In much of the BP's natural range (which is vast, btw) most of their natural predators have been driven off either by over-hunting or by habitat destruction. Far fewer predators for BP's means even more BP's than there used to be. Plus, as Brad pointed out, they adapt extremely well to agricultural encroachment. And I'm pretty sure there are still huge areas of their range that aren't harvested at all.

EDIT: I typed too slow on that one.