White salangans
| White salangans | ||||||||||||
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White-nest salangans in Balikpapan , in the Indonesian part of the island of Borneo |
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| Scientific name | ||||||||||||
| Aerodramus fuciphagus | ||||||||||||
| ( Thunberg , 1812) |
The white-nest salangana ( Aerodramus fuciphagus , Syn .: Collocalia fuciphaga ) is a species of bird from the family of the sailors (Apodidae). With a length of twelve centimeters, it is a medium-sized representative of the salangans . Their quite extensive, but highly fragmented range is in Southeast Asia . The species is one of the salangan species that have the ability to echolocation , which enables the birds to visit their nesting sites in caves.
The white nestsalangana is best known for its whitish nests, which consist almost exclusively of the saliva of birds. These nests are the most important ingredient in swallow's nest soup , a delicacy in Chinese cuisine . Because of their purity, the nests of this species are among the most sought-after.
features
Appearance
The body length is twelve centimeters, the weight between 10 and 15 grams. The entire upper side is quite uniformly dark black-brown, only the rump is lighter and turns gray; in some individuals, however, the color difference is quite slight. The underside is predominantly gray-brown and lighter than the upper side, the throat is the lightest, from the chest to the rump the color is more brown than gray. The under tail-coverts are darker, but show a pale, gray edge. The colouration 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 medium and small arm covers. Both sexes look the same.
The tail fork is comparatively clear with an incision between 5 and 8 millimeters. This is also the best distinguishing feature to black nest salangans ( Aerodramus maximus ) and moss nest salangans ( Aerodramus salangana ), especially to their sympatric dark subspecies , which are very difficult to distinguish in the field.
Vocalizations
Many different calls were made especially with the subspecies A. f. germani and it can be assumed that the same applies to all other subspecies. The most striking call is a loud, metallic-sounding “zwing”, which is reminiscent of the calls of tree swifts . A series of “chip” sounds or a fuller “krip” can be heard more often.
White-nest salangans have the ability to echolocate . They use them to look for their nesting sites in the darkness of caves. A short sequence of two clicks in the frequency range between 3.0 and 7.3 kilohertz is typically used for echolocation . The first is a little shorter, the second a little longer than three milliseconds, the pause between two clicks is around 1.2 milliseconds. Simple clicks can also be heard about 25 percent of the time.
distribution
The white-nest salangan has a fairly extensive, but highly fragmented range in Southeast Asia . On the Southeast Asian mainland, the species occurs in a coastal strip from Khlong Nakha in the west of the Malay Peninsula via Singapore in the south to the Khao Sam Roi Yot National Park on the east coast, from around 7 ° north latitude south also inland, and also on many offshore areas Islands. There is also an isolated occurrence in Bangkok . Another distribution area on the mainland is in a coastal strip of Cambodia in the west over the Mui-Ca-Mau National Park in the south of Vietnam and the Vietnamese east coast up to the height of Hainan . The species can also be found on the southeast coast of Hainan, as well as on the Côn Đảo archipelago in southeast Vietnam.
The species is also found on almost all islands of the Sunda Arc , starting with the Andaman and Nicobar Islands in the northwest, over the large islands of Sumatra and Java and the neighboring islands to the Lesser Sunda Islands , including some islands in the Flores Sea , possibly also in southern Sulawesi .
The distribution in Borneo has hardly been researched, possibly the species is widespread here. The species has only been found in individual places on the island, for example in the Sarawak Delta . Off Borneo, the white nest salangan occurs on some islands on the north coast as well as off Sandakan and Kuching . It is also found on the Anambas Islands between Borneo and the Malay mainland.
From the Philippines , the island of Palawan and the island groups of Cagayan , Calamian and Cuyo to the northeast are settled. The species may also inhabit the Sulu Archipelago in the southwest of the Philippines.
The white-nest salangane is a resident bird in the entire distribution area .
habitat
On the Andaman and Nicobar Islands , behavior typical of salangans was observed: White- nest salangans hunt over mangroves , forests , rubber plantations or other cultural landscapes. The habitat spectrum of the white-nest salangans is quite large, from small coastal islands to lowlands in the interior to mountain regions, on Sumatra up to 2800 meters altitude. Occasionally the species can be seen far out in the open sea.
Behavior and food acquisition
White nestsalangans are very sociable. The species can be found in large, mixed schools with other sailors and swallows . The foraging for food takes place during the day, it is most intensive at late dusk. On the hunt for flying small animals that are caught in the air, the birds fly at an average height of almost 60 meters.
A study of sympathetic sailors in the Gomantong Caves near Sandakan in Malaysia showed that the white-nest salangan preferred significantly smaller prey compared to the other species, even compared to the much smaller bright-headed salangan ( Collocalia esculenta ). The food composition of the collected in the throat pouch food bales of edible-nest swiftlet corresponded apart from the size strongly of the Moosnestsalangane in continuous over the rainforest foraging Weißnestsalanganen all less than 40 percent was the food components to skin and Diptera , further essential constituents in a proportion 5-10 Percent were constant-winged birds , beetles and arachnids . In contrast, the composition of the similarly sympathetic black nest salangana is significantly different with an almost 90 percent proportion of hymenoptera.
Reproduction
The breeding seasons differ depending on the climatic conditions within the distribution area. In many regions nest building takes place mainly in March and April, but in some regions the species breeds throughout the year. The nests are often in caves within huge breeding colonies. But nests can also be found on buildings, and some subspecies even breed primarily near humans. The building damage caused by this is gladly accepted because of the valuable nests, for example on Belitung , where over a hundred breeding pairs nested directly above the kitchen of a Chinese restaurant .
The nest is a self-supporting half-shell that is attached to cave walls or other vertical surfaces like a console. The diameter is about 6, the height 1.5 centimeters, the weight is about 14 grams. The nests are whitish and appear slightly transparent. They consist almost exclusively of pure, thickened saliva with little or no other components. This is why the protein-rich nests of the species are among the most sought-after ingredients in swallow's nest soup, and the ruthless use of the nests is a problem. If the birds are forced to build replacement nests, these are less pure and contain more other components. Nest building takes between 39 and 55 days.
The clutch consists of two white, long oval, barely shiny eggs, the average dimensions are 20.2 × 13.6 millimeters. In one colony near Penang in Malaysia, an average incubation time of around 25 days was determined; it was slightly shorter for the second egg. The nestling period averaged 43 days. An average of 0.9 young flew out per brood.
Existence and endangerment
In large parts of the distribution area, the white-nest salangana is not uncommon, in parts it is even very common. Due to the utilization of the nests for the swallow's nest soup , however, there are significant regional drops, which can also be seen in the decreasing yield of these nests. A study conducted on the Nicobar Islands examined the populations in 36 caves and estimated around 1,500 breeding pairs in 1995, an 85 percent decline since 1987.
BirdLife International estimates the size of the range at approximately 1.4 million square kilometers and does not consider the decline in populations to be so dramatic as to classify the species as threatened.
Systematics
Originally all salangans were assigned to the genus Collocalia . In 1970 the salangans were split into three genera; all species with the ability to echolocation were placed in the genus Aerodramus . Since then, however, it has been proven that the dwarf alangans ( C. troglodytes ) , which belong to the genus Collocalia , are also echolocating species. However, the monophyly of the species previously assigned to the genus Aerodramus has also been confirmed by molecular genetic studies. According to these studies, the moss nest salangans ( Aerodramus salangana ) is the sister taxon of the white nest salangans .
A total of eight subspecies are distinguished. Here, A. f. germani together with the subspecies A. f. amechanus is often seen as an independent species that has the German common name German-Salangane or Oustalet-Salangane.
- A. f. fuciphagus : The nominate form occurs in Java including the Kangean Islands and Belitung , and also on the western Lesser Sunda Islands , Bali , the islands of the Flores Sea and Jampea .
- A. f. inexpectatus : This subspecies is native to the Andaman and Nicobar Islands and is slightly smaller than the nominate form.
- A. f. dammermani : This subspecies, which can be found on Flores and the Lesser Sunda Islands , was determined on the basis of a single, more closely examined individual, the rump is only slightly paler than the coat, it is uncertain whether there are any other differences to the nominate form, and if so, which ones.
- A. f. micans : This subspecies occurs on Sumba , Sawu , Timor and the Lesser Sunda Islands . The plumage is paler and more gray than in the nominate form, the contrast between rump and coat is relatively weak.
- A. f. vestitus : The subspecies occurring on Sumatra and Borneo largely corresponds to the nominate form in terms of pattern, the upper side is somewhat darker. The representatives of this subspecies show considerable individual variations.
- A. f. perplexus : This subspecies is on the east front of the Indonesian part of Borneo upstream Maratua Archipelago before arriving at the Derawan Islands belongs. The rump barely stands out from the rest of the top, the sheen on the balance and control feathers turns purple.
- A. f. germani : This subspecies occurs on Hainan , on the coasts of Vietnam , Cambodia , Thailand and on the Mergui Archipelago , as well as in parts of the Malay Peninsula and in the south of the Philippines . The underside is extremely pale, the rump is very broad and almost white.
- A. f. amechanus : The distribution area of this subspecies closes on the Malay Peninsula south of that of A. f. germani to which this subspecies resembles; the rump is grayer than in A. f. germani .
swell
literature
- Phil Chantler, Gerald Driessens: A Guide to the Swifts and Tree Swifts of the World. Pica Press, Mountfield 2000, ISBN 1-873403-83-6 .
- Joseph del Hoyo, Andrew Elliot, Jordi Sargatal (Eds.): Handbook of the Birds of the World. Volume 5: Barn-owls to Hummingbirds. Lynx Edicions, 1999, ISBN 84-87334-25-3 .
Individual evidence
- ↑ This and all information not specially marked are taken from the following source: Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 150ff, see literature
- ^ CM Francis: The management of edible birds nest caves in Sabah. Sabah Forestry Department, Sandakan 1987
- ↑ 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)
- ^ SA Lourie, DM Tompkins: The diets of Malaysian swiftlets. In: Ibis. 142: 596-602, 2000. doi : 10.1111 / j.1474-919X.2000.tb04459.x .
- ↑ BirdLife International: Species Factsheet - Edible-nest Swiftlet ( Aerodramus fuciphagus ) . Retrieved October 4, 2009.
- ^ Henri A. Thomassen, Robert-Jan den Tex, Merijn AG de Bakker, G. David E. Povel: Phylogenetic relationships amongst swifts and swiftlets: A multi locus approach. In: Molecular Phylogenetics and Evolution. 37, 2005, pp. 264-277, doi : 10.1016 / j.ympev.2005.05.010 .
- ↑ German-Salangane ( Aerodramus germani ) at Avibase
Web links
- Aerodramus fuciphagus in the endangered Red List species the IUCN 2009. Posted by: BirdLife International, 2008. Accessed on October 1 of 2009.
