A few years ago I read Coyote America, by Dan Flores. A large portion of this book is dedicated to Wildlife Services efforts to cull the Coyote. They've been fantastically unsuccessful in this effort, most likely due to behavioral quirk of the species. Coyotes can identify specific individuals by voice, and if one of those voices disappears from the nightly call it causes the females to enter estrus and breed. So if you kill a Coyote multiple more Coyotes literally spring up in their place.