Himalayan Swiftlet
Encyclopedia
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 its five subspecies are frequently given full species status, A. b. rogersi as the Indochinese Swiftlet, Aerodramus rogersi, and the isolated Java
n form A. b. vulcanorum as the Volcano Swiftlet, Aerodramus vulcanorum.
. 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.
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.
What distinguishes many, but not all, swiftlet species from other swifts and indeed almost all other birds( the Oilbird
being an exception) is their ability to use a simple but effective form of echolocation
to navigate in through the darkness of the cave
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 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 Aerodramus genus, which was thought to contain the only echolocating swiftlets. from Collocalia
, but the discovery that the Pygmy Swiftlet
, Collocalia troglodytes, also echolocates led to some taxonomists merging the two genera.
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 of 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.
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.
Swift
The swifts are a family, Apodidae, of highly aerial birds. They are superficially similar to swallows, but are actually not closely related to passerine species at all; swifts are in the separate order Apodiformes, which they share with hummingbirds...
. It is a common colonial
Bird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...
breeder in the Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
. Some populations are migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
.
This swiftlet
Swiftlet
Swiftlets are birds contained within the four genera Aerodramus, Hydrochous, Schoutedenapus and Collocalia. They form the Collocaliini tribe within the swift family Apodidae. The group contains around thirty species mostly confined to southern Asia, south Pacific islands, and northeastern...
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
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
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 boomerangBoomerang
A boomerang is a flying tool with a curved shape used as a weapon or for sport.-Description:A boomerang is usually thought of as a wooden device, although historically boomerang-like devices have also been made from bones. Modern boomerangs used for sport are often made from carbon fibre-reinforced...
. 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 BangladeshBangladeshBangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
, MyanmarMyanmarBurma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....
and ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. 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 ChinaChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, and winters in southwestern Thailand and the Malay PeninsulaMalay PeninsulaThe Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...
. 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 LaosLaosLaos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...
. This is a small, pale-rumped race. - A. b. vulcanorum the Volcano Swiftlet, breeds in Java, IndonesiaIndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
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 chit-chit roosting call, and also has a piercing teeree-teeree-teeree call.What distinguishes many, but not all, swiftlet species from other swifts and indeed almost all other birds( the Oilbird
Oilbird
The Oilbird , also known as Guácharo, is a bird found in the northern areas of South America . They are nocturnal feeders on the fruits of the Oil Palm and tropical laurels, and are the only nocturnal fruit eating birds in the world...
being an exception) is their ability to use a simple but effective form of echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
to navigate in through the darkness of the cave
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
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 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 Aerodramus genus, which was thought to contain the only echolocating swiftlets. from Collocalia
Collocalia
Collocalia is a genus of swifts, containing some of the smaller species termed "swiftlets". Formerly a catch-all genus for these, a number of its erstwhile members are now normally placed in Aerodramus....
, but the discovery that the Pygmy Swiftlet
Pygmy Swiftlet
The Pygmy Swiftlet is a species of swift in the Apodidae family.It is endemic to the Philippines.Its natural habitat is subtropical or tropical moist lowland forests. At under 9 cm , it the world's smallest swift....
, 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 NepalNepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
and 2200m in central Bhutan
Bhutan
Bhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...
, 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 of saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
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 feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...
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 volcanoVolcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
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.