Black nest salangans

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Black nest salangans
Black nest salangans (Aerodramus maximus) in Upper Peirce Reservoir, Singapore

Black nest salangans (Aerodramus maximus) in Upper Peirce Reservoir , Singapore

Systematics
Class : Birds (aves)
Order : Sailor birds (Apodiformes)
Family : Sailors (Apodidae)
Tribe : Salangans (Collocaliini)
Genre : Aerodramus
Type : Black nest salangans
Scientific name
Aerodramus maximus
( Hume , 1878)

The black nest salangan ( Aerodramus maximus , Syn .: Collocalia maxima ) is a species of bird from the family of the sailors (Apodidae). With a body length of 14 centimeters, it is one of the larger species of salangan . The plumage is predominantly gray-brown, the tail slightly forked. The distribution area is in Southeast Asia , mainly on the Malay Peninsula and the Sunda Islands . The species has the ability to echolocation , which enables it to visit the breeding colonies lying in caves.

The nests of the species belong to the so-called " edible swallow nests ". But they are not as popular as the nests of the white nest salangans ( Aerodramus fuciphagus ), which consist almost exclusively of saliva , since black nest salangans also use feathers as a building material in not inconsiderable amounts.

features

Appearance

The body length is 14 centimeters, the weight between 14 and 21 grams. Values ​​between 126 and 135 millimeters were determined for the wing length. The tail length is between 50 and 58 millimeters. The tail fork is indistinct, the depth of the incision is 11 to 15 percent of the tail length.

The upper side including the top of the head is predominantly colored black-brown and shiny. Only the rump is a little paler, but in some individuals it hardly stands out from the rest of the top. The lighter, gray underside is lightest on the throat, from the breast the striped pattern formed by the feather shafts becomes clear: The gray color gradually darkens from the breast to the tail, the under tail covers are dark gray and show a light border. The top of the wings is very uniformly glossy black, with the outer tangs being the darkest and showing the most gloss. The color of the underside of the wing is typical of salangans , the wing feathers and the large arm covers are paler and form a contrast to the much darker middle and small arm covers. Both sexes look the same.

The relatively indistinct tail fork is the best differentiator for sympatrically occurring edible-nest swiftlet , which also is somewhat smaller. In many cases, the pale rump, which stands out more clearly, is a useful criterion for distinguishing the two species. In the extreme northwest of the distribution area of ​​the black nest salangan, it occurs together with the Himalayan salangan ( Aerodramus brevirostris ), the latter also winters on the Malay Peninsula and on Sumatra , where both species meet. The Himalayan langan also has a deep forked tail and appears slimmer. When determining the species “in the hand”, the strong fletching of the legs is a good distinguishing feature; in the black nest salangana it covers practically the entire tarsometatarsus . With white nest or Himalayan langans, the fletching never reaches that far down, although there are great individual and subspecies-specific differences.

Vocalizations

A chattering "chit-chit" can be heard near the nesting site, as well as a piercing "tiiii-tiiii-tiiii". The vocalizations correspond to those of the Himalayan langans.

Black -nest salangans have the ability to echolocate , with the help of which they seek their nesting sites in the darkness of caves. A short sequence of two clicks is typically used for echolocation, which is in the frequency range between 1.9 and 6.8  kilohertz . The duration of a click is between 6 and 7 milliseconds, the first is a little shorter on average, and the pause between the two clicks is around 1.1 milliseconds. Simple clicks can also be heard about 46 percent of the time.

distribution

Distribution area of ​​the black nest salangans. Areas with questionable occurrences are indicated by question marks

The black nest salangan occurs mainly on the Malay Peninsula and the Sunda Islands . On the west coast of the Malay Peninsula they can be found in Tanintharyi in Myanmar and from the southern tip to a little north of Phuket and also on some offshore islands. On the east coast there are deposits in Terengganu , Pahang and Johor . The only known colony in the interior of the Malay Peninsula is in Kuala Lumpur .

The exact distribution on Sumatra is unclear, as relatively few breeding colonies are known; they are almost exclusively on the west coast and on the offshore islands. On some offshore islands in the west of Sumatra, the black nest lamb can be found, as well as on individual islands of the Strait of Malacca . The entire west of Java is also populated. The species has been found in some parts of Borneo , particularly in Kalimantan , the Indonesian part of the island and on the coast in the south and southeast of Borneo. The black nest salangans also breed on the Labuan and Anambas Islands . Since 1981 broods have been found in caves in southeast Vietnam in the province of Khánh Hòa and on the offshore islands. There have also been sightings on the Philippine island of Palawan , but these may be random visitors .

The black nest salangan is a resident bird in the entire distribution area , but the sightings on Palawan are an indication that sporadic migrations could occur.

habitat

Blacknestsalangans occur in Southeast Asia from the coast to the mountains, the highest known habitat is at an altitude of 1830 meters. When foraging for food, the birds look for very different habitats. These mainly include open terrain, but the birds can also be observed regularly within dense forests below the treetops. The airspace over inhabited areas and islands off the coast are also used for foraging.

The caves used for breeding are almost exclusively limestone caves . In order to avoid interspecific competition, the black nest salangans and the sympatric white nest salangans prefer different areas of the cave, whereby the nature of the walls seems to be an essential factor. In contrast to the white nest salangana, the black nest salangane only breeds in natural caves, there are no settlements in special breeding farms.

Behavior and food acquisition

Blacknestsalangans are extremely sociable. Like most salangans, the species is particularly active at dawn and dusk. Large schools can then be seen near the entrances to the burrows used for nesting. Compared to sympatric occurring Moosnestsalanganen ( Aerodramus salangana ) hunt Schwarznestsalanganen longer at higher altitudes and further away from the nesting flying small animals - both types, however, are also observed in mixed shoals.

It is speculated that the species might not also look for food in the dark, as some termites and ants swarm between sunset and complete darkness. What is certain is that echolocation itself is not an advantage when hunting insects, but it does allow you to visit the caves after dark.

The food spectrum of the black-nest swiftlet differs significantly from that of occurring in the same habitat white and Moosnestsalangane, in contrast to these, there is the food to almost 90 percent of hymenoptera (almost exclusively flying ants) and to a much lesser extent from Diptera , Gleichflüglern , beetles and arachnids . The prey animals are larger than with the other salangans, the variety of the captured species is significantly less.

Reproduction

"Harvested" nest of the black nest salangans from the Madai Cave in Sabah

The species breeds in colonies that lie in caves, often together with the white-nest , moss-nest or shiny-headed salangan ( Collocalia esculenta ). The laying times are quite different due to the different climatic conditions within the distribution area. For example, in the Niah caves in northwest Borneo , the breeding takes place between September and April where the birds are not disturbed by the utilization of the nests. The young mainly fly out in March and April, i.e. in the first months with less rainfall, when the food situation becomes more favorable again. If the nests are removed at a late point in time, the reproductive period can lengthen slightly beyond the natural duration. In the Gomantong Caves on the east coast of Borneo near Sandakan , the breeding season is between February and September. In the south-east of Vietnam , the black-nest salangan begins to build nests at the beginning of December; in the event of a loss of nest due to exploitation, replacement nests will be built by October.

The nest is a flat, self-supporting half-shell. It consists of feathers and is glued with transparent, hardening saliva and attached to the wall. Herbal ingredients are not used. It takes between 35 and 127 days to build the nest. It mainly takes place at night, with both partners taking turns building the nest. After a construction phase, intensive cleaning is very typical. During studies in Singapore it was found that around 700 feathers are built into a nest, which make up around 10 percent of the dry matter. These are mainly contour feathers , cover feathers or half-down feathers , swing springs or control feathers are rarely used. It can be assumed that the feathers come from the building bird itself; in any case, the moulting of all the black nest salangans examined coincided with the nest building phase.

The clutch consists of only one egg, the dimensions are on average 23.7 × 16.2 millimeters. In the event of a nest loss, replacement broods are the rule, in parts of the distribution area there are probably also second broods. The incubation period is between 24 and 32 days, the nestling period between 52 and 65 days, and the feeding frequency is comparatively low. Both sexes participate equally in the breeding business.

The ruthless culinary exploitation of the nests has a clear impact, in 1962 in the Niah caves a breeding success of only 17 percent was determined. In order to keep the effects on the populations low, there is a restriction in some regions that, with a few exceptions, the nests may only be "harvested" twice per season: once at the beginning of the breeding season, immediately after the first nest has been built, if possible before the eggs are laid, and also at the end, when the young have flown out. Even with this regulated recycling, a reduction in the breeding success can be ascertained, which fell from 92 to 76 percent in an investigation in the Gomantong caves . On the one hand, this is attributed to the fact that the construction of the replacement nests puts an energetic load on the birds, which can be seen, among other things, from the fact that no eggs were laid in three times as many replacement nests as the original nests. On the other hand, the time that can be used for brooding is shortened. The birds therefore have fewer opportunities for those replacement broods that are required for other reasons.

Existence and endangerment

In the Thai part of the distribution area and in the west of the Malay Peninsula , the black nest salangan is quite rare, in the other parts of the area it occurs frequently in certain areas. Due to the utilization of the nests for the swallow's nest soup , however, there are regionally major populations. For example, the population of black nest salangans in the Niah Caves in the Malaysian state of Sarawak has decreased from over 2 million in 1931 to around 300,000 in 1999. BirdLife International does not consider the population decline to be so dramatic that the species should be classified as threatened.

Systematics

Originally all salangans were assigned to the genus Collocalia . In 1970, RK Brooke divided the salangans into three genera, the ability to echolocation being the decisive criterion; all salangans with this ability were placed in the genus Aerodramus . But since it has been proven that the dwarf salangans ( C. troglodytes ) , which belong to the genus Collocalia , is also one of the echolocating species, the systematics within the salangans is open again.

Closest related to the black nest salangan is the subspecies vulcanorum of the Himalayan salangan , which some authors also consider as an independent species ( Aerodramus vulcanorum ) and thus the sister species of the black nest salangan.

Three subspecies are recognized.

  • At the. maximus ( Sharpe , 1879) : The distribution area of ​​the nominate form includes Tanintharyi , the Malay Peninsula, southeast Vietnam and parts of western Java .
  • At the. lowi ( Hume , 1878) : This subspecies occurs on Sumatra , Nias , in the north and west of Borneo , on the Labuan Islands in the west of Java and on Palawan . The rump is darker in color than in the nominate form. In western Java there is a clinical transition between A. m. lowi and the nominate form.
  • At the. tichelmani ( Stresemann , 1926) : This subspecies occurs in the southeast of Borneo. The subspecies is smaller than the nominate form and A. m. lowi , the rump is also paler than in A. m. lowi .

In the past, the populations in Tanintharyi and on the west coast of the Malay Peninsula were regarded as the fourth subspecies ( A. m. Robinsoni ), but these are now assigned to the nominate form.

literature

Individual evidence

  1. a b c d e f g h i j k l Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 148 ff., See literature
  2. a b c N. Kang, CJ Hails, JB Sigurdsson: Nest construction and egg-laying in Edible-nest Swiftlets Aerodramus spp. and the implications for harvesting. In: Ibis. 133: 170-177, 1991 ( doi : 10.1111 / j.1474-919X.1991.tb04828.x )
  3. ^ CM Francis: The management of edible birds nest caves in Sabah. Sabah Forestry Department, Sandakan 1987
  4. Hendrik A. Thomassen: Swift as sound. Design and evolution of the echolocation system in Swiftlets (Apodidae: Collocaliini). Leiden University, 2005 ( online ; PDF; 7.9 MB)
  5. ^ A b Craig Robson: Birds of South-East Asia. Page 64, New Holland Publishers, 2007, ISBN 978-1-84330-746-4
  6. Supaluck Viruhpintu, Kumthorn Thirakhupt, Art-Ong Pradatsundarasar, Pilai Poonswad: Nest-site Characteristics of the Edible-nest Swiftlet Aerodramus fuciphagus (Thunberg, 1812) at Si-Ha Islands, Phattalung Province, Thailand. In: The Natural History Journal of Chulalongkorn University. 2: 31–35, 2002 ( online  ( page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. )@1@ 2Template: Toter Link / www2.biology.sc.chula.ac.th  
  7. ^ SA Lourie, DM Tompkins: The diets of Malaysian swiftlets. In: Ibis. 142: 596-602, 2000. doi : 10.1111 / j.1474-919X.2000.tb04459.x .
  8. Lord Medway: The Swiftlets (Collocalia) of Niah Cave, Sarawak. Part 2. Ecology and the regulation of breeding. In: Ibis. 104: 228-245, 1962 ( doi : 10.1111 / j.1474-919X.1962.tb08648.x )
  9. ^ A b Daniel M. Tompkins: Impact of nest-harvesting on the reproductive success of black-nest swiftlets Aerodramus maximus. In: Wildlife Biology. 5: 45–48, 1999 ( online ; PDF; 2.5 MB)
  10. ^ Joseph J. Hobbs: Problems in the harvest of edible birds' nests in Sarawak and Sabah, Malaysian Borneo. In: Biodiversity and Conservation. 13: 2209–2226, 2004 ( doi: 10.1023 / B: BIOC.0000047905.79709.7f )
  11. BirdLife International: Species Factsheet - Black-nest Swiftlet ( Aerodramus maximus ) . Retrieved October 16, 2009.
  12. a b Thomassen et al .: Phylogenetic relationships amongst swifts and swiftlets: A multi locus approach . In: Molecular Phylogenetics and Evolution . Volume 37, 2005, pages 264–277, doi : 10.1016 / j.ympev.2005.05.010 .

Web links

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This version was added to the list of articles worth reading on April 6, 2010 .