Himalayan Swiftlet

This 13–14 cm long swiftlet has swept-back wings that resemble a crescent or a boomerang. The body is slender, and the tail is forked. It is, in many respects, a typical swift, having narrow wings for fast flight, and a wide gape and small beak surrounded by bristles for catching insects in flight. Its legs are very short, preventing the bird from perching, but allowing it to cling to vertical surfaces. It is mainly grey-brown above and paler brown below. It has a pale grey rump and a pale patch above and behind the bill. The sexes are similar, but the juvenile has a less distinct rump. There are five subspecies, differing mainly in the rump tone.

A. b. brevirostris breeds in the Himalayas east to Bangladesh, Myanmar and Thailand. This, the nominate race, is an altitudinal migrant, breeding up to above 4,500 m, but wintering between 900 and 2750 m altitude. A. b. innominata breeds in central China, and winters in southwestern Thailand and the Malay Peninsula. The rump is slightly darker grey than nominate brevirostris A. b. inopina breeds in southwestern China. This is the darkest-rumped race. A. b. rogersi the Indochinese swiftlet, breeds in eastern Myanmar, western Thailand and Laos. This is a small, pale-rumped race. A. b. vulcanorum the volcano swiftlet, breeds in Java, Indonesia on volcanic peaks. …

This swiftlet is a highland species, with a preference for feeding open areas in forests, such as river valleys. A. b. brevirostris breeds up 4,500 m in Nepal and 2200m in central Bhutan, and the forms A. b. rogersi and A. b. inniminata occur up to 2200 m in Thailand. The tiny cup nest is constructed by the male swift from thick saliva and some moss, and is attached to a vertical rock wall in a cave. Nests of this colonial swift may be touching. The clutch is two white eggs. This swiftlet is monogamous and both partners take part in caring for the nestlings. The Himalayan swiftlet, like all swifts, is an aerial insectivore, leaving the cave during the day to forage, and returning to its roost at night. In the evening or bad weather, flocks may descend from the hills to feed over cultivated land. This gregarious species forms flocks typically of about 50 birds, but up to 300 have been recorded. Its flight is mainly gliding due to very long primary feathers and small breast muscles.