Carrion Crow

Appearance

The plumage of Carrion Crow is black with a green or purple sheen, much greener than the gloss of the Rook. The bill, legs and feet are also black. It can be distinguished from the Common Raven by its size and from the Hooded Crow by its black plumage, but there is frequent confusion between it and the Rook. The beak of the Crow is stouter and in consequence looks shorter, and whereas in the adult Rook the nostrils are bare, those of the Crow are covered at all ages with bristle-like feathers.

Behavior

The Rook is generally gregarious and the Crow solitary, but Rooks occasionally nest in isolated trees, and Crows may feed with Rooks; moreover, Crows are often sociable in winter roosts. The most distinctive feature is the voice. The rook has a high-pitched "kaaa", but the Crow's guttural, slightly vibrant, deeper croaked "kraa" is distinct from any note of the rook.

The Carrion Crow is noisy, perching on the top of a tree and calling three or four times in quick succession, with a slight pause between each series of croaks. The wing-beats are slower, more deliberate than those of the Rook.

Like all Corvids, Carrion Crows are highly intelligent, and are among the most intelligent of all animals.

Habitat

This species breeds in western and central Europe, with an allied form or race "C. c. orientalis" occurring in eastern Asia. The separation of these two populations is now believed to have taken place during the last ice age, with the closely allied Hooded Crow filling the gap between. Fertile hybrids occur along the boundary between these two forms indicating their close genetic relationship. This is an example of the parapatric speciation model described by Ernst Mayr. The range of this hybrid of these two species appears to be moving to the northwest.

Reproduction

The bulky stick nest is usually placed in a tall tree, but cliff ledges, old buildings and pylons may be used as well. Nests are also occasionally placed on or near the ground. The nest resembles that of the Common Raven, but is less bulky. The four to six brown-speckled blue or greenish eggs are incubated for 17–19 days by the female alone, who is fed by the male. The young fledge after 32–36 days.

It is not uncommon for an offspring from the previous years to stay around and help rear the new hatchlings. Instead of seeking out a mate, it looks for food and assists the parents in feeding the young.

Food

Though an eater of carrion of all kinds, the Carrion Crow will eat insects, worms, grain, small mammals, and scraps and will also steal eggs. Crows are scavengers by nature, which is why they tend to frequent sites inhabited by humans in order to feed on their household waste. Crows will also harass birds of prey or even foxes for their kills. Crows actively hunt and occasionally co-operate with other crows to make kills.