking out toward the camera shows their tooth marks.

Throughout the winter, the beavers will swim out underwater, nip off branches, bring them inside, and ingest the thin bark and underlying cambium—but not the wood. Microorganisms in their intestines digest only about 30% of the cambium’s cellulose on the first go-round, so they eat their fecal pellets and extract more nutrients by running them through again.

Beaver Lodge of 1977Beaver lodge of 1977 - 10/19/20

We then paddled less than a hundred yards up the shoreline to see what they might be doing with their 43-year-old lodge that was built back in 1977. They had created paths in the snow as they headed up to the top to focus their attention on the vent hole. I didn’t want to step on the lodge, so I didn’t learn what they exactly were doing. There was no winter food cache, so they are not planning on spending a lot of time in this lodge.

Beaver and Mink tracks on Lodge of 1977Beaver and mink tracks on lodge of 1977 - 10/19/20 Beaver Lodge of 1977 Vent AreaVent area on beaver lodge of 1977 - 10/19/20

The lodge also had a set of mink tracks in the snow, so I began putting out bologna, hoping to see minks that I recognize. I’m not expecting to see gray foxes this winter as enriched a couple of recent winters. I don’t know what happened to them. Before 2007, I never saw any—only red foxes. Then we saw about equal numbers of reds and grays for a decade—and suddenly no grays.

After several years of seeing woodchucks raising young in burrows under the buildings here, I haven’t seen any for several months now. Things mysteriously change, leaving me wondering with no clues.

Thank you for all you do.
Lynn Rogers, Biologist, Wildlife Research Institute and North American Bear Center