The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, October 08, 2006

American Crows Are Too Often Taken for Granted
by Ro Wauer

American Crows are one of our most common native birds, and they are one of our most obvious species. And yet, in spite of that, they are usually ignored and forgotten. The exceptions include farmers that must chase them away from plantings and birders who count them along with all of the other wintertime birds during the annual Christmas Bird Counts. But American crows, known to ornithologists as Corvus brachyrhynchos, are abundant throughout our area of Texas and throughout the eastern half of the state.

Their range does not, however, extend very far south of the San Antonio River or westward into West Texas. They are replaced to the south and in much of the western portion of the state by the Chihuahaun raven, and by the fish crow along the eastern edge of the state, both crow look-alikes. And the common raven, a similar but larger version of the crow, occurs throughout the mountainous portion of West Texas and the western portion of the Hill Country. Plus, a fifth crow-like bird, the Tamaulipas crow, occurs only in a small area near Brownsville. This species is abundant throughout much of Mexico, only reaching the United States in deep southern Texas.

All five of these birds are closely related according to taxonomists, who have lumped them all into the genus Corvus. They do differ somewhat in size, with the common raven being the largest, and the fish and Tamaulipas crows being the smallest. In places where their ranges overlap, they can best be identified by their rather unique voices. But all have the basic "caw" calls, although the common raven has a deeper call, the fish crow's call is higher and more nasal in quality, the Chihuahuan raven's call is a drawn out croak, and the Tamaulipas crow's call is like a low, froglike croak. Only the American crow, our local Corvus, has the typical caw call that is often given in a series.

American crows are a wary and suspicious bird that spends much of its time in fields and pastures, only rarely spending much time in urban areas. However, these adaptable and resourceful birds, that almost always occur in flocks, can appear wherever food is available. They will then post a lookout to warn the group of any danger, while the remainder of the flock feeds on whatever food they have found. Their diet can vary considerably. Harry Oberholser wrote in his book, The Bird Life of Texas, that "the omnivorous Common [crows] eats what the season and locality provide, its diet including insects, crustaceans, snails, reptiles, small mammals, carrion, grain, and edible trash discarded by humans; also eggs and young of wild birds." When feeding on mollusks, they will drop the shells onto rocks from a considerably height to break the shells so they can reach the soft body parts.

The entire crow/raven group of birds is considered one of the smartest of all North American birds. They have not only survived in great numbers over the years, when so many other species have declined from pesticides and habitat loss, but some pet crows have even learned to mimic human vocalizations.

During the breeding season, that in the south can extend from early spring into the fall, and may include two broods, American crow courtship can be rather vigorous. Males pursue females in flight and among the trees or on the ground where they often fluff their body feathers, spread their tail, and bows several times to their lady while uttering rattling call notes. They will then perch together, preen one another and touch bills.

Nests are constructed on trees, usually well hidden among the higher foliage, although there are records of ground nests. Nests are constructed of branches, twigs, and bark, and are lined with shredded bark, leaves, grass, and hair. Four to six bluish-green eggs are then laid, and young leave the nests in 28 to 35 days. These same youngsters will often serve as helpers to their parents, in nest construction and feeding the nestlings of a second brood.

The native American crow is truly a fascinating member of our avian community!


At 3:57 PM, Blogger MsJamie said...

I love crows. I was watching two in a tree and thought they were courting, and heard that strange call. I was looking to confirm that it was courtship. Thanks for the information. I got a few pictures of them with the zoom, but I moved closer to take more pictures and I think when they noticed me watching, the male flew off.

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