Clever American crow appeals to the bird in each of us
The shade of the gazebo provided a modicum of relief during one of our countless hot and humid summer days. A wood duck hen and her chicks drifted idly on the lake, apparently as sapped of energy as we were.
The stillness was broken by five big, black birds mobbing a red-tailed hawk. The assault continued as the raucous crows pursued the hawk, taking turns diving at the rapidly retreating raptor.
With a wingspan approaching 40 inches, American crows (Corvus brachyrhynos) are the biggest crows in North America. They are also among the noisiest birds on the continent. Their hoarse “caw-caw” is familiar to all. Their ubiquity does not diminish my fascination with these highly social, intelligent birds.
We were at Lake Artemesia in College Park, MD. The paved path that circles the lake is popular with local families looking for a bit of nature inside the beltway.
Crows have adapted to life in the suburbs. In fact, they are thriving in many landscapes altered by humans. These crows are common to abundant across the lower 48 states. Only the desert Southwest, stretching from west Texas through Arizona, is inhospitable to these highly adaptable birds.
American crows are easy to describe: They are big and black. The plumage is uniformly black and so are the bill and the proportionally long legs. Worn, pre-molt feathers may appear brown, but they are soon replaced by shiny new black feathers.
Crows used to be seen only in woodlands and agricultural fields. But as the human footprint has encroached upon these traditional habitats, crows quickly learned to adapt. In a fascinating study, a researcher found that country crows, which are sometimes hunted, were difficult to get near, but suburban and urban crows were readily approachable. The birds had learned that the latter settings were safe from hunting and often rich sources of food.
American crows are omnivores. They eat worms, larvae, snakes, insects and baby mice. They also eat seeds, berries and fruit. Carrion is a routine part of their diet, not to mention discarded French fries, cat food and just about anything else you can think of.
The mobbing behavior we witnessed was probably carried out by an extended family protecting their large, well-hidden nest. Crows build nests just short of a tree’s apex (hence a “crow’s nest” on ships).
Crows mate for life, and their young often stay with their parents for more than a year. They are “cooperative breeders,” meaning they are similar to extended families in traditional human societies. Young do not become sexually mature until age 2, and females often stay with parents for the first three years. Male young may stay four years or even longer.
Although only the mother incubates eggs, feeding the chicks is a family affair with older siblings joining the parents in bringing food to the nest. As a unit, the family protects its territory, as we witnessed when the crows chased away the potential nest predator.
Away from their territory, crows are highly social. Especially during winter, when they can congregate into huge flocks. Throughout the Susquehanna River valley, with its plentiful forests and farms, flocks of more than 10,000 crows are common in winter.
Crows aren’t simply social; they are also smart.
Ornithologists have been studying crows for decades. Some of the 40-plus crow species worldwide can be taught to mimic human speech. Many can also solve problems. In one experiment, a crow was placed in a cage that contained a tiny pail of meat at the bottom of a Plexiglas tube. A length of wire, which the bird had never before seen, was also in the cage. In due course, the crow took up the wire. After efforts to skewer the meat proved unsuccessful, the crow bent the wire to form a hook. Using the hook, the bird snagged the handle of the pail and lifted it out of the tube and promptly enjoyed its food.
Crows can recognize individual human faces and interact with people. They can anticipate future events and take appropriate action. They can transmit social learning to young, a hallmark of cultural transmission. It is little wonder that one researcher calls them “feathered apes,” because of their primate-like cognitive and social characteristics.
Scientists warn about anthropomorphizing, ascribing human characteristics to animals. But crows make me think the concern is misplaced. We should be careful not to claim unto ourselves actions and behaviors that we share with the animal world. More than a century and a half after Darwin, we are still learning that we are simply part of a vast complex of living creatures that differs by degree, not kind.
As I watched the crow family return to its nest territory, I think I saw some fragments of shared DNA code. Perhaps there is some crow in all of us.