I went mountain biking with Bill Nelson along the Minnesota River bottoms this week and he showed me an area just east of Cedar Ave. where beavers have been gnawing away at a dozen or more large trees.
The Wikipedia entry for beaver says:
Beavers fell trees for several reasons. They fell large mature trees, usually in strategic locations, to form the basis of a dam, but European beavers tend to use small diameter (<10 cm) trees for this purpose. Beavers fell small trees, especially young second-growth trees, for food.
But it’s puzzling because the trees above are not in place where the logs could be used to "form the basis of a dam" and they’re much too large for beavers to move.
So Bill and I have a formulated a theory: it’s a training facility. Prove us wrong if you dare.
I stumbled on beaver island on a night ride this winter. it’s amazing how many big trees they’ve taken down. there’s a lot of unfinished work though.
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This is fascinating. I’ve seen where small trees have been cut down in the Lower Arb. Most have been dragged to the river. I assume that these beaver have constructed their dwellings in the banks of the river.
I think I recall that the beaver may be cutting down larger trees that block out sunlight that keeps the forest floor from growing more edibles. The gnawing also helps to keep their teeth and jaw strong, and there may be some nutrition in it for them as well. Of course, the dying tree will serve to feed the other trees eventually, and it’s all part of the circle of life. The beaver I think really responds to the amount of light available. It is highly possible that the beaver does not know whether or not a tree is too big to fell in one or two gnawings and he or she just moves on after awhile for more immediate gratification.