Coyotes have a unique ability to control litter size based on population levels. When they sing at night females sense population numbers by responses to the singing. When low, their litters can have 20 pups. When high, as few as 4. A federal study at the Savannah River Plant, aka "Bomb Plant" inserted vaginal transmitters into pregnant does. When the fawn dropped, the transmitters activated which allowed the biologists to quickly go to the drop site. More often than not the remains of the fawns were found and DNA testing confirmed coyote presence. 500 coyotes were exterminated in the study site over the course of a year. The following year there was no significant reduction in fawn kills by coyotes. Coyotes survive regardless of efforts to control their population.
