Asian House Martin

The adult Asian house martin of the nominate subspecies is 12 centimetres long, dark steel-blue above with a contrasting white rump, grey-washed white underparts and a slightly forked tail. The tail and upperwings are brownish-black and the underwings grey-brown. The legs and feet are brownish-pink and covered with white feathers, the eyes brown and the bill black. The sexes differ little, though the male is somewhat whiter below than the female, especially in fresh plumage. (Wikipedia, general species account)

A migratory swallow, its three subspecies breed in the Himalayas and in central and eastern Asia and spend the winter lower in the mountains or in Southeast Asia. It is locally abundant and expanding northward in Siberia, so there are no conservation concerns. It breeds in colonies, building mud nests under an overhang on a vertical cliff or the wall of a building. Both sexes build the nest, incubate the three or four white eggs and feed the chicks. (Wikipedia, general species account)