One is about a grizzly bear and about his life. In it there is an escaped circus bear that tries to take over his territory. It also talks about how he lost his mother to poachers?

The other book title I'm looking for is about a black beaver and about his life. How he finds a mate and raises a family and the sickness that comes and nearly kills everything?

I would be greatly appreciative if anyone could tell me the titles for these books, I read them in elementary school and enjoyed them a lot!