Wednesday, May 11, 2011

Living in a tree house

Nature Watch,

By Susan Thurn,
Cable Natural History Museum

I live in a tree. It is a cedar tree, in fact. I woke up a few nights ago in the middle of my night’s sleep to a scratching noise. After further inspection, I noticed a sound coming from the outer bark of our comfy treehouse. I popped my head out of the main cavity, and was surprised to see a flying squirrel scurrying away. I looked at the side of the tree, and the flying squirrel had been chewing right on our bark!

This treehouse of ours is a bit more square than others. It is, of course, our house rather than a living tree. Imagine my consternation to discover a flying squirrel was chewing away at its cedar exterior. Was it trying to create a nesting cavity in our house?

It turns out that North American flying squirrels use many different types of nests. They have day-time sites to den in which scientists call refugia nests. Their natal nests are used to raise young. During the winter months they live together in aggregate nests, in which large numbers of family and non-family members reside.

The materials flying squirrels use in these nests depend upon what is available. However, in a study done in Canada, almost all of the flying squirrel nests found had strips of white cedar bark within them. Flying squirrels also use moss, lichens, animal fur, bird feathers, leaves and twigs, or even human-made materials such as newspaper or insulation.

The cedar that built our square, A-frame house does not just make good housing materials. Flying squirrels apparently have discovered that there are other benefits of having cedar in their nests. The white cedar bark and wood has insecticidal and water repellent oils.

There are just a few more things worth saying about flying squirrels. Not true fliers, they actually glide using a fold of skin that goes from their front wrist to their hind ankle. They glide up to 120 feet, able to change speed and direction just with movement of their arms and legs. Their fluffy squirrel tail stabilizes them in flight.

Flying squirrels forage for food at night with their keen sense of smell. They will eat plant seeds, leaves, nuts, sap, bulbs, roots, flowers, or bark. More specifically, they will eat mountain ash, juneberry, pin cherry, hazelnut, balsam, and maple seeds. They also will eat fungi or bird eggs, worms, or other small animals. During late winter they will even eat the buds of trees as food becomes scarce.

The siding of our “treehouse” looks a little funny now, with chew marks and scratches in several places, but nothing a little stain wouldn’t hide. Although I am happy that perhaps this flying squirrel isn’t trying to chew a cavity through our house, I also feel lucky to live in the north woods. Flying squirrels are just another animal species to enjoy in our own back yards.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, The Joy of Birds: Feathers in Focus opens in May, 2011. Find us on the web at to learn more about our exhibits and programs. Also discover us on the web at, on Facebook, or at our blogspot, to learn more about our exhibits and programs.

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