Swiftlet

Schwarznestsalangane ( Aerodramus maximus)

The swiftlets ( Collocaliini ) are a tribe within the family of sailors ( Apodidae ), are expected to nearly thirty species of birds. Swiftlets are found in India, Southeast Asia, Australia and the islands of the Indian Ocean and the Southwest Pacific. The swiftlets are very small to small sailors who Zwergsalangane ( Collocalia troglodytes ) as the smallest species has a body length of 9 centimeters, the Riesensalangane ( Hydrochous gigas) is slightly larger than Central European swallows as largest species with a body length of 16 centimeters. Some Salanganenarten have the unusual ability for birds to echolocation.

Edible bird's nests

Most sailors types use saliva to build the nest, this behavior is most clearly pronounced in the swiftlets. The Weißnestsalangane ( Aerodramus fuciphagus ) builds its nest entirely of saliva. This almost white and as water glass looking nests are the most popular " edible swallows' nests ", the essential ingredient of bird's nest soup. But by the Schwarznestsalanganen ( Aerodramus maximus) built so-called black nests that consist mainly of salivary made ​​of feathers, are considered a delicacy. The popularity of these birds' nests makes measures to protect these species required.

Hatcheries and echolocation

Most species of swiftlets breed in large colonies in dark caves, some on the coasts, others inland. The colonies are sometimes huge, the number of individuals of nesting in the Niah Caves in the Malaysian state of Sarawak Salanganen was in 1931 estimated at over two million, in 1999 the stock was, however, due to the culinary utilization of nests plummeted to about 300,000.

Some of the Salanganenarten have well-developed skills for echolocation. This is a very unusual ability in birds, which can be found except for the swiftlets only during the South American fat Schwalm ( Steatornis caripensis ). In contrast to the bats Salanganen this ability obviously do not need to locate prey in the air, but echolocation allows them to nest in dark caves. Moreover, they are thus able to go longer at night hunting for insects without having a problem when searching for the nest site in great darkness.

System

The systematics of swiftlets is highly controversial. Ernst Mayr described it in 1937 as the most difficult problem of the taxonomy of birds. Originally, all swiftlets a single genus were assigned, namely Collocalia. In the following time allocations were discussed at several genera, and species have been - on external characteristics and differences in breeding biology based - repeatedly resorted to 1970, an examination by RK Brooke division of swiftlets found relatively wide recognition to three genera. Also, this division has since been rejected by some authors, but confirmed by guided by some since 2003, molecular genetic studies. This, among other things carried out on the basis of the mitochondrial cytochrome b gene segment studies also show that the swiftlets are monophyletic.

In the originally encompassing all types genus Collocalia the sailors remained with shiny feathers that do not have the ability to echolocation. The genus Hydrochous belongs only to the brooding waterfalls Riesensalangane. The remaining species, which have a non-glossy, gray plumage, form the genus Aerodramus. These species have the ability to echolocation.

Another contradiction arose when it was shown that the counting to the genus Collocalia Zwergsalangane (C. troglodytes) has the ability to echolocation. For this property has lost its outstanding importance for distinguishing between genres Aerodramus and Collocalia. A research group led by Henri Thomassen conjectured in 2005 that echolocation is incurred in the Zwergsalangane by convergent evolution. Although the monophyly of Aerodramus and Collocalia was also operated in these studies, the authors were considering all swiftlets to reunite in a genus, since there is now no clear outward sign more to distinguish.

An additional aspect is the controversial position of the genus Schoutedenapus, very little is known about the. Because of their superficial similarity, the two species of this genus were originally assigned to the genus Apus. Due to their different arrangement toes - anisodactyl place as in the other species Apus pamprodactyl - the types were placed in a separate genus, namely Schoutedenapus. The allocation of this kind is difficult because of conflicting characteristics, as well as an assignment to the subfamily Cypselodinae has been considered in addition to the assignment to the tribe Apondini. The vocalizations of the mouse sailor in turn resemble the click sounds of echolocating swiftlets, so that the genus Schoutedenapus lack of meaningful alternatives usually this is currently assigned.

The following genera are usually distinguished:

• Tribus: swiftlets ( Collocaliini ) Genus: Collocalia with 3 types
• Genus: Aerodramus with 22 species
• Genus: Hydrochous with the only kind Riesensalangane (H. gigas)
• Genus: Schoutedenapus with 2 types