Cape sailors
| Cape sailors | ||||||||||
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Cape Swift ( Apus barbatus ) |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Apus barbatus | ||||||||||
| ( Sclater , 1866) |
The Cape Swift ( Apus barbatus ) is a species of bird from the family of the sailors (Apodidae). The species is typical of the large Apus species and is very similar in shape to the pale swift and its closely related species. The Cape Swift has the darkest plumage within this relationship. The fragmented distribution area is in Africa south of the Sahara , mainly in East and South Africa , also in Madagascar . It is very common, at least in parts of its range, and is therefore classified as safe.
description
The capsuleer has a body length of 16 centimeters, the wing length is between 172 and 186 millimeters, the weight averages about 42 grams. As with the pale swift, the body is somewhat more massive compared to the common swift in Central Europe , the wings appear less pointed.
The underside of the Cape Swift is black, with the exception of the almost triangular, whitish throat patch, which can vary in size from person to person. The surrounding almost black feathers increase the contrast, but the throat spot is not always noticeable. The middle back is also almost black and has a bluish tinge.
On the underside of the wing, the plumage towards the body ( proximal ) is lighter than on the outside, especially the large arm covers and the arm wings are paler in color than the rest of the wing. However, this contrast is by far not as strong as that of the brown swift , the only similar species whose breeding area overlaps that of the Cape Swift. The Cape Swift is usually easy to distinguish from the Brown Swift, as the bright throat patch of the Cape Swift is much more clear and the plumage of the Brown Swift is brown instead of black.
Compared to the common swift , which meets the Cape Swift during the southern summer, the lighter underside of the inner wing is the best distinguishing feature besides the shape. Compared to the Common Swift, the contrast between the inner and outer wings of the Cape Swift is much clearer.
The most frequently heard call of the Cape Swift is typical of the Apus genus , but it is significantly higher than that of the Common Swift and therefore sounds more hissing.
Spreading and migrations
The range of the Cape Swift is scattered across Africa south of the Sahara , mainly in East and South Africa , and also in Madagascar . A precise documentation of the breeding area of this species is made difficult by numerous individual sightings outside the known area as well as by confusion with other species. The breeding area may be larger than previously known.
The westernmost occurrences of the Cape Swift are in Sierra Leone , in northern Liberia , in southern Nigeria , in southwest Cameroon , on Bioko , in northeastern Angola and in the central coastal section of Namibia . It is possible that it is only a question of "summering" birds, but in northern Liberia the species is considered a resident bird .
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In East Africa the Cape Swift occurs from eastern Uganda - for example on Mount Moroto - east to Kenya and as far as the far north of Tanzania . Another, isolated occurrence is in northeastern Tanzania. Further to the west there is a smaller distribution area, which extends from the east of the Democratic Republic of the Congo to the southwest of Uganda. In these three areas the species is resident.
Another, larger distribution area extends from western Mozambique and southern Malawi and extends southwest to the east and north of Zimbabwe . The birds can also be found here all year round. In contrast, the populations of South Africa leave the breeding area in the winter of the southern hemisphere. This area stretches from the Transvaal through the provinces of KwaZulu-Natal , Eastern Cape to Cape Town in the Western Cape Province . There are more isolated occurrences between these main African areas, especially in Zambia, Botswana and Zimbabwe, including near Victoria Falls . In some of these areas it is assumed that these are migratory birds originating from other areas, but in some cases there is also evidence of breeding. To the east of the African mainland, the Cape Swift still occurs in Madagascar , especially in the lowlands, and also on the Comoros .
habitat
The Cape Swift occurs mainly in the moist mountainous country, but can also be found in habitats bordering on such areas, even at lower altitudes. In some areas it occurs on the cliffs, for example near Cape Town. The breeding area is mainly in an altitude range between 1600 and 2400 meters, less often below, but occasionally also at sea level. On the Comoros the Cape Swift can be found in all habitats of the archipelago.
Behavior and food acquisition
Like the Common Swift , the Cape Swift is sociable. It can be found in swarms with hundreds of individuals, but also sporadically. It forms mixed swarms with other types of sailors. When foraging for food, it tends to hunt for insects in lower air layers than the Cape or Alpine Swift , especially in bad weather. The Cape Swift hunts above the forest canopy and also at lower altitude below large trees when the forest is lighter. Beetles , ants and termites were found to be food components.
Reproduction
The breeding season is in the East African part of the range in cold, dry periods, in the middle of the year or in the rainy season. In South Africa the laying season extends from September to February, in Malawi and Zimbabwe from August to September and in Madagascar from November to March.
The Cape Swift is a colony breeder, there are common colonies with the Alpine Swift ( Tachymarptis melba ). In East Africa the Cape Swift shows a preference for hollow trees, in particular the East African juniper ( Juniperus procera ) is preferred as a nesting site. According to recent observations, there are also tree-nesters in South Africa, but the species mainly breeds there in rock walls - if these are not made of granite . In the Cape Town area there are breeding colonies right by the sea, some are so close to the water that the breeding niches are temporarily moistened by spray.
Mostly grass is used as nesting material , but also thistle wool and feathers of our own species and other species. The nest is a flat shell, it is glued with saliva and also fixed to the ground with saliva. The lower part of the nest looks messy, at the top it looks pretty fine, but is still sturdy. The clutch consists of one or two eggs with an average size of 25.9 x 16.8 millimeters.
Existence and endangerment
The size of the distribution area is estimated at 600,000 km². Figures for the worldwide population are not available. Overall, the species is classified as harmless, but the frequency varies greatly from region to region. For example, the Cape Swift is common in South Africa, but sightings of the species in West Africa are extremely rare. There are good deposits in the Comoros and Madagascar . In the East African parts of the distribution area, the Cape Swift is far less common than in South Africa and can only be found regularly in certain areas. Since the species predominantly breeds on trees in this part of the distribution area, deforestation may have a negative effect here, especially since the birds continue to choose large trees as breeding sites if the surrounding forest, which is preferred for foraging, has been cleared.
Systematics
The African Black Swift belongs to pallidus - superspecies . In addition to him, this also includes the pale swift , the Socotra swift and the Damara swift . All species of the group are similar in shape, but differ in plumage coloring, although not clearly. The plumage of the species living in dry areas tends to be lighter than that of those found in wet areas.
Nine subspecies are distinguished, two of which - sladeniae and balstoni - are seen by some authors as separate species. Three more are questioned by some authors because of the small number of individuals examined.
- Apus barbatus barbatus ( Sclater , 1866): The nominate form colonizes South Africa and is a migratory bird. The appearance corresponds to the description above .
- Apus barbatus glanvillei Benson , 1967: This subspecies is based only on two investigated individuals from Rokupr in Sierra Leone . The representatives are a little darker in color than the nominate form, but otherwise very similar.
- Apus barbatus sladeniae ( Ogilvie-Grant , 1904): This breed is very dispersed in western Africa. It is even darker than the nominate form and also colored as glanvillei , also in the throat area; the throat patch is absent in some individuals. The enormous differences in size within this subspecies make their validity questionable.
- Apus barbatus serlei De Roo , 1970: The only sightings of this subspecies come from Bamenda in Cameroon . Their representatives are obviously darker than the nominate form, they lack the blue sheen of the dorsal plumage.
- Apus barbatus roehli Reichenow , 1906: This breed is widespread in Eastern Africa. The representatives are smaller than the nominate form and the plumage is darker. The wing length ranges from 164 to 176 millimeters.
- Apus barbatus hollidayi Benson and Irwin , 1960: This subspecies is restricted to the Victoria Falls area . The birds are paler than the nominate form, the back is colored like the wing covers.
- Apus barbatus oreobates Brooke , 1970: The representatives of this breed are similar to roehli , but a little more long-winged. It occurs in Zimbabwe and Mozambique .
- Apus barbatus balstoni ( Bartlett , 1880): This subspecies from Madagascar also resembles roehli , but is a little bit darker. The difference is most evident in the small arm covers, which are just as dark as the wings of the hand.
- Apus barbatus mayottensis ( Nicoll , 1906): The representatives of the Comoros resemble balstoni , but the plumage is a little more brownish.
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 230ff, see literature
- ↑ BirdLife International: Species Factsheet - African Black Swift ( Apus barbatus )
- ↑ a b del Hoyo et al. (1999): Handbook of the birds of the world . Page 454, see literature
- ↑ del Hoyo et al. (1999): Handbook of the birds of the world . Page 417, see literature
- ↑ Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . Page 25f, see literature
Web links
- Apus barbatus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on 6 November, 2008.
- Pictures of the capsuleer
