Our Window on Nature

. . . exploring the world around us

Rattles From The Sky

Filed under: Birds — Lowell Christie -- February 27, 2016 @ 7:56 pm

Raven_croakVoices clatter overhead like rattling bones in an old calypso song. We’re lucky enough to share the neighborhood with ravens, and they attract our attention every time they pass by. This pair seems determined to prove the suitability of their name, Corvus corax (from the German word for croaker.)

The most common call we hear is a loud, deep-voiced croake-croake. The dry bones rattle, cur-ruk, that we hear less often is given mostly in flight. Naturalists have long known that ravens have a language of their own, but they’ve learned only recently to decipher its meaning. We don’t claim to speak raven, but when our duo flies over they do appear to be deeply engrossed in conversation.

It could be interesting listening, since members of the crow family, which includes ravens as well as jays, possess the highest intelligence known among birds. Captive individuals have learned to count up to four, and they’ve proved to have considerable expertise at solving puzzles. Of greater interest to us are their survival strategies in the wild.

Ravens are basically scavengers, competing with gulls and vultures in eating dead critters. They are usually quite shy of human beings, but in sparsely inhabited areas you may see them feeding on road kills.

Coastal ravens possess feeding habits much like gulls, eating fish, frogs, and tadpoles. They also wrest crabs and shellfish from seaweed or tidepools and drop them from aloft to break their shells. And like gulls, ravens willingly snatch the eggs and young of other birds.  Although they do it less commonly than crows, ravens sometimes follow behind while farmers plow their fields, doing him the favor of gathering up insects exposed by the plow.

A few years ago, Bernd Heinrich wrote an article in Audubon Magazine about the results of his research into raven’s cooperative behavior in finding food. Cooperation is common in the animal world, he wrote, and it is often the key to survival in hostile environments. He devoted many icy hours in central Maine observing ravens finding and feeding on carrion. Ravens lack bills strong enough to tear open the flesh of large animals, so they are dependant upon other scavengers like coyote. But they don’t appear to attract their benefactors, rather to accept their unknowing assistance. They do, Heinrich concluded, communicate with other ravens about the presence of food, giving a particular yelling call he heard on no other occasion.

To bird lovers, when you combine the most intelligent of birds with limited food resources, anything is possible. After all, other members of the crow family, Gray-breasted jays, cooperate in caring for young, and groups of Acorn woodpeckers store acorns in a common granary. Why should ravens be different. Of course, the other species cooperate only among family members.

When seen through binoculars, ravens are elegant birds. Even so, we have difficulty thinking of them as songbirds. They are, in fact, the largest species in that category. Luckily, you don’t have to sing well to be part of the group. Their croaks are interesting, but no one would call them musical.

What they lack in voice, ravens make up for in size. From bill to tail, the bird is about two feet long, with a wingspan twice that length. In spite of the size difference, a raven can be mistaken for a crow when perched. If you get a good look at the head, however, you’ll see full, shaggy throat feathers and a heavy, arched bill (an avian Roman nose).

When flying, their wedge-shaped or rounded tails make ravens easy to separate from their smaller cousins. (Crows generally have straight tails.)

Unlike crows, ravens are magnificent in the air. They alternate flapping and soaring as hawks do, and they can hover like a kestrel and ride thermals as well as larger hawks and vultures.

Ravens pair for life, but each spring the male courts his mate all over again. He may fly with his wing tips touching hers, dive like a peregrine falcon, or tumble over and over in the air. What female could resist such devotion.

Along the Atlantic and Pacific coastline pairs usually nest on rocky cliffs. In the West, ravens build nests on ledges or in trees in mountain forests, on the Great Plains, and in the deserts. We’re delighted to see and hear them, whether in Big Bend where we first met them, at the Grand Canyon where we watched their courtship, or at home. They speak of the wild.


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