Description. The whole plumage black; the head, neck and lower plumage richly glossed with purplish blue, the upper plumage with violet-purple; the base of the bill and face without any feathers and showing up white.
The Eastern race differs from the typical bird in being smaller and especially in having a smaller, more slender bill.
Colours of soft parts. Bill and feet black; iris deep brown; facial skin white.
Measurements. Total length about 480 mm. or less; wing about 300 mm.; tail about 160 mm.; culmen 52 to 60 mm.
The Nestling is without any gloss at first, but quickly assumes it. Until about 10 to 12 months old the face is fully feathered; the nasal bristles are then cast, and by the time the bird is a year old the face is entirely denuded of feathers. Whitehead says that the Eastern form does not shed its facial feathers until April or until it is practically a year old.
Nidification. The Eastern Rook breeds in Persia, Turkestan and North-West Siberia, and probably Ladakh. A nest taken for me by a native collecter was built on a small tree and contained three eggs, similar to those of the Common Rook and measuring 34.0 × 26.0; 33.6 × 25.9; and 34.1 × 25.0 mm. The female was shot on the nest.
Habits. The Eastern Rook is a very common winter visitor to the North-West Himalayas and occasionally wanders into the plains, having been killed at Abbottabad. Whitehead and Magrath report it as visiting Kohat in enormous numbers. The Rook frequents the better cultivated parts of the country and feeds in ploughed and grass-covered lands on worms, snails, grubs and grasshoppers, etc. In Europe the Western form breeds in large societies but there is little on record about the Eastern form.