The Strigiformes (owls) have a different feeding style. These nocturnal hunters usually swallow prey whole. Exceptions, like adult rabbits and skunks (a favorite meal of the Great Horned Owl), must be torn into pieces before ingestion, but most other meals are swallowed complete—bones, feet, hair (or feathers) and all—in one gulp. When a Barn Owl swallows a rat, it is like a 120-lb. person swallowing a 20-lb. steak in one bite. And owls may do this several times each night. Owls always swallow the prey head first, placing it in the beak and positioning it with the talons. Quick, upward thrusts of the owl’s head and neck start the meal through the mouth and into the smooth, flexible esophagus. The owl’s esophagus leads to a glandular stomach where the prey comes to rest. The glandular stomach is similar to the crop found in grain-eating birds, but instead of simply holding grain that will later be ground by a gizzard, the owl’s glandular stomach is a digester used for dissolving and separating the |
parts of
the prey. The glandular stomach is only part of the reason owls can eat like they
do—that is, bones and all. The carcass of the meal protects the owl’s throat
from sharp bones on the trip down, but eventually the bones must be brought back out.
Since owls have no teeth, the bones cannot be ground up to pass through the intestine as
in coyotes, bobcats, and other carnivores. Instead, only the fleshy portions of the prey
are broken down and passed through a second stomach, the muscular stomach. The muscular stomach acts as a strainer by catching the bones, claws, scales, hair and/or feathers of the prey. The fleshy, digestible parts continue beyond this lower stomach and through the intestine where water and nutrient absorption takes place. The strained, undigested materials left behind in the glandular stomach must eventually leave the owl the same way they came in, through the mouth. But loose bones might get lodged in the owl’s throat when regurgitated. To prevent this, the stomach presses hair around the bones and forms a slick bolus. Muscles along the esophagus reverse the direction used in swallowing. With a few head lunges and stomach contractions, a soft package filled with bony remains is expelled from the owl’s mouth. This is what we call an owl pellet. |
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