Himalayan Swiftlet

The Himalayan swiftlet, Aerodramus brevirostris, is a small, slender bird with a body length of 13-14 cm. It boasts swept-back wings that form a crescent or boomerang shape, and a forked tail. Its plumage is mainly grey-brown on the upper side and paler brown on the underside, with a pale grey rump and a distinct pale patch above and behind the bill. Both sexes appear similar, though juveniles can be identified by a less pronounced rump.

Identification Tips

To identify the Himalayan swiftlet, look for its crescent-shaped wings and swift flight. The pale grey rump and patch near the bill are key features, as is the forked tail. Juveniles may be distinguished by their less distinct rump. There are five subspecies, which vary mainly in the tone of their rump.

Habitat

This highland swiftlet favors open areas in forests, such as river valleys, for feeding. It is adapted to cling to vertical surfaces, as its very short legs prevent it from perching.

Distribution

The Himalayan swiftlet breeds across the Himalayas, extending to Bangladesh, Myanmar, and Thailand. Some populations migrate, with altitudinal movements observed in the nominate race, which breeds up to 4,500 m but winters at lower altitudes between 900 and 2,750 m.

Behaviour

The Himalayan swiftlet is a colonial breeder and monogamous, with both partners sharing nestling care. It constructs a tiny cup nest from saliva and moss on vertical cave walls. This aerial insectivore forages during the day and returns to roost at night, often descending to lower elevations in poor weather or evening to feed over cultivated land. It is gregarious, forming flocks typically around 50 individuals, but sometimes up to 300.

Song & Calls

The swiftlet's vocalizations include a twittering "chit-chit" when roosting and a piercing "teeree-teeree-teeree" call. It also uses echolocation clicks to navigate in the dark, with the clicks becoming more rapid as light diminishes.

Breeding

Breeding occurs in caves where the male swiftlet builds the nest. The clutch consists of two white eggs, and the nests may be in close proximity within the colony.

Similar Species

In the southern part of its range, the Himalayan swiftlet can be difficult to distinguish from other Collocalia swiftlets.

Diet and Feeding

The Himalayan swiftlet feeds on insects caught in flight, leaving its roost during the day to forage and returning at night.

Conservation status

The Himalayan swiftlet is classified as Least Concern, although the Volcano swiftlet subspecies, if recognized as separate, is near-threatened due to its restricted habitat on active volcanoes in Java.

References

• BirdLife International (2017). "Aerodramus brevirostris". IUCN Red List of Threatened Species. 2017.
• Chantler and Driessens, Swifts.
• Grimmett, Inskipp and Inskipp, Birds of India.
• Robson, Craig A Field Guide to the Birds of Thailand.