Owls are not the only birds that throw up pellets, but because the digestive juices of an owl's stomach aren't as acidic, owl pellets are unique in containing the bones of their previous meal along with fur, feathers, or insect parts. Because bones are much easier to identify than fur or feathers, owl pellets are a great way to learn about predator/prey relationships because with a little skill, you can identify the animals in their pellets.