A couple weeks ago I wrote a post about sitting and watching the behavior of a beaver on one of the lakes here, and I included this photo of the section of shoreline where it was piling up branches.
Over the weekend I was back at that spot to flip rocks for International Rock Flipping Day, so I checked on the beaver’s progress and took another photo of the same site.
Less a haphazard pile of sticks, more a beaver lodge taking shape. You can see that the beaver in question is working on taking apart the big fallen birch tree. Also, note how the big log running parallel to the shore, near the bottom of the photos, has been almost completely covered over by a thatch of smaller branches in the second photo. Eventually the beaver will cover the lodge with mud, which will freeze solid when cold weather sets in.
Beavers don’t hibernate, but since the entrances to their lodges are below the water level, once the lakes freeze over they’re iced in. They stockpile food ahead of time, dial down their metabolism so that they don’t need to eat as much, and spend the winter in their lodges and swimming underneath the ice. Lodges are generally built with a small hole to allow for ventilation.
I’ll be keeping an eye on this particular lodge this fall and winter, and if anything interesting happens I’ll post more photos. For more information on how beavers and lots of other Northwoods creatures survive the winter, check out the excellent book Winter World by Bernd Heinrich.