On the wild side—November, 2013
by Tina Mitchell
The American Crow is a member of the fascinating Corvid family, which also includes ravens, magpies, jays, and nutcrackers. As members of the Corvus genus, crows and ravens make up nearly half of the Corvid family worldwide. The scientific name of the American Crow, Corvus brachyrhynchos, reflects its close relationship with ravens. It derives from Latin and Greek for “short-beaked raven.” (Indeed, an American Crow’s beak is considerably shorter and less massive than a Common Raven’s beak.) Its common name is an onomatopoetic representation of its “caw” call.
A large, sturdy, all-black bird with a straight heavy bill, an American Crow can sometimes be difficult to differentiate from its larger cousin, the Common Raven. However, ravens are roughly 1/3 larger, a much thicker and larger bill, produce an unmistakably deeper, raspy call. The only crow species commonly seen in Colorado is the American Crow. Here, crows can be found as high up as 10,000 feet. Crows seem to prefer to nest in conifers. A typical clutch contains 3 – 6 eggs, which hatch in about 18 days. Nestlings leave the nest after about 30 days. However, they usually fledge well before they can live independently. As a result, the adults provide weeks or even months of support and learning opportunities. (Crows do not breed until they are at least 2 years old—and often wait until they are 4 or older. During this interim, they may help raise and tend younger siblings.) Crows in our area don’t migrate. Instead, in the fall and winter, you’ll often see large flocks of crows, probably made up of a number of family groups—all helping to teach this year’s youngsters the ropes. Juvenile crows are about the same size as adults but they have blue or gray-blue eyes and red inside their mouths.
In their diet, adult crows are opportunistic omnivores. They eat a wide variety of insects; amphibians, reptiles, and small fish; small mammals; bird eggs, nestlings and fledglings; nuts, etc. They will even snatch food from an outdoor dog dish or rip open your garbage bags to look for something interesting there.
In the early 2000s, American Crows were one of the major victims of West Nile virus. Early in the epidemic in North America, they experienced nearly 100% mortality from the initial strain of the virus, dying within one week of infection. No other North American species died at the same rate from the disease. Today, though, the disease-resistant survivors are breeding and the American Crow population is on the upswing again.
When you see a large gathering of crows, you might call it a “flock.” But specialized terms have been applied to groups of some species. For example, you may be familiar with a gaggle of geese or a covey of quail. Did you know that a group of crows is called a “murder of crows?” Dating back to as early as 1450, this term may have arisen from their proclivity for eating carrion (dead animals). Perhaps simple opportunistic feeding led to incorrect causal conclusions—folks may have thought that the crows actually killed the animal. We’ll never know, so feel free to concoct your own explanation.
Members of the Corvid family are thought to be extremely intelligent. Crows have been documented using tools in clever ways. For example, a researcher was climbing to a crow nest to band nestlings when one of the parents broke off a pine cone and dropped it on the climber’s head—hitting him 3 different times! Others have reported a crow dropping nuts onto a road, waiting for traffic to clear, and then gathering the smashed bounty. As a testament to their innate intelligence, Henry Ward Beecher once said, “If people wore feathers and wings, very few would be clever enough to be crows.” No “bird brains,” these birds!
You can learn more about this fascinating species here.