What makes owls so mysterious to us? They have had a powerful hold on the human imagination across centuries and cultures, appearing as warnings of doom and as symbols of wisdom. Of course, we know that most are nocturnal, and their nighttime habits may make them seem scary or spooky to us. We think of them flying silently over churchyards, and their eyes seem to glow in the dark. But there's nothing supernatural about the acute hearing and sight of owls. Far from fearing them, we should appreciate owls as competent predators that hunt mice and other rodents, helping to maintain a balance in nature.
NAME THAT OWL
While most of us have no problem identifying an owl—just look for that round face, sharp, hooked bill, and large eyes—it's not as easy to distinguish between different kinds of owls. Even scientists have trouble placing some species in the two family groups: barn owls and typical owls. You have to look carefully at their facial disc (for example, all barn owls have a heart-shaped facial disc, whereas typical owls have a round one), their feet, and whether or not they have ear tufts. Look for owls near your home, and see if you can identify local species.
OWLS, OWLS EVERYWHERE
BUILT FOR NIGHT LIFE
Everything about an owl's body makes it the ideal bird for night living. An owl has the best night vision of any animal, and its hearing is nearly as acute.
HEARING— Did you know that an owl can hear a mouse stepping on a twig from 75 feet (23 meters) away? Every owl has two huge holes in its skull for ears, along with a facial disc that channels sound into the ear openings. Owl ears don't look like our ears, but they are incredibly good at picking up sounds.
VISION— Animals that are active at night usually have large eyes that let them make use of any available light. With owls, the eyes are so big in comparison to the head that there is little room for eye muscles, meaning owls can't move their eyes. Instead, owls must move their entire head to follow the movement of prey. However, having fixed eyes gives owls better focus, with both eyes looking in the same direction. And even though it seems that owls can twist their head completely around, most owls turn their head no more than 270 degrees in either direction.
FEATHERS— Another important adaptation for owls is silent flight. Where other birds have stiff feathers that make a whooshing sound when they fly, owl feathers have soft edges that allow the birds to fly silently. This is important for owls, as they can swoop down on prey without being heard. The only exceptions are the fishing owls, because hunting over water does not require them to fly silently.
HUNTING STRATEGIES
In the darkness, owls don't soar like eagles or hawks but rather fly low to the ground as they look for prey, from insects and small rodents to smaller birds and fish. Larger owls have been known to carry off young deer, weasels, and foxes. Owls compete with each other for territory and food, but owls of different species can coexist by hunting at different times of the day or night. The great gray owl, the ural owl, and the tawny owl all live in the same range, but the great gray owl is a daytime hunter; it prefers voles as prey. The tawny owl also hunts voles, but only at night, and the ural owl hunts larger prey, such as squirrels.
Owls don't have teeth, so they can't chew their food; they must rip their food apart and swallow the chunks or swallow their prey whole. They cough up or "cast" packets of animal bones and hair they are unable to digest. Dissecting these pellets (as many a biology student has done) reveals the owl's diet. At the San Diego Zoo and San Diego Zoo Safari Park, the owls are offered pre-killed rodents.
*Culled from animals.sandiegozoo.org
No comments:
Post a Comment