In the Connecticut River watershed, if you drive on a roadway you have seen a crow eating carrion. What you are seeing is the modern American crow, scientific name Corvus brachyrhynchos, the “short-billed crow” descended from 20-million-year-old ancestors.
The American crow is large, up to 21 inches long, weighing over a pound. Crows are omnivorous. They eat just about anything including fruits, vegetables, insects, road kill, birdseed, small rodents, fish, and other birds and their eggs. They communicate with their rude loud cawing.
Crows are social and unless in large roost groups called murders, live in family groups of up to 15 birds. Their natural enemies are the great horned owl and some hawks. Crows exhibit a cooperative defense behavior where they will mob a hawk until it leaves the area. When feeding, even having sent scouts in advance to the feeding area, crows place guards to sound warnings of danger. Why a group of crows is called a murder has been a mystery since the 15th century. One dictionary suggests “murder may allude to the crow’s traditional association with violent death or to its harsh and raucous cry.”
The crow’s number one enemy is man because our negative feelings about crows extend from they are simply annoying to highly destructive especially in agricultural areas. A recent new deadly threat to crows is West Nile virus. The virus, native to east Africa, arrived in New York City in 1999, spreading west and south across America. In the northeast, a study found American crow populations decreased 31% since then. Despite the drop in numbers, the crow is still considered a Species of Least Concern.
Crows incubate a clutch of three to six eggs for 18 days. The eggs are of various colors from sky blue to camouflage brown with spots. The mother will brood the young birds for up to two weeks with the male and one or more prior offspring carrying food back to the nest.
Somewhere between 30 and 40 days after hatching, the young want to leave the nest before they are able to fly. If they do not stay safely in the tree but fall to the ground, the crow family will continue to care for the young. If the fall does not kill them, predators do not eat them or helpful humans do not rescue them, they will rejoin their family.
Outside breeding season crows gather in large numbers at a communal roost just before dark. This arrangement does not mean that individual crows are friendly with all other crows and they may fight for reasons such as defending territory or their nest. Crow family fights usually only involve a few pecks but fights between different families can be deadly. Violence toward a single crow could mean that it was injured, sick, or acting oddly because it might attract predators.
Crows are intelligent. They use tools such as shaping a stick and then sticking it into a hole in a fence post in search of food or breaking off pieces of pine cone to drop on tree climbers near their nest. Their intellect is captured in the Aesop fable depicting a thirsty crow faced with a pitcher half full with water, beyond the reach of its beak. After failing to push over the pitcher, it drops in pebbles, one by one, until the water rises to the top of the pitcher, allowing the crow to drink.
Crows remember the faces of threatening humans, scolding and bringing in others so they learn about the threatening person and spread the information about this individual throughout the crow community.
Given that crows have long memories, people who hunt these birds, for example, could experience years of raucous harassment.
In spite of their discordant song, the crow is a truly exceptional member of the bird family here in the Connecticut River watershed
David L. Deen
River Steward for the Connecticut River Watershed Council.