Corvus corax

Crystal Carpenter, a naturalist at Antelope Island State Park, took this picture showing a common raven, great horned owl and, lurking behind the owl, the tail of a black-billed magpie. The birds were all perched on the window sill at the visitor center on Antelope Island.

It is not the usual grouping. What is happening? The raven and magpie are mobbing the owl.

The raven and the magpie belong to the corvid family of birds, along with crows and jays.

Corvids are among the smartest of the birds. They know that the owl is a predator and that they have the advantage in daylight. The owl probably wishes they would disappear. If not, it will be forced to move out of their territory.

Ravens are found throughout Utah. They range from Mexico north between the West Coast and the Rocky Mountains into Canada and Alaska. They are highly successful songbirds. They will eat anything they can swallow. They will take carrion, as well as eggs, chicks, grain, mice, frogs, fruit and much more.

The raven is an all-black bird, as large as a hawk at 25 inches in length, with a wing span of 56 inches. It is the largest perching bird in North America. Ravens soar, while crows flap. They are larger than crows and have a heavy mandible and a wedge-shaped tail.

Ravens and crows are found in Utah. Crows were once seen only migrating through Utah, but about a dozen years ago they learned how to be dumpster divers. Northern Utah now has a strong number of them throughout the year.

The best way to sort out which you are seeing is to look at the size first. Ravens are about a third larger than crows. A raven's tail is edge-shaped like a fan when flying. The crow's tail is squared on the end. Crows tend to be more of a flocking bird, while ravens are usually seen solo or in pairs.

If you hear them vocalize, the crow has the classical "caw-caw." The raven's call is more of a harsh, echoing croaking.

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* BILL FENIMORE is owner of the Layton Wild Bird Center. Call 801-525-8400 or visit www.wildbird.com/layton for information regarding free bird/nature walks.