Thursday, October 8, 2009

Do Beavers Eat Wood?

Trick question - it depends on what your definition of wood is. Let's take an aspen branch for example. The beavers absolutely love the leaves, small twigs, and bark. But as soon as the twigs get to the diameter of a baby pinky finger the beaver starts to peel the bark off, leaving the white twig behind, as shown in the 2nd photo. So the answer is more or less no, they don't eat wood. This makes sense when one looks at what food value wood has to a beaver. The wood is mostly indigestible cellulose bound together with lignin. Great fare if you're a termite, but not so much if you're a beaver who has trouble digesting cellulose.

Are the leaves, twigs, and bark much better? Well yes they are. They contain most of the nutrients in the aspen branch and there is much less cellulose. Probably they taste better too, at least to a beaver. A beaver's stomach has lots of bacteria that help to digest their food but even so it's a tough job to digest coarse plant material. The first time through the digestive system produces a soft pellet which the beaver eats. A second digestion pass extracts more nutrients before the final pellet is produced.

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