Radosz Klecha
Radosz Klecha voted up HappyTwo BeHereTwo's answer

Fights over territory, for mating and/or food competition.  

A male will sometimes try to kill the kittens of another tom, in order to "claim" the mother.  In order to protect her young, she may fight him to the point it gets lethal.

Sometimes the problem is septicemia from fight wounds.  Although the initial wounds aren't fatal, the … Read more