Although I have seen a beaver (Castor canadensis) only once during the last 15 years or so, I know that they are quite common around here. They leave behind abundant evidence of their activities, including not only the trees they felled but also those whose trunks they gnawed on.
I photographed this young beech last weekend at a spot quite close to my house. The patches of scraped bark are telltale signs of a beaver's feeding activity. Here is a closer look that shows the marks left by the individual teeth.
If I get a chance this weekend I will check up on the same tree to see if it's still standing.
Some of the previous posts featuring beaver activities are here, here and here.