There are evidently three types of dung beetles - rollers, tunnelers and inhabitants. The rollers take the dung away from the pile and bury it somewhere else to munch on later, or have their babies in. That's what this guy is. The tunnelers make a tunnel underneath the dung pile, and the inhabitants just live in the pile.
They like herbivores more than carnivores. Understandable. Evidently, they aren't eating the dung, but the parts of food that get through the animal's gut without being digested.
Comment from Neal: That's pretty disgusting.