Pygmy Swiftlet

The Zwergsalangane ( Collocalia troglodytes ) is a species of bird in the family of sailors ( Apodidae ). It is the smallest Salanganenart with a body length of 9 centimeters. The species is endemic to the Philippines. The plumage is mainly dark black brown, rump, it shows a narrow, strongly contrasting white stripes. The nesting sites of Zwergsalangane are located within caves. It has as many other Salanganen have the ability to echo detection, but is the only genus Collocalia enabled to Article

Features

Appearance

The body length is specified by 9 centimeters, the wing length is 86-96 mm. Zwergsalanganen weigh 4.5 to 6.8 grams, 5.4 grams on average. As a very small Salanganenart it is easy to determine with their dark, black brown top and narrow, but clearly contrasting white band in the region of the rump. Both wings and the tail indicates the type typical of the genus feathers shine. The bottom of the wings and tail are slightly lighter as compared to top, the middle and small coverts are clearly darkest parts of the feathers bottom. The underside of the body is very spotty, and especially between the upper abdomen and rump she is very bright throat and upper chest are gray-brown.

Most likely to be confused is the Zwergsalangane with almost as small, sympatric Glanzkopfsalangane. Partial show in the Philippines occurring members of this closely related species paler plumage parts in the region of the rump, but it still differs significantly from the strongly contrasting white band of Zwergsalangane.

Vocalizations

The vocalizations of Zwergsalangane be described as a gentle chirping.

Since the nesting of the species can 30 meters lie in the interior of caves was longer have guessed, the type could have the ability of echolocation. This was confirmed in 2004. This is the Zwergsalangane the only member of the genus Collocalia with this property. The Zwergsalangane used it two lying in the audible frequency range of people clicking sounds at short intervals, so-called " double clicks " like most other echolocating Salanganenarten that are all assigned to the genus Aerodramus. Also, the mean time interval between the two clicks is 16.9 milliseconds in the same range as for the Aerodramus species.

Dissemination

The Zwergsalangane occurs on almost all Philippine Islands, also in Palawan, but not quite in the southwest on the islands of the Sulu Archipelago. The species occurs in lowland very regularly, in the foothills of something rare. In the entire area of ​​distribution is the Zwergsalangane state bird.

Habitat

The predominantly occurring at lower altitudes species is often found near inland waters. Away from the water there is the Zwergsalangane on or near forests.

Behavior and food acquisition

Zwergsalanganen socialize and watch usually in smaller groups.

Like all sailors feed Zwergsalanganen of trapped air in the insects and arachnids. They start at medium altitude in search of food, they hunt in forest areas directly above the treetops. In more open terrain with only scattered trees they fly a little lower, but never directly on the floor. Syntopically occurring Glanzkopfsalanganen fly much lower in search of food. It appears that they are forced by competition from the Zwergsalanganen simultaneously present in this ecological niche, because in these areas without food competitors they occupied obviously the middle height range.

Reproduction

The beginning of the breeding season is in Mindanao in July, on Bohol and Negros in April. Nestlings were partially observed in September. The nest is a shallow, self-supporting half-shell, which are mounted on a cave wall or on walls of irrigation tunnels. It consists of vegetable materials, which are solidified with a considerable proportion saliva. There was discussion about whether the nests to the " edible swallows' nests " among others, which could not be known with certainty.

The nest is usually made of two eggs, the size is 16 x 10 millimeters.

System

Recent molecular genetic studies have shown that shine head and Linchisalangane together form the sister group of the Zwergsalangane. To ensure that all Collocalia species are directly related and the genus would be monophyletic. The demonstrated ability of Zwergsalangane since 2004 for echolocation seems the molecular genetic findings to disagree, because this has been observed only in the Aerodramus species, which represented a major criterion for dividing the Salanganenarten to these genera. Yet this is similar to the clicking sounds used by the Zwergsalangane echolocation those of some species Aerodramus very strong. Accordingly, the echolocation in swiftlets would either have been developed several times independently or in some species, rather also have the other two Collocalia species have been lost again. Both seem not very likely.

Subspecies are not distinguished in the Zwergsalangane.