Soot Sailors
| Soot Sailors | ||||||||||
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Soot sailors at the Iguazú Falls |
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| Scientific name | ||||||||||
| Cypseloides senex | ||||||||||
| ( Temminck , 1826) |
The Great Dusky Swift ( Cypseloides senex , rarely Aerornis senex ) is an edge in the tropical and tropical South America occurring species from the family of sailors . The species is known for the fact that the caves used for breeding and sleeping are on rock faces and especially behind waterfalls . The birds fly through the falling water curtains to get to their nesting sites. During the day, the sociable sailors hunt for insects high above the forests .
This is a rather large, dark brown sailor who the similar domestic and in Central Europe with a body length of 18 centimeters swifts in size slightly exceeds. He is also known in German as an old man , which is due to the pale color of the head.
description
The soot- swift is an atypical representative of the genus Cypseloides , and its English name - Great Dusky Swift , "big gloomy sailor" - roughly characterizes it. The wing length is about 16 centimeters, the weight is between 60 and 98 grams - compared to a weight of about 20 to 45 grams for the other species of the genus. The plumage is predominantly dark black-brown. The underside as well as the lower back, the rump and the tail feathers are only slightly lighter. The overall impression of the head, on the other hand, is very pale, especially on the densely feathered regions of the forehead, chin and reins. The sexes are outwardly indistinguishable. In juveniles, the middle under wing coverts are slightly lighter than the other under wing coverts.
The tail is cut straight or slightly rounded. For a sailor, the body is quite strong and the wings are relatively short. The flight appears fluttering and less elegant than most other sailors, especially those of comparable size. The soot swift's call is characteristic, it consists of a " ti ti ti " followed by a muttered " tirrtschaarr ".
distribution
The soot swift occurs exclusively in South America. The majority of the distribution area is in Brazil , in the north it extends to the lowlands on the upper reaches of the Rio Madeira , a right tributary of the Amazon , extends over the states of Mato Grosso and Pará to São Paulo in southern Brazil. In addition, the soot swift can be found in eastern Paraguay and in the province of Misiones in northeast Argentina . Another isolated breeding area is most likely in Bolivia in the Noel Kempff Mercado National Park , perhaps also in other areas of the Serranía de Huanchaca .
The soot swift is considered a resident bird . Other suspicions that it could cross the Amazon as a migratory bird and be found in Colombia east of the Andes are based on a possible sighting in Iquitos, Peru . But this is not generally recognized.
habitat
The soot swift habitat includes the evergreen tropical rainforest and the humid savannahs that adjoin to the south . It can be found from the lowlands up to a height of 1000 meters. The breeding and sleeping places are apparently without exception on rocks in the immediate vicinity of waterfalls, provided that cavities have formed there. Some of these caves are located directly behind the waterfalls. They are left early in the morning and visited again in the evening. When flying through the water curtain, the sailors are occasionally carried away a good bit by the falling water. However, it seems that they are hardly harmed during these maneuvers, at least there are seldom finds of dead birds that were washed up further downstream.
During the day, the sooty swifts hunt for insects high above the forests for foraging . They are often associated with swarms of the collar swift ( Streptoprocne zonaris ).
Reproduction
The breeding season generally falls in the rainy season in areas with variable rainfall. Soot swifts breed in colonies on horizontal cliffs or caves on or behind waterfalls. The nest is a shallow bowl made of moss and small stones, held together by the use of clay and possibly saliva. The nests are sometimes exposed to direct sunlight.
The clutch usually consists of only one egg; replacement broods appear after the loss of eggs. These can become necessary if the sailors can no longer reach their nesting sites for a longer period of time due to large amounts of water after heavy rainfall. Little is otherwise known about the breeding biology of the species; due to the damp and cool breeding sites, it is assumed that the breeding and nestling times will be quite long. The dense, warming half- down plumage of the nestlings is interpreted as an adaptation to these nesting sites. When flying out, the young birds must immediately cross the water curtain of the waterfall in many places.
Existence and endangerment
Until 1994 the species was classified as Near Threatened by the IUCN ("warning list"). The soot-swift is no longer seen as endangered. Although it occurs only sparsely in the distribution area, it is quite common in some places in Brazil. However, no usable data is available for the existing population or for its development. The future of various breeding areas could be jeopardized by the construction of dams .
Systematics
The soot swift is an unusual representative of the genus Cypseloides , its size considerably exceeds all other species of the genus. For this reason it was proposed to assign the species to its own genus Aerornis . However, this point of view has not yet met with greater acceptance, and there have not yet been any molecular genetic studies of kinship relationships.
No subspecies are distinguished.
Evolution of breeding at waterfalls
In general, sailors tend to choose nesting sites that are difficult to access. In the case of the soot swift, it is also noteworthy that breeding occurs in the rainy season, i.e. the period in which the nesting sites are most difficult to reach due to large amounts of water. The sailors seem to accept this handicap because of the larger supply of insects compared to the dry season. According to Josef H. Reichholf , this is also the key to explaining the evolution of this behavior. At the time of the Pleistocene - during which the separation of the species is to be regarded as realistic due to the great differences to its closer relatives - the dry phases were much more pronounced and forced the sooty swift to breed in the rainy season. Even during the periods of high rainfall, the water curtains of the waterfalls were likely to have been thin and transparent at that time - as is currently the case with the waterfalls of Amazonian clear water rivers - and thus did not represent an obstacle for the birds. With the later increase in water masses, they were able to keep flying through the water curtain because they were used to this behavior in the meantime and any losses that might have occurred should have been compensated for by the advantage that the nesting site was now even more difficult to reach for nest robbers.
Accordingly, waterfall breeding in the soot swift cannot be explained in the same way as in the closely related Red-necked Swift ( Streptoprocne rutila ), which also breeds near waterfalls - but not behind them. In the case of the much better researched Red-necked Swift, it is assumed that breeding in such places represents a selection-neutral exploitation of the available spectrum of possible nesting places. The fact that the range of its nesting sites is much narrower than that of the Red-necked Swift speaks against the transfer of this explanation to the soot-swift. The soot swift can also hardly have been pushed away by the much smaller red-necked swift to the breeding grounds behind the waterfalls, especially since neither species occur syntopically anywhere .
With the giant salangan ( Hydrochous gigas ) native to Southeast Asia , a completely different sailor agrees better with the sooty swift in terms of breeding biology and behavior. The bird, called Waterfall Swift in English, also breeds behind waterfalls and, like the sooty swift, is atypically large compared to its close relatives. Thus the giant salangan , which is not closely related, shows convergent adaptations, which in this species could have originated in a similar way during the Pleistocene as in the soot swift.
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 .
- Josef H. Reichholf : Breeding and sleeping places behind waterfalls: Evolutionary consideration of the extraordinary behavior of the Brazilian soot swift (Cypseloides senex) . In: Ornithological Indicator. Journal of Bavarian and Baden-Württemberg ornithologists. Volume 43, Issue 1, May 2004, pp. 49-55.
- d el 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
- ↑ a b c d e f g h i j Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World. P. 113, see literature
- ↑ a b c d e f g h Reichholf (2004): Breeding and sleeping places behind waterfalls . See literature
- ^ Whitney et al .: Distributional and other noteworthy records for some Bolivian birds. Bulletin of the British Ornithologists' Club, 114, 1994, ISSN 0007-1595 , pp. 149-162.
- ↑ a b del Hoyo et al .: Handbook of the birds of the world. 1999, p. 395, see literature
- ↑ a b Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World. P. 21, see literature
- ↑ Cypseloides senex in the Red List of Threatened Species of the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on 12 November, 2008.
Web links
- Cypseloides senex onthe IUCN Red List of Threatened Species .
- www.mangoverde.com: Great Dusky Swift (pictures)
