The Common Crow (Corvus brachyrhynchos) is a large black bird commonly seen and heard throughout Vermont. The crow is in the Corvidae family, which also includes ravens, jays, and magpies.
These birds have loud and raucous calls that are quite unlike the songs of many other birds. Although the crow may eat agricultural crops, it also consumes enormous amounts of harmful grasshoppers, cutworms, and insects.
The crow is a curious bird, and is known to carry off and hide bright, shiny objects.
Common Crows are opportunistic and are able to occupy a wide variety of habitats. They can live in towns and cities, as well as in forests and farmlands. They require open areas for feeding as well as trees for nesting sites. Crows prefer areas that have both fields and woodlots, to areas with just one or the other.
According to ornithologists, crows and other members of the Corvidae family are some of the most intelligent bird species. There are several characteristics unique to crows that support this fact. Crows often travel and feed in large flocks. During feeding, one or two birds may serve as a lookout while the others feed and, at any sign of danger, the guards warn the rest of the flock. By working in this way, the flock is able to feed more efficiently.
Another indication of their intelligence is the variation in their vocalizations. They can express warnings, threats, and sounds of pleasure.
Crows are also known to interact with other animals such as wolves, coyotes, and mountain lions. A flock of crows may lead one of these predators to a carcass so it can be opened by the predator and thereby allow the crows to also feed on the carrion.
A recent study shows that they even have a unique family structure. Adult crows never chase away their offspring and the young often stay with the adults to help raise and defend the next brood. This is uncommon among other bird species.
In early spring, large flocks of crows break up into small groups of two to five birds, usually made up of parents and last year's offspring. The male courts the female either on the ground or in trees. During this display, the male will fluff its wing and tail feathers, bob his head, and utter a breeding song. The mating pair will then perch together and preen each other as part of the mating process.
During this time, the pair will also establish a territory. The male and female construct the nest together from late-March to mid-April. The crows build large nests about 12 inches in diameter, out of sticks, weed stalks, and vines, then line it with feathers, grass, and small roots.
Nests are placed in the fork of a tree, preferably a coniferous tree, at an average height of 42 feet. The crows may also nest on cliff ledges or occasionally on the ground. Nesting occurs in a variety of habitats including mature forests, woodlots, and coniferous woods.
The female lays three to eight blue-green eggs, with gray or dark brown splotches. Both the male and female incubate the eggs for 18 days. Both the male and the female will also care for the young once they hatch.
At birth, the chicks' eyes are closed but by their fifth day, they can see. The young crows are fully feathered at four weeks and fledge, or learn to fly, by late June. They will stay with their parents all summer and into the following year. Crows raise one brood annually.
Once the young have left the nest, the crows gather together in large groups to roost. These flocks can grow to be as large as 100,000 crows in number. They roost together at night and break into smaller groups for feeding during the day.
The crow is omnivorous, eating both plant and animal matter, and is not selective about what it eats. Its varied diet includes small rodents, eggs and baby birds, amphibians, insects, carrion, seeds, nuts, berries and corn.
An adult crow eats approximately its weight in food every day. The crow, like the owl, regurgitates indigestible material, such as bone and fur, in the form of pellets.
A large portion of its diet consists of insects and carrion, or dead meat. Particularly during the summer, research suggests that insects make up two thirds of the crow's diet. Beetles, termites, ants and several other insect species are commonly eaten by the crow, which helps farmers as a natural method of crop damage control.
The crow also eats large quantities of carrion. It can often be seen along roadsides, dodging cars in order to scavenge animals killed on the road or at picnic sites cleaning up after humans.
Current crow populations within the state of Vermont are stable. However, West Nile Virus may have temporarily impacted the population. There is no active plan designed for this species, but continued monitoring is conducted to ensure that their population remains healthy and abundant in Vermont.
Crows reach their highest numbers where there is a mix of agricultural land and mature woodlands. In Vermont, these areas include the Champlain Valley and Connecticut River Valley. The scattered hill farms within the Green Mountains are also attractive. The lowest population is in the Northeast Kingdom. Crows are extremely resourceful and can adapt to almost any environment, including, hardwood forest, riparian areas, wetlands and coniferous forests.
Crows are considered year-round residents of Vermont, but they may undergo some short migrations to neighboring states to the south. There is also an elevation migration pattern in many of these birds. That is, many crows will leave the Green Mountains during the winter months and reside in the Champlain and Connecticut River Valleys. The higher human population in the valleys probably provides a wider variety of food sources compared to the upper elevations.