First off; beavers are near deep water 90% of the time allowing you to water-stomp then or if you really hate that you can simple side-step; or you can use ANY obstruction such as a tree, log, or pile of logs! The beavers dont actually aim directly at you so its fairly easy to avoid.
Deers "RAM" is WAYYYY worse in which i've had deers "Triple-RAM" me in which if your walking they Ram-Ram-Ram with at most a 0.5 second delay; god knows they can do a Qaudra ram, but getting 40 HP is a bit of a hassel for me!
I try to use the tree tactic with deer but they dont attack much unless you attack in which 70% of their attacks are rams (they still ram when only 2 squares away so distance doesnt seem to play TOO much of a roll).
Bears can basically shoot at your (BB drain) so just accept the combat is not easy.