Brown swifts

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Brown swifts
Systematics
Class : Birds (aves)
Order : Sailor birds (Apodiformes)
Family : Sailors (Apodidae)
Genre : Apus
Type : Brown swifts
Scientific name
Apus niansae
( Reichenow , 1887)

The brown swift ( Apus niansae ) is a species of bird from the family of the sailors (Apodidae). It is a typical representative of the genus Apus with a very uniform brown color on the trunk. The brown swift resembles the common swift common in Central Europe and, like them, is very sociable, forms large swarms and can also be found in mixed swarms with other sailors. The population is considered stable and the species is classified as safe.

description

With a body length of 15 centimeters and a wing length between 143 and 162 millimeters, the brown swift is slightly smaller than the common swift . As with this one, the crescent-shaped wings are long compared to the slender fuselage. Compared to common swifts, the tail is shorter and the tail fork is less. Both sexes look the same.

The body is very uniformly brown in color, with the exception of the indistinct, gray-white throat spot, which can vary in size from person to person. What is striking on the underside of the wing is the contrast between the inner and outer wing: the large arm covers and the arm wings are almost straw-colored and significantly paler than the brown-colored rest of the wing. This pattern can be seen in all Apus species, but the contrast is not as clear in any species as in the brown swift.

The most frequently heard call of the brown swift is a little different from the typical call of the common swift. The call that sounds like “see-u” is shorter, sharper and more bosyllabic instead of monosyllabic. In addition, a long, more croaking “ssssiiiirrrrr” can be heard.

Spreading and migrations

The Nyanza Swift is in East Africa south of the Sahara endemic . The breeding area consists of three isolated (disjoint) areas:

  1. From the coast in central Eritrea south through Ethiopia to Addis Ababa .
  2. Further east in the coastal mountains in northern Somalia to the adjacent areas in northeast Ethiopia
  3. From the mountains in eastern Uganda , including the Kidepo Valley National Park and the area around Mount Moroto , to further east in western Kenya and the far north of Tanzania , including the Arusha National Park .

The populations in the latter area are resident birds . The birds from the area around Addis Ababa can be found there during the rainy season, from February to April and from June to September. Most of the population in northern Somalia leaves the breeding area between September and March. The winter quarters are in Kenya, Uganda and Tanzania.

The brown swift is common, sometimes very common, in its range. A large and well-known colony is located in Hells Gate National Park south of Lake Naivasha .

habitat

The habitat of the brown swift is predominantly the relatively dry mountainous region, with gorges, steep rocky slopes and crags and also the cities of the highlands being preferred. The dry climate of large parts of the habitat suggests that during the daytime foraging for food, wetter areas are sought which must be within reach. The brown swift also occurs in the lowlands.

Reproduction

The breeding season in Eritrea is between April and May, in Ethiopia between April and September and in Kenya in September. Brown swifts brooded in colonies, and nesting sites are found on buildings and in crevices in ravines and steep slopes. The nest is a flat bowl about 12 centimeters in diameter and consists of grass and feathers that are stuck together with saliva.

The clutch consists of one to three eggs with an average size of 23.5 x 15.5 millimeters. Both partners participate in the breeding business. The shortest incubation time is likely to be 19 days, after an average of another 41 days the birds fly out. As with common swifts, copulations are suspected in flight.

Systematics

The brown swift belongs to the Apus - super species , along with wall swifts and monochrome swifts .

In addition to the nominate form , a distinction is made between the subspecies Apus niansae somalicus . These are the birds that breed in northern Somalia and the neighboring areas of Ethiopia. This subspecies is paler in color than the nominate form, the throat spot is somewhat more distinct and more clearly delineated. Perhaps somalicus also slightly smaller than the nominate form. Despite the unmistakable similarity to the nominate form, somalicus is also regarded by some authors as a subspecies of the pale swift ( Apus pallidus ).

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

Individual evidence

  1. ↑ 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 226f, see literature
  2. ↑ BirdLife International: Species Factsheet - Nyanza Swift ( Apus niansae )
  3. ↑ Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 25f, see literature

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