The Himalayan swiftlet (''Aerodramus brevirostris'') is a small

swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIF ...

. It is a common colonial breeder in the

Himalayas The Himalayas, or Himalaya ( ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the Earth's highest peaks, including the highest, Mount Everest. More than list of h ...

and

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

. Some populations are migratory. This

swiftlet Swiftlets are birds from the four genera ''Aerodramus'', ''Collocalia'', ''Hydrochous'' and ''Schoutedenapus'', which form the tribe (biology), tribe Collocaliini within the swift (bird), swift family (biology), family Apodidae. The group contain ...

was formerly placed in the genus ''Collocalia''. Two of its five subspecies are frequently given full species status, ''A. b. rogersi'' as the Indochinese swiftlet, ''Aerodramus rogersi'', and the isolated

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

n form ''A. b. vulcanorum'' as the Volcano swiftlet, ''Aerodramus vulcanorum''.

Description

This 13–14 cm long swiftlet has swept-back wings that resemble a crescent or a

boomerang A boomerang () is a thrown tool typically constructed with airfoil sections and designed to spin about an axis perpendicular to the direction of its flight, designed to return to the thrower. The origin of the word is from Australian Aborigin ...

. 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 Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...

Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...

and

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

. 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 China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, and winters in southwestern Thailand and the

Malay Peninsula The Malay Peninsula is located in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area contains Peninsular Malaysia, Southern Tha ...

. 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 Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...

. This is a small, pale-rumped race. *''A. b. vulcanorum'' the volcano swiftlet, breeds in Java,

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

on volcanic peaks. It has dark underparts and an indistinct pale grey rump. Over much of its range, this is the only swift, but in the south of its breeding area and much of its wintering range it can be very difficult to distinguish this species from other ''Collocalia'' swiftlets.

Voice and echolocation

The Himalayan swiftlet has a twittering ' roosting call, and also has a piercing ' call. What distinguishes many, but not all, swiftlet species from other swifts and indeed almost all other birds (the

oilbird The oilbird (''Steatornis caripensis''), locally known as the , is a bird species found in the northern areas of South America including the Caribbean island of Trinidad. It is the only living species in the genus ''Steatornis'', the family Stea ...

being an exception) is their ability to use a simple but effective form of echolocation to navigate through the darkness of the

cave Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance undergrou ...

s where they roost at night and breed. With the present species, at least ''vulcanorum'' is known to echolocate. Unlike bats, the swiftlets make clicking noises for echolocation that are well within the human range of hearing. Two broadband pulses are separated by a slight pause. The length of the pause shortens as light becomes poorer. The clicks are followed by the twittering call when the bird is approaching its nest. Echolocation was used to separate the former genus ''Aerodramus'', which was thought to contain the only echolocating swiftlets. from ''

Collocalia ''Collocalia'' is a genus of Swift (bird), swifts, containing some of the smaller species termed "swiftlets". Formerly a catch-all genus for these, a number of its former members are now normally (though not by all authors) placed in ''Aerodramus ...

'', but the discovery that the

pygmy swiftlet The pygmy swiftlet (''Collocalia troglodytes'') is a species of Swift (bird), swift in the family Apodidae. It is Endemism, endemic to the Philippines. Its natural habitat is tropical moist lowland forests. At under , it is the world's smallest ...

, ''Collocalia troglodytes'', also echolocates led to some taxonomists merging the two genera.

Behaviour

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 Nepal, officially the Federal Democratic Republic of Nepal, is a landlocked country in South Asia. It is mainly situated in the Himalayas, but also includes parts of the Indo-Gangetic Plain. It borders the Tibet Autonomous Region of China Ch ...

and 2200m in central

Bhutan Bhutan, officially the Kingdom of Bhutan, is a landlocked country in South Asia, in the Eastern Himalayas between China to the north and northwest and India to the south and southeast. With a population of over 727,145 and a territory of , ...

, 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 Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...

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 Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tai ...

and small breast muscles.

Status

This species is common and widespread, but the volcano swiftlet, if considered a separate species, is near-threatened. It occurs only on active

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

s in Java, with four definite sites and five likely but unconfirmed sites. Birdlife International estimates a total of under 400 birds for the known localities. Since this form nests in crater crevices, and all known localities are active volcanoes, colonies are believed to be susceptible to periodic extinction.

References

Birdlife International
* Chantler and Driessens, ''Swifts'' * Grimmett, Inskipp and Inskipp, ''Birds of India'' *Robson, Craig ''A Field Guide to the Birds of Thailand'' {{Taxonbar, from=Q1259817

Himalayan swiftlet The Himalayan swiftlet (''Aerodramus brevirostris'') is a small swift. It is a common colonial breeder in the Himalayas and Southeast Asia. Some populations are migratory. This swiftlet was formerly placed in the genus ''Collocalia''. Two of i ...

Birds of the Himalayas Birds of Eastern Himalaya Birds of Central China Birds of Yunnan Birds of Myanmar