Asian House Martin

The adult Asian house martin of the nominate subspecies is 12 cm (4.7 in) 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 are grey-brown. The legs and feet are brownish-pink and covered with white feathers, the eyes are brown, and the bill is black. There are few differences in appearance between the sexes, although the male is somewhat whiter below than the female, especially in fresh plumage. The juvenile bird is less glossy and has dark brown upperparts, sometimes with a brownish wash to the rump, and grey-white underparts. D. d. cashmiriensis has brighter blue upperparts and a whiter rump than the slightly larger nominate race. The third, smallest, race is D. d. nigrimentalis. All three subspecies can be distinguished from the similar Nepal house martin by the latter species' black chin, black undertail coverts and much squarer tail. The Asian house martin is more similar to the common house martin, but is darker underneath and has a less deeply forked tail. Confusion is most likely between adult male Asian house martins, which have paler underparts, and the eastern race of common house martin, D. …

The nominate subspecies of the Asian house martin, D. d. dasypus, breeds in the southeast of Russia, the Kuril Islands, Japan and sometimes Korea. It migrates through eastern China to winter in the Malay Peninsula, Borneo, the Philippines, Java and Sumatra; a few birds remain around hot springs in Japan. D. d. cashmeriensis breeds in the Himalayas from Afghanistan east to Sikkim and northwards into Tibet and western and central China. It is found between 1,500–5,000 m (4,900–16,400 ft) altitude, although mainly in the 2,400–4,000 m (7,900–13,100 ft) range. This martin is a short-range migrant, mainly wintering at lower altitudes in the foothills of the Himalayas, but with some birds on the plains of northeastern India and northeastern and southeastern Bangladesh, and smaller numbers further afield in Myanmar and northern Thailand. The third race, D. d. nigrimentalis, breeds in southeastern China and southern Siberia. Its wintering grounds are unknown, but birds in Taiwan just move to lower altitudes in winter. Non-breeding Asian house martins have been recorded as far west as the United Arab Emirates. The range of D. d. cashmeriensis overlaps with that of the Nepal house martin, although they breed at somewhat different altitudes. …

This martin feeds on insects taken in flight. As with its relatives it tends to feed high in the air, taking mostly small flies, aphids and Hymenoptera such as winged ants. A wide range of other insects are caught, including Lepidoptera, beetles and lacewings. The presence in the diet of terrestrial springtails and Lepidoptera larvae indicates that food is sometimes picked from the ground.