The same term is used for cattle. I guess species at the top of the food chain choose the terms of art. I wouldn't be surprised, though, to learn that the monkeys have their own sound/ utterance to mean the killing of people.
He means “cull” is a term we use for killing cattle.
That's not precisely correct. With respect to cattle or any other domesticated ungulates, "culling" means removing from the herd. That might occasionally be slaughter, but usually means selling the animal. Of course the new owner might buy the animal in order to slaughter it, but we can't assume that.