Salangans

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Salangans
Blacknestsalangans (Aerodramus maximus)

Blacknestsalangans ( Aerodramus maximus )

Systematics
Class : Birds (aves)
Order : Sailor birds (Apodiformes)
Family : Sailors (Apodidae)
Tribe : Salangans
Scientific name
Collocaliini
Bonaparte , 1853

The salangans (Collocaliini) are a tribe within the family of sailors (Apodidae), to which nearly thirty species of birds are counted. Salangans occur in India , Southeast Asia , Australia and on the islands of the Indian Ocean and the Southwest Pacific . The salangans are very small to small sailors, the dwarf salangan ( Collocalia troglodytes ) as the smallest species has a body length of 9 centimeters, the giant salangan ( Hydrochous gigas ) as the largest species with a body length of 16 centimeters is slightly larger than central European swallows . Some species of salangan have the ability to echolocation, which is unusual for birds .

Edible bird nests

Most types of yachtsmen use saliva to build their nests, this behavior is most pronounced in the salangans. The white- nest salangan ( Aerodramus fuciphagus ) builds its nest exclusively from saliva. These almost white nests that look like water glass are the most popular "edible swallow nests", the essential ingredient in swallow's nest soup . But also the so-called black nests built by the black nestsalangans ( Aerodramus maximus ), which in addition to saliva mainly consist of feathers, are considered a delicacy. The popularity of these bird nests calls for measures to protect these species.

Breeding sites and echolocation

Most species of salangans breed in large colonies in dark caves, some on the coast, some inland. The colonies are sometimes huge, the number of individuals nesting in the Niah caves in the Malaysian state of Sarawak was estimated at over two million in 1931, but in 1999 the population had collapsed to around 300,000 due to the culinary exploitation of the nests.

Some of the salangan species have well developed echolocation skills . This is a very unusual ability in birds, which, apart from salangans, is only found in the South American fat swallow ( Steatornis caripensis ). In contrast to bats , the salangans apparently do not need this ability to localize prey in the air, but echolocation gives them the opportunity to nest in dark caves. In addition, this enables them to hunt insects for longer in the evening without having a problem looking for the nesting site in great darkness.

Systematics

The system of salangans is extremely controversial. In 1937 Ernst Mayr described it as the most difficult problem in bird taxonomy . Originally, all salangans were assigned to a single genus, namely Collocalia . Subsequently, divisions to several genera were discussed, and the species were rearranged several times - based on external characteristics and differences in breeding biology - until a division of the Salangans into three genera made by RK Brooke in 1970 found relatively broad recognition. This division has also been rejected by some authors in the meantime, but has been confirmed by some molecular genetic investigations carried out since 2003 . These studies, which were carried out using the mitochondrial cytochrome b gene segment, among other things, also prove that the salangans are monophyletic .

In the genus Collocalia, which originally comprised all species, there remained the sailors with shiny plumage, which do not have the ability to echolocate. The genus Hydrochous only includes the giant salangans that breed at waterfalls . The remaining species, which have a non-shiny, gray plumage, form the genus Aerodramus . These species have the ability to echolocation.

Another contradiction appeared, as has been demonstrated that the genus Collocalia counting Zwergsalangane ( C. troglodytes ) has the ability to echolocation. This property has lost its outstanding importance for differentiating between the genera Aerodramus and Collocalia . In 2005, a group of researchers led by Henri Thomassen suspected that echolocation in the dwarf alangana was caused by convergent evolution . Although the monophyly of Aerodramus and Collocalia was also confirmed in these investigations, the authors considered reuniting all salangans in one genus, as there is no longer any clear external characteristic to differentiate them.

An additional controversial aspect is the classification of the genus Schoutedenapus , about which very little is known. Due to their external similarity, the two species of this genus were originally assigned to the genus Apus . Due to their different toe arrangement -  anisodactyl instead of pamprodactyl as with the other Apus species  - the species were placed in a separate genus, namely Schoutedenapus . The assignment of this genus is difficult due to contradicting characteristics, so an assignment to the subfamily Cypselodinae was considered in addition to the assignment to the Apondini tribe . The sound utterances of the mouse swift, in turn, resemble the click sounds of the echolocating salangans, so that the genus Schoutedenapus is currently usually assigned to them due to a lack of sensible alternatives.

A distinction is usually made between the following genera:

literature

  • del Hoyo, Elliot, Sargatal (Eds.): Handbook of the Birds of the World . Volume 5: Barn-Owls to Hummingbirds . Lynx Edicions, 1999, ISBN 84-87334-25-3
  • David Lack : Swifts in a Tower . Chapman & Hall 1973; ISBN 0-412-12170-0
  • Phil Chantler, Gerald Driesses: A Guide to the Swifts and Tree Swifts of the World. Pica Press, Mountfield 2000, ISBN 1-873403-83-6

Individual evidence

  1. ↑ Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Pages 120–153, see literature
  2. ↑ del Hoyo et al. (1999): Handbook of the birds of the world . Page 405f, see literature
  3. ^ A b 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 )
  4. ↑ David Lack: Swifts in a Tower . Pages 23–35
  5. ↑ a b c Thomassen et al. (2005): 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
  6. ↑ del Hoyo et al. (1999): Handbook of the birds of the world . Page 391, see literature
  7. ↑ Thomassen et al. (2003): A new phylogeny of swiftles (Aves: Apodidae) based on cytochrome-b DNA . In: Molecular Phylogenetics and Evolution . Volume 29, pages 86-93 doi : 10.1016 / j.ympev.2005.05.010
  8. ↑ del Hoyo et al. (1999): Handbook of the birds of the world . Page 389f, see literature
  9. ↑ Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 24, see literature