On first glance, it might look like the beaver is eating the bark off this fallen cottonwood. But they don’t eat this old, dry bark. The beaver is eating the cambium layer, which is the thin layer of new wood just under the bark. In fact, you can see the beaver pick the bark off of the strip of cambium before eating it. The cambium is the active layer of wood that grew this season. Basically, it is this year’s ring added to the tree; the growing part of the tree trunk. It is often called the inn