Studies in the U.K. and Oz show that there is a dominant male in each of the cat colonies.
He's the one who can beat the snot out of the upstarts, so the colony gets his genes to pass on. Until there's one bigger and badder enough to beat the snot out of the dominant male.
So the get bigger, and nastier.
An emerging technology of dealing with feral cats is to catch the Tom, and neuter him. He's still the dominant male, and gets all the action, but doesn't pass on his genes, or let the females have kttens. Apparently works pretty well.