2010-05-20 / Outdoors

Gross, but fascinating: Pellets revel owl’s diet details

BY LEE BELANGER
Special to Florida Weekly

An open owl pellet. pe op COURTESY PHOTO An open owl pellet. pe op COURTESY PHOTO Owl pellets: what are they? Amazingly, they are balls of compressed bones and fur that owls “cough up” after swallowing an animal whole. Owls use their hooked beak to tear meat from large animals such as rabbits, discarding bones and fur. But a hungry owl will swallow small animals in one gulp.

Unlike other birds, owls have no crop, a place in the throat to store food. Without a crop, an owl’s food goes straight to the first of its two stomachs. The first stomach produces acids that begin digestion. The second (a gizzard) lacks acids. It filters and holds back insoluble items: bones, fur, teeth and feathers. The gizzard presses these inedible remains into a pellet that then moves back to the first stomach. Hours later, this mass is eliminated through the owl's mouth. The owl cannot eat again until the stored pellet is expelled because its digestive tract is blocked. Enzymes from the liver and pancreas further digest the edible food. The owl excretes unused parts of this food as familiar white or gray bird droppings.

Owls are creatures of habit. They usually have a fav favorite roost near their nest to perch and expel pellets. With eyes closed, an owl stretches its neck; open its beak, and the pellet pops out.

You may enjoy searching for owl roosts and pellets. Most owls hunt at night but barred owls hunt in the day as well. Their daytime hoots can help you locate their pellets. Look in areas where you’ve heard owls call. Roosts are often in solitary trees or in an isolated group of trees. Notice white splashes of droppings on the ground under horizontal branches. You may also see fur or feathers from larger animals an owl has torn apart. Owl pellets contain bacteria so if you want to dissect one, it is safer to buy sterilized ones from a supplier. Pellets have little odor and no flesh. Those from suppliers have no odor and are completely dry. Suppliers are listed on the Internet under “Owl Pellets.”

To start your dissection, all you’ll need is a pellet, some open newspaper covered with a sheet of white paper, and toothpicks or tweezers. Place the pellet on the paper and slowly and carefully pull the pellet apart. A magnifying glass helps in identifying tiny bones. Most suppliers will send pictures of animal bones found in their pellets. Use this chart to match bones to the animal.

Each pellet may contain only one animal or parts of several animals if the owl ate more than one animal at one time. Depending on the owl pellet, you’ll find mice, voles, birds, insect skeletons or shrews. A great horned owl pellet usually contains larger animals: squirrels, muskrats or skunks.

Most children love dissecting pellets. If there is a bone chart available, children enjoy gluing the bones to paper and labeling them with each bone name. This is a great grandparent/grandchild project.

Owls are an important part of nature. Florida sugar cane farmers put up barn owl nest boxes to control rodents. Just one family of barn owls can eat 3,000 mice in one year. Owls also eat insect pests and may eliminate any need for pesticides. Beyond their economic importance, their sultry hoots bring pleasure to most who hear them. 

— Lee Belanger is a volunteer at

 

the Rookery Bay National Estuarine

 

 

 

 

 

 

 

 

Research Reserve.

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