Like cynthia said. Prey animals reproduced in litters and the predators aren't around much any more. For example rabbits. We have millions of them and nothing to keep them under control. So got a dog and he seems to help and just got a cat and I'm going to keep it outside to help keep them away or if he's luck he might catch a few. But for the few hundred that continue to invade my space and garden I've pulled out my old Dasiy BB gun and I'll be on the hunt.