Cats! Dog owners must keep their pets on leash and clean up after them. Not so cat owners. They let their animals range free. Cats don't eat the bulbs; but they love to shit on the soft earth and scratch out the bulbs afterwards. Also, maybe deer. I've never observed them browsing on anything but native plants growing at the forest edge, but my neighbor assures me they eat her roses. And someone's been eating my irises.