By Jillaine Burton, Open Door Bird Sanctuary

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Barred owl, by Lori Kemmler

Owls are the predator drones of the night. Seldom seen, these mysterious birds are designed to spot and swoop in on their prey silently and effectively. They flew with the dinosaurs—fossils date them back to more than 50 million years ago. And they are everywhere. Owls are found on all seven continents except Antarctica.

There are more than 150 owl species, most of them found in Asia. There are only 19 species in the United States and Canada. Owls vary considerably in size. The tiny elf owl weighs 1.5 ounces and is little more than 6 inches tall. Eurasian eagle owls, on the other hand, have a wingspan of up to six feet and have been known to prey on monkeys, young warthogs, golden eagles, small deer and foxes.

Owls constitute the largest share of residents currently at Open Door Bird Sanctuary. We have three great horned owls (Blackbeard, Grace O’Malley and Bill), a screech owl (Bob), a Eurasian eagle owl (Aisling), a barred owl (Radar) and a saw-whet owl (Koko).

Bob the screech owl (left) and Koko the saw-whet owl (right) live at Open Door Bird Sanctuary. Photos by Mike Kemmler

Designed for the Hunt

What makes owls such effective hunters? It starts with their head. Their flat, disc-shaped faces funnel sound to their ears, magnifying it up to ten times. On many owls, the left ear and right ear are set at different heights, which allows them to better pinpoint their prey. Their eyes are incredibly powerful binoculars that let them detect a vole or mouse up to a half mile away. Up close, their vision is poor and they must rely on small, hair-like feathers on their beaks and feet to feel out their food after it has been caught. Owls cannot move their eyes; they are fixed in a straight-ahead position. To compensate, owls can rotate their neck 270 degrees thanks to having double the number of vertebrae as most birds and a blood-pooling system that powers their brains and eyes when their neck movement cuts off circulation. Even owls’ wings are designed for stealth. Their broad wings and light bodies make them nearly silent fliers. Specialized feathers with fringes of varying softness are designed to muffle sound.

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Owls have broad wings and lights bodies, and special feather that muffle sound, making them nearly silent in flight. Photo by photophilde via Flickr Creative Commons

Owls are carnivorous and will eat rodents, small- or medium-sized mammals, nocturnal insects, fish and other birds, and even other owls. They can get prey that is in the water, on land and in some circumstances even underground. With their powerful talons they are able to pick up food and continue in flight. After digesting their food, owls regurgitate hard pellets of compressed bones, fur, teeth, feathers and other materials they couldn’t digest.

Most owls do not migrate but they can be nomadic in searching for the best food sources. The saw-whet owl is an exception. Not much is known about the migratory patterns of the saw-whet owl because it is nocturnal and reclusive, but its winter nesting area can extend as far north as central Illinois.

Owls almost always live alone. They may form a pair, though, or a small flock in some locations, but that is very unusual.