What you are saying refers to the term anthropomorphism, the attributing of human characteristics to animals. It doesn't really make sense to do this because we cannot get into the minds of these creatures. For the taking of a life to be deemed murder there must be premeditation. Perhaps I should have clarified my original statement to use this term instead of the term "kill"
Since their (animals) primary motivating force is instinct, it is probably safe to say they are driven to acts of violence by reasons other then sheer pleasure. I don't believe there is an element of premeditation in what they do