Rook

The rook (Corvus frugilegus) is a passerine bird belonging to the family Corvidae. It is a sizable bird, with adults typically weighing between 280 to 340 grams, measuring 44 to 46 centimeters in length, and boasting a wingspan of 81 to 99 centimeters. The plumage is predominantly black, exhibiting a blue or bluish-purple sheen when illuminated by sunlight. The feathers are particularly dense and silky around the head, neck, and shoulders. The legs and feet are black, the bill is grey-black, and the iris is dark brown. A notable feature of the adult rook is the whitish, featherless area around the base of the bill and in front of the eye, which gives the impression of a longer bill and a more domed head.

Identification Tips

To distinguish the rook from other corvids, observe the bare patch of skin near the bill, which is absent in juveniles and other crow species. The rook's wings are also proportionally longer and narrower than those of the carrion crow when observed in flight. Juvenile rooks can be identified by their black plumage with a greenish gloss and the absence of the bare facial patch.

Habitat

Rooks prefer open agricultural areas with pasture or arable land, provided there are tall trees suitable for nesting. They typically avoid dense forests, swamps, marshes, heaths, and moorlands. These birds are commonly found in lowland areas, often nesting near farms, villages, and open towns, but not in densely built-up regions.

Distribution

The rook is found across the Palearctic, from Scandinavia and western Europe to eastern Siberia. The western rook subspecies is resident in the British Isles and much of north and central Europe, while the eastern rook subspecies ranges from central Siberia and northern Mongolia eastwards across Asia. Some northern populations may migrate southwards in winter to escape harsh conditions.

Behaviour

Rooks are highly social and gregarious, often seen in flocks. They are monogamous, with pairs forming lifelong bonds and staying together within the flock. These birds are diurnal, foraging on the ground during the day and roosting communally at night. They exhibit complex social behaviors and are known for their intelligence and problem-solving abilities.

Song & Calls

The rook's call is a distinctive caw or kaah, variable in pitch and used in different contexts. It is less raucous than that of the carrion crow and is often heard in flight or while perched, where the bird may fan its tail and bow with each call.

Breeding

Rooks nest colonially in rookeries located at the tops of tall trees. Both sexes contribute to nest-building, which is a cup-shaped structure made of sticks and lined with softer materials. The breeding season begins in spring, with egg-laying occurring by the end of March or early April in Britain, and possibly later in eastern Europe and Russia. The clutch size ranges from three to five eggs, which are incubated primarily by the female.

Similar Species

The carrion crow is the most similar species to the rook but can be differentiated by the absence of the bare facial patch and its shorter, broader wings.

Diet and Feeding

Rooks primarily feed on vegetable matter, including cereals, potatoes, roots, fruit, acorns, berries, and seeds, as well as animal matter such as earthworms, insect larvae, beetles, spiders, millipedes, slugs, snails, small mammals, and birds. They forage by probing the ground with their strong bills.

Conservation Status

The rook is classified as Least Concern by the IUCN. While there may be slight declines in population numbers, these are not rapid enough to cause significant concern. The species faces threats from changes in agricultural practices, pesticides, and persecution through shooting.