American Crow

Appearance

The American Crow is a distinctive bird with iridescent black feathers all over. Its legs, feet and bill are also black. They measure 40–53 cm in length, of which the tail makes up about 40%. The wing chord is 24.5 to 33 cm, with the wingspan ranging from 85 to 100 cm. The bill length can be from 3 to 5.5 cm, varying strongly according to location. The tarsus is 5.5 to 6.5 cm and the tail is 13.5 to 19 cm. The body mass can vary from 316 to 620 g. Males tend to be larger than females.

The most usual call is a loud, short, and rapid "caaw-caaw-caaw". Usually, the birds thrust their heads up and down as they utter this call. American Crows can also produce a wide variety of sounds and sometimes mimic noises made by other animals, including other birds.

Visual differentiation from the Fish Crow is extremely difficult and often inaccurate. Nonetheless, differences apart from size do exist. Fish Crows tend to have more slender bills and feet. There may also be a small sharp hook at the end of the upper bill. Fish Crows also appear as if they have shorter legs when walking. More dramatically, when calling, Fish Crows tend to hunch and fluff their throat feathers.

If seen flying at a distance from where size estimates are unreliable, the distinctly larger Common Ravens can be distinguished by their almost lozenge-shaped tail, their larger-looking heads and of course their strongly solitary habits. They also fluff their throat feathers when calling like Fish Crows, only more so.

Most wild American Crows live for about 7–8 years. Captive birds are known to have lived up to 30 years.

Naming

Four subspecies are recognized. They differ in bill proportion and form a rough NE-SW clinal in size across North America. Birds are smallest in the far west and on the south coast.
⤷ "Corvus brachyrhynchos brachyrhynchos" – Eastern Crow: northeastern United States, eastern Canada and surroundings. Largest subspecies.
⤷ "Corvus brachyrhynchos hesperis" – Western Crow: Western North America except arctic north, Pacific Northwest and extreme south. Smaller overall with a proportionally more slender bill and low-pitched voice.
⤷ "Corvus brachyrhynchos pascuus" – Florida Crow: Florida. Mid-sized, short-winged but decidedly long bill and legs.
⤷ "Corvus brachyrhynchos paulus" – Southern Crow: southern United States. Smaller overall, bill also small.

Distribution

The range of the American Crow extends from the Pacific Ocean to the Atlantic Ocean in Canada, on the French islands of Saint-Pierre and Miquelon, south through the United States, and into northern Mexico.

Status

Crows have been killed in large numbers by humans, both for recreation and as part of organized campaigns of extermination.

American Crows are protected internationally by the Migratory Bird Treaty Act of 1918. Despite attempts by humans in some areas to drive away or eliminate these birds, they remain widespread and very common. The number of individual American Crows is estimated by Birdlife International to be around 31,000,000. The large population, as well as its vast range, are the reasons why the American Crow is considered to be of least concern, meaning that the species is not threatened.

Habitat

Virtually all types of country from wilderness, farmland, parks, open woodland to towns and major cities are inhabited; it is absent only from Pacific temperate rain forests and tundra habitat where it is replaced by the raven. This crow is a permanent resident in most of the USA, but most Canadian birds migrate some distances southward in winter. Outside of the nesting season these birds often gather in large communal roosts at night.

The American Crow was recorded in Bermuda from 1876 onwards.

Reproduction

American Crows are monogamous cooperative breeding birds. Mated pairs form large families of up to 15 individuals from several breeding seasons that remain together for many years. Offspring from a previous nesting season will usually remain with the family to assist in rearing new nestlings. American Crows do not reach breeding age for at least two years. Most do not leave the nest to breed for four to five years.

The nesting season starts early, with some birds incubating eggs by early April. American Crows build bulky stick nests, nearly always in trees but sometimes also in large bushes and, very rarely, on the ground. They will nest in a wide variety of trees, including large conifers, although oaks are most often used. Three to six eggs are laid and incubated for 18 days. The young are usually fledged by about 35 days after hatching. Predation primarily occurs at the nest site and eggs and nestlings are frequently eaten by snakes, raccoons, ravens and domestic cats. Adults are less frequently predated but face potential attack from Great Horned Owls, Red-tailed Hawks, Peregrine Falcons and eagles. They may be attacked by predators such as coyotes or bobcats at carrion when incautious although this is even rarer.

Food

The American Crow is omnivorous. It will feed on invertebrates of all types, carrion, scraps of human food, seeds, eggs and nestlings, stranded fish on the shore and various grains. American Crows are active hunters and will prey on mice, frogs, and other small animals. In winter and autumn, the diet of American Crows is more dependent on nuts and acorns. Occasionally, they will visit bird feeders. The American Crow is one of only a few species of bird that has been observed modifying and using tools to obtain food.

Like most crows, they will scavenge at landfills, scattering garbage in the process. Where available, corn, wheat and other crops are a favorite food. These habits have historically caused the American Crow to be considered a nuisance. However, it is suspected that the harm to crops is offset by the service the American Crow provides by eating insect pests.