> If you have an actual sound ecosystem, in a sufficiently large habitat area (not encroached by humans, roads, etc.), culling is rarely necessary.

It's really a question of the extent to which humans get bothered when prey populations get too big and then they leave the preserve and start getting hit by cars. Or too many wolves and they start killing farmers' sheep. Culling helps avoid the wild swings in population.

I'd also point out that even with populations that are not in good shape (threatened or declining), selling super expensive hunting licenses can still make sense. If $50,000 = +3 rhinos, let the hunter kill the rhino. Of course there are perverse incentives and all sorts of practical difficulties, but I just want to make the point that it's possible for that sort of thing to be in the best interests of the species being conserved.