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The Carletonian

The Carletonian

The Carletonian

Come investigate owl pellets in the Cowling Arboretum!

<oming Monday 5:30-6:30PM, February 20, 2018 there will be an owl Arb walk leaving from the Rec Center. We will learn to listen for owl calls, where to find them, their habits, life cycles, and more. One especially exciting experience will be investigating owl pellets first hand! There will multiple pellets to inspect and even one you can pick through to learn what they eat.

Owl digestion is unique for a variety of reasons. We can start with the first step: food intake. Owls cannot chew their food, so their prey must be swallowed whole or torn into smaller pieces. Also, most birds have a muscular pouch in their throat called a crop that holds food. Since owls do not have a crop all prey passes straight to their stomachs.

Similar to our two-part stomach, they produce enzymes, acid, and mucus in the glandular half that begin the process of digestion. What is unique is that their muscular stomach, the second half, called a gizzard is used as a digestive juice sluice. The gizzard holds back indigestible items like bone, fur, and teeth while soluble meaty parts are churned up and passed to the rest of the digestive system. This lack of solid fiber is why bird excretion is largely liquid.

After a few hours of churning and compression in the gizzard, the indigestible skulls, claws, fur, teeth, and feathers are compacted into a gizzard shaped pellet. The pellet is squeezed back to the glandular stomach. During the pellet’s time in the stomach further food intake is not possible. Once an owl swallows prey they only have a few hours to catch more food so that the indigestible parts can be consolidated in the gizzard as one pellet. After the pellet is passed back to the granular stomach, pellets remain in the owl for about 10 hours and then are regurgitated. Regurgitation indicates readiness to hunt again.

Now that you know how pellets are made, come see the pellets on Monday and learn even more about owls!

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