Horus sailor
| Horus sailor | ||||||||||
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Horus swift in South Luangwa National Park in Zambia |
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| Apus horus | ||||||||||
| ( Heuglin , 1869) |
The Horus swift ( Apus horus ) is a species of bird from the sailor family (Apodidae). The distribution area is limited to Africa south of the Sahara . Compared to the related common swift common in Central Europe , the animals appear powerful, the flight is less elegant. Caves are used as nesting sites, which have been dug in sandy walls by other bird species - especially bee-eaters . The Horus swift is common at least in parts of its range and is classified as harmless.
Horus , whom the name of the species recalls, was a god of early Egyptian mythology .
features
With a body length of just under 15 centimeters, the Horus sailor is one of the small Apus species. The wing length is between 143 and 161 millimeters, the weight averages 26 grams. The shape is quite strong compared to the related sailors and resembles that of the house sailor . The large, light throat patch and especially the white rump form a clear contrast to the otherwise dark gray-brown to black plumage. The throat patch is less clear when the plumage is removed. As with the house sailor, the light color of the rump continues a little on the rear flanks, so that it can be seen from almost every perspective. The tail has a medium length for Apus species and the tail fork with a length of the incision between 9 and 13 millimeters is also in the middle area. Both sexes look the same.
Like the house sailor, the Horus sailor flies very whirring and lacks the graceful, powerful and swallow-like flight of the related species. For this reason, and because of the white rump, the Horus swift can most likely be confused with the house swift, which occurs sympatricly in the entire range of the Horus swift . The best distinguishing feature is the tail, which in the Horus sailor is a little longer and, in contrast to the house sailor, clearly forked. The second, occurring sympatric weißbürzelige sailors is the white-rumped swift ; the more streamlined shape and the much more clearly forked tail are the best features to distinguish Cape Swift from Horus swifts.
The reputation of the Horus sailor is deeper than that of the Cape and house sailors. It sounds like "priiiuuu priiiuuu" mumbling. During the breeding season, the Horus swift calls more often than these similar species, but outside of the breeding season it is mostly mute.
Spreading and migrations
The Horus swift is native to sub-Saharan Africa, predominantly in East and South Africa. There are dispersed populations further west. Identification problems make it difficult to fully record the distribution; apart from the contiguous distribution area, the breeding sites are often difficult to access. The species may therefore be more widespread than previously thought.
The Horus swift occurs in the mountains of Ethiopia and from the middle of Kenya to the Tanzanian border in the south; however, these occurrences do not form a coherent population because the species is absent in northern Kenya. The species is also found in northwest Uganda , the neighboring areas of Burundi and the Democratic Republic of the Congo . The largest contiguous area is in southern Africa. The species is found there in southern Zambia , in Zimbabwe , in northern Botswana , in central Mozambique and in South Africa - mainly from the Transvaal in the north to Port Elizabeth in the south, but also in a narrow strip from the Western Cape along the south coast, where in The De Hoop Nature Reserve was settled in the 1990s . In addition to these larger contiguous areas, the Horus swift was found in Cameroon , Nigeria , Niger and Chad . There are also small, isolated populations in Sudan , in the west near Darfur and in the east near Sannar and Wad Madani . Other small occurrences exist on the west coast of southern Africa, in the west of the Congo and Angola . There have been possible sightings of migratory birds in the Agalega Islands and the Seychelles .
The Horus sailor is a resident bird in large areas of the distribution area . Mainly in the South African highveld it can only be found during the breeding season, the same applies to the highveld in Zimbabwe. The species breeds there between October and May. It is possible that the birds in the latter area only migrate to the Lowveld , where the species also occurs as a resident bird and breeds throughout the year. According to reports, the Horus swift can be found as a guest bird in the Zambezi Valley during the dry season. In the East African part of the distribution area the species mainly shows dismigration behavior .
habitat
The habitat of the Horus sailor is linked to that of its cave suppliers. Therefore, the Horus sailor can often be found near sandy areas, which can be natural or man-made. In Kenya the species breeds at an altitude between 1600 and 2000 meters, in Natal between 1500 and 2400 meters. Larger settlement areas are avoided when looking for food.
Behavior and food acquisition
Horus swifts are usually gregarious but do not form large swarms; a maximum of 30 individuals were counted together. They often form swarms with other sailors or swallows. In search of food, the Horus swift normally flies at a medium altitude between 20 and 30 meters, i.e. above the palm swift but below the Cape swift . Occasionally, the Horus swift hunts in the higher airspace when this altitude zone is not occupied by other species. Insects are preyed on in flight , and swarming termites , flies , beetles and swarming ants have been identified as food .
Reproduction
In the Cape Province, the Horus swift breeds from November to December and from March to April, in the Transvaal from January to March. In Zimbabwe, breeding birds can be seen year-round, with a focus on November through March. The laying time in Ethiopia is in June, in Malawi from April to May, in Zambia in the months of August and September. The Horus swift is not a real colony breeder, but just like isolated breeding sites there are often community broods of up to 12 breeding pairs, occasionally larger breeding colonies also occur. The nesting places of the Horus swifts are often scattered in a breeding colony of bee-eaters or sand martins . Community breeding is therefore also seen as a consequence of the takeover of the nests of colony-breeding species.
The abandoned nests of burrowing bird species, typically located on river banks, are taken over for breeding, especially the bee-eater, kingfishers , ground woodpeckers ( Geocolaptes olivaceus ), ternary terns ( Riparia cincta ) and possibly also the termite treacher ( Myrmecocichla formicivora ). A violent takeover of the caves has not yet been observed. The nest is at the end of the cave and consists of a flat bowl with a diameter of 10 to 14 centimeters. The nesting material used is primarily grass, dunes, maize leaves and moss, i.e. mainly vegetable material, and this is consolidated with saliva, hair and feathers. The copulations take place in the nest. The clutch consists of one to four eggs that measure an average of 25.9 x 16.8 millimeters. The incubation period is on average 28 days, the nestling period is 6 weeks.
Existence and endangerment
The Horus swift occurs regularly in large parts of the range, in parts it is even very common, for example in the Ethiopian highlands . In a Kenyan colony near Nakuru , the population was estimated to be several hundred breeding pairs.
The size of the distribution area is estimated at 1,200,000 km². Figures for the worldwide population are not available. There are signs of an increase in the population, which is why the species is classified as safe.
Systematics
With A. h. fuscobrunneus is a subspecies that is restricted to the southwest of Angola . It differs from the nominate form by a smaller, gray throat spot and by the lack of the white rump, which is instead colored gray-brown, otherwise A. h. fuscobrunneus generally paler in color.
A color morph is also distinguished, which is called Toulsoni . Birds of this morph, like A. h. fuscobrunneus have a smaller throat spot and a brown rump, but are overall darker than this subspecies. This form is found in northwestern Angola and in Zimbabwe.
Some authors see these two dark forms as Para species within a horus - superspecies . When classifying this species into subspecies, however, it should be remembered that the plumage of the Horus swift often shows heavy wear and tear due to the use of dug caves and the plumage of individual birds can therefore show very strong differences in tint.
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
- 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
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 244ff, see literature
- ↑ del Hoyo et al. (1999): Handbook of the birds of the world . Page 456f, see literature
- ↑ BirdLife International: Species Factsheet - Horus Swift ( Apus horus )
Web links
- Apus horus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 15 of 2009.
