EDITED TO ADD: Owl pellets leave the owl via the same orifice through which the material entered. Owls tend to swallow their prey whole and twelve hours later the indigestible matter is regurgitated in a neat bundle of fur and bones. Owl poop is less interesting to poke through; it looks like Wite-Out®.
FURTHERMORE: It's fun because you find stuff like a jaw, scapula (these are probably from a mole), vertebrae, or a delightful rodent skull.
