Knowing Nature – The American Black Crow

(Photo from britannica.com)

The American Crow (Corvus brachyrhynchos)

Characteristics:
Adult American crows are completely black birds weighing on average one pound. The feathers have a glossy and slightly iridescent look. Crows have strong legs and toes. The bill is black with a slight hook on the end. Stiff bristles cover their nostrils. About 20% of male birds are slightly larger than the females.

Young crows are about the same size as adults, but have blue eyes and pink inside the mouth. Both the eyes and mouth darken as the bird becomes an adult. In young birds, the ends of tail feathers are symmetrical and are more pointed than the wide, flat-ended feathers of adults. The wing and tail feathers of the young can become quite brown and ragged through the first winter and spring and only become darker and glossier; like adult feathers after the first molt.

Range:
American crows are native  over North America. They can be found in lower Canada and through the continental United States.

Habitat:
American crows prefer open areas with nearby trees. Agricultural and grassland areas are ideal habitat for crows to forage for their food. American crows will also use nearby woodlots and forest edges for breeding and roosting. American crows thrive in suburban neighborhoods and urban parks, as well as in coastal habitats.

Diet:
American crows are omnivores and will eat almost anything. During the breeding season, crows consume insects and their larvae, worms, fruits, grains, and nuts. They actively hunt and prey on small animals such as frogs, mice, and young rabbits, though they more likely to scavenge carrion such as road kill. They also are significant nest predators, preying on the eggs and nestlings of smaller songbirds. In the fall and winter they eat more nuts, such as walnuts and acorns. On rare occasions, American crows will eat from bird feeders put out by humans. Crows often take advantage of human garbage.
American crows store food items such as meat and nuts in short-term caches. Hiding places  are scattered around, rather than in one place. They may be in tree crevices or on the ground, where they are often covered with leaves or other material.
Crows forage primarily by walking on the ground and picking up the item, or by walking along tree branches. Foraging is usually done by a few individuals in a small area, but can also occur in groups over a larger area.
Crows will hold a nut under one foot and strike it with the bill to open it. To open a particularly heavy-shelled food items such as a walnuts or clams, a crow will fly high and drop it on a hard surface.

Communication:
American Crows are highly vocal. Unlike most other songbirds, males and females have the same songs. They have a complex system of loud, harsh caws often uttered in repetitive rhythmic series. Shorter and sharper caws called “kos” are probably alarm or alert calls. Slightly longer caws are probably used in territorial defense, and patterns of repetition may be matched in what may be considered “counter-singing,” or exchanges between territorial neighbors. “Double caws,” short caws repeated in stereotyped doublets, may serve as a call-to-arms vocalization, alerting family members to territorial intruders. Sometimes pairs or family members coordinate their cawing in a duet or chorus. Harsher cawing is used while mobbing potential predators.
People are less familiar with the large variety of softer calls crows can make. Melodic, highly variable coos accompanied by bowing postures are used among family members, possibly as greetings or other bonding signals. Coos of cage-mates become similar over time; this vocalization may therefore be the basis of the mimicry ability shown by pet crows. Crows also give several kinds of rattles.
Young crows make gargling sounds that eventually turn into adult vocalizations. Yearling crows also “ramble” or run through long sequences of different patterns and rhythms of cawing.

Life Cycle:
Breeding in American crows may begin as early as February and last through June. Nests are usually built by both males and females high in a sturdy conifer or hardwood tree. Females lay 4 to 5 light green colored eggs with brown markings. The female incubates her eggs, and they hatch after 18 days. While sitting on the nest, the female will beg for food like a baby bird, and her mate will bring it to her.

by Bill Church

Bill Church is a certified WV Master Naturalist and herbalist. He has published a book, “Medicinal Plants, Trees, & Shrubs of Appalachia.” His articles are provided, courtesy of Gilmer County Master Naturalist Association.