What Happens to the Indigestible Parts an Owl Swallows?

The owl is a bird of prey that does not chew its food, but swallows most of it whole. The parts of an animal it cannot safely digest passes through the owl's digestive tract, and becomes regurgitated as an "owl pellet." By studying owl pellets, scientists can learn interesting information about the owl's behavioral patterns. There are 216 owls worldwide, which include 18 in the barn owl family and 198 in the typical owl family.

  1. Digestion in Owls

    • Owls do not have digestive glands in their gizzards. In a bird of prey, the gizzard filters the parts of its food that it cannot safely digest. Owls cannot digest feathers, teeth, bones or fur. The owl pellet is formed within a few hours after it eats is prey, but the owl may not regurgitate it for up to 20 hours. The bird's body spasms until the pellet is expelled, clearing the entrance to the digestive system and allowing it to eat again. Young owls do not produce pellets until they mature enough to eat their prey whole.

    Owl Pellet

    • Unlike other large birds, owls have no "crop." A crop is a loose pouch inside the throat that acts as storage for food which they can consume after their prey has been eaten. Because of this, an owl's food is passed directly into their digestive system. The parts of the owl's prey that cannot be safely digested, including their own reproductive and body waste, is expelled as a pasty white substance called urea. The thick substance becomes an owl pellet.

    Pellet Identification

    • Researchers study owl pellets to discover information about the owls habits and behavioral patterns. Through examination, the pellets reveal a story about the relationship between the owl and its prey since most of the bones are not broken during the owl's digestion. If you find an owl pellet, you can do some detective work of your own. The pellet will be hard and compact, so soften it in water and carefully take it apart, looking at the pieces and bones under a microscope. Owl pellets can be found near barns and under trees.

    Diet

    • Barn owls eat small animals, birds, reptiles, amphibians and insects. Typical owls feed on small animals including rodents, birds, amphibians, fish, crayfish, earthworms and insects. Mice are a favorite of owls, and they will sometimes crush the skull before swallowing the mouse whole. They may also pluck the long wings and tail feathers from a bird before consuming it. Some owls will tear pieces from its larger prey so that the pieces can be swallowed easily.