if you see a beaver dam and wanting what's the loot don't go near it because any nearby beavers would aggro on you even though it's temperament are "friendly" you probably didn't read the description of the friendly temperament

here's the description:

Friendly creatures will act in a similar manner to Docile creatures, however, if provoked, they may either fight or flee depending on the creature.

More Castoroides Encountering Tips