Human culture is replete with story and myth extolling the intelligence of the crow, a noisy medium-sized black bird with a stout bill and brown eyes. In the film of Frank Baum’s “Wizard of Oz,” the crow recognizes the scarecrow as a harmless decoy and lands on the frustrated, hapless (but lovable) heap of straw.
In the film of J.M. Barrie’s “Peter Pan,” Peter sings “I Gotta Crow,” because he thinks he is one pretty smart fellow.
Aesop’s thirsty crow in “The Crow and the Pitcher” filled a water jug with pebbles until the water rose within reach. In mythology from ancient times to the present, crows have been considered messengers and keepers of the sacred law.
Crows are members of the corvid family, which includes ravens, blue jays and magpies. Crows are absent from South America and the polar ice caps. There are numerous species worldwide; the North American species is Corvus brachyrhynchos. Other species range in Mexico, which is part of North America.
The American crow breeds in all of the southern Canadian provinces and is a year-round resident of most of the United States, including Evanston. Crows are monogamous. They reach breeding age at three years for females and five for males. The average age for a wild crow is about seven years.
Crows have four basic characteristics going for them. They are omnivorous. They are social. They are adaptable. Their complex brains lead to sophisticated behavior. This suite of qualities creates the American crow’s personality that humans either revere or revile.
As omnivores, crows eat anything, including carrion, berries, seeds, insects and small live animals, including eggs and young in nests. Their large bills cannot pierce the skin of some quarry, so they must wait until an animal decomposes or another predator opens their prey.
As social animals, they live in family groups during nesting season. In fall and winter crows roost in ever-expanding groups as migrants join residents. Crows fly to roosts at sundown. Roosts may number in the tens of thousands.
When roosts are in the middle of a city and create an unhealthy nuisance, it is a challenge to disperse them. Crows are short-distance migrants. Unlike most birds, which migrate at night, they migrate during the day, often individually, but they stop to feed communally.
Crows gang up, or “mob” birds of prey, whom they consider dangerous. People have made friends with crows by feeding them, and it is not unusual for crows to repay the food with gifts. All of these social behaviors are survival mechanisms for individuals and populations.
Being adaptable, with few habitat requirements, they can take advantage of human alterations to the landscape. After European settlers arrived, crow numbers actually increased with the proliferation of large agricultural fields, suburbs, cities, cemeteries, parks, dumps and roadkills. Crows will occupy any fairly open area where they can find shelter, food on the ground, and trees or shrubs for nesting. They are partial to areas with water.
Humans have always been fascinated by crows’ intelligence. They have a highly developed brain function with regions, processes and chemical properties that resemble those of primates, although the arrangement is different.
Quoting Marzluff and Angell’s book “Gifts of the Crow,” “The large corvid forebrain devotes more neurons and synapses to organizing and shaping a behavioral response to sensory information than that of any other animal, except parrots, monkeys, and some cetaceans [marine mammals]….These large brain regions have distinct subregions, because sending electrical and chemical messages across long reaches is less precise and takes longer than short-distance communication….which is why corvids have so many nuanced behaviors.”
Neuroscientists are studying the crow brain to learn which subregions light up during different activities and emotions. It is hard not to anthropomorphize when talking about crows, because so many of their behaviors seem to mimic what humans do and feel, such as play, grief, pleasure, risk-taking and awareness of danger.
Crows remember. They cache food and find it easily, even if later buried by snow. They apparently never forget a face. University of Washington, Seattle, researchers banded a wild crow called Bela, infuriating him. During the following five years, when the researchers occasionally visited campus, Bela and her retinue recognized and attacked them by cawing, screaming and swooping.
Crows can size up a situation and “think” it through, modifying their behavior. Crows patrol Washington State ferry landings, placing nuts in the path of offloading cars. The cars drive over the nuts, crack them, and the crows feast.
During late spring and summer, crows stay together in small family groups. In March, the crow couple returns to the nest tree of previous years. Both sexes start work on a new nest, which may take from one to two weeks to build. Their substantial nests, about two feet in diameter, are constructed from branches and twigs and finely lined with soft materials.
Crows will nest in shrubbery but prefer placing nests 15-60 feet above ground in the crotch of limbs or against trunks of tall trees.
During nesting season, crows are secretive and quiet. After 18 days of incubation by the female, four or five chicks hatch. After a month, when chicks are preparing to leave the nest, the typical noise recommences.
Crows have only one brood per summer. The adults and perhaps some of last year’s young feed the fledglings for about two weeks. Scientists are perplexed about the role of these extra birds and, in fact, they know surprisingly little about the species in general.
Corvid populations in Illinois, Indiana and Ohio were decimated by West Nile Virus in 2003. But crows are making a comeback.
It is a pleasure to watch these canny birds with personality plus when they visit a birdbath. There is a reason to be friendly: They will remember.