I saw somewhere in this thread somebody mention that some species become over populated. IMO there isn't much truth to that. What we have is too much human expansion. That is, the the animals were there first, at least before European's arrived. If you live in Florida, you should expect gators, and if you live in Texas you should expect snakes. The snake didn't ask for the housing development to encroach into its territory, so why should it be killed of relocated? Even in the midwest where the deer are over populated, what really happened is that every natural pretador of the deer was exterminated by humans, so their populations boomed, so we had play the role of the wolf/bear/etc and kill them to keep them in check. Look at yellowstone and wolf-elk relationships.
If you kill something, eat it, use it, and you become part of the ecosystem, otherwise you're a vagabond. I do not know of any single non-human animal in nature that just goes around looking at other animals. You either eat or be eaten.
Animal Planet - Suprisingly inHumane