Black swifts

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Black swifts
Adult black swift sitting in nest in Shoshone County, Idaho

Adult black swift sitting in nest in Shoshone County , Idaho

Systematics
Class : Birds (aves)
Order : Sailor birds (Apodiformes)
Family : Sailors (Apodidae)
Genre : Cypseloides
Type : Black swifts
Scientific name
Cypseloides niger
( Gmelin , 1789)

The black swift ( Cypseloides niger ) is a species of bird from the family of the sailors (Apodidae). With a body length of about 18 centimeters, the black sailor belongs to the medium-sized sailors. The plumage is predominantly dark black-brown - except in the area of ​​the head, where the coloring, especially on the forehead, is gray and noticeably paler.

The species is a medium to long-distance migrant . The breeding area extends over the west of North America, Central America and the West Indies , the winter quarters are in the north and west of South America. The black swift can only be found regularly in a very few, narrowly defined parts of the distribution area; the frequency varies significantly from region to region. The nesting sites are on steep rock faces or in caves, typically in the immediate vicinity of waterfalls. In the entire breeding area there is only one annual brood, the clutch consists of only one egg.

A distinction is made between three subspecies , the breeding form in North America being significantly larger than the two Central American subspecies. The worldwide population is roughly estimated at 150,000 adult birds, the breeding area at almost 1.3 million square kilometers.

features

The body length is approximately 18 centimeters. The North American subspecies ( C. n. Borealis ) is significantly larger than the representatives of the species that breed in Central America. In studies of North American black swifts, the average wing lengths measured were around 169 millimeters, and the average weight was 46 grams. Measurements in Costa Rica , on the other hand, showed an average of 160 millimeters for the wing length and around 35 grams for the weight.

Appearance

The fletching of the top of the head is dark gray and clearly shows pale, light gray feather edges. The throat and ear covers are sooty, gray-brown in color, and the chin is lighter. The light color of the head contrasts with a dark eye spot. The upper side behind the nape is black-brown, the rump and upper tail-coverts appear a little lighter. The color of the sooty-gray-brown throat extends into the middle of the chest, below which the plumage is black-brown. Indistinct, gray-brown feather edges can be seen on the underside, especially with freshly molted plumage. The flight feathers are lighter on the bottom than on the top. The large arm covers on the underside of the wings are colored similarly to the wing feathers, while the medium and small arm covers are darker and correspond to the color of the trunk. The tail color and the color of the wing feathers correspond on the top and bottom. The tail is slightly forked, it also shows an indistinct tendency to tail spines; the end of the spring shaft is only slightly stiff and hardly protrudes beyond the tail end.

Both sexes look the same. Young birds differ from adult birds in that the head plumage, the wing feathers and especially the plumage on the underside show clear white feather fringes. This creates a noticeable, speckled pattern below the lighter area of ​​the throat.

Vocalizations

The vocalizations of the black swift have not yet been specifically investigated. The species is generally considered to be comparatively unrepentant. Low, equally high chirping sounds can be heard in flight, often in rapid succession that slows down towards the end. The pitch is lower than that of the chimney sail . There is also a report of a soft-sounding "Cheep Cheep" or clicks during flight games.

Spreading and migrations

Distribution of the black swift: light green = breeding area, red = resident bird

The distribution area extends over the Nearctic and Neotropical . The breeding area in North America extends in the north to the Stikine River in southeast Alaska . From there, it extends south across western Canada, where the species breeds in the northwest and central British Columbia and southwest Alberta . On the Canadian Pacific coast, the black swift occurs on Vancouver Island , but not on Haida Gwaii . In the United States, there are deposits in the states of Washington , Idaho , Montana , California , Utah , Colorado , Arizona, and New Mexico . In Mexico, the species occurs on the Pacific slope from the west of Chihuahua to Oaxaca , and also further east of Hidalgo to the north of Oaxaca.

The deposits in Central America are even more fragmented than in North America. The distribution area extends from Chiapas in the southern Mexican interior through Guatemala , Honduras and Nicaragua to Costa Rica , in El Salvador there is no evidence during the summer. The breeding area also includes the West Indies , where the species occurs on Cuba , Jamaica , Hispaniola , Puerto Rico , St. Kitts , Guadeloupe , Dominica , Martinique , St. Lucia , Montserrat and St. Vincent . On Saint Croix , Grenada and Barbados , the species is considered an errant . There are very few breeding records within the range. However, since the breeding grounds are quite hidden, it can be assumed that the species breeds wherever it can be found in the northern hemisphere in summer.

The black swift is mainly considered to be a medium to long-distance migrant . In the Greater Antilles , the species is most likely also a resident bird . The winter quarters of the migrating birds are in the north and west of South America. In Cauca in the south of Colombia, migrating black swifts of the North American subspecies C. n. Borealis have been spotted; it is assumed that the species also over summer further south. Reliable sightings suggest that the black swifts from southern Mexico to Colombia take at least some of the shorter, more direct routes across the Pacific and not along the Central American coast. In southern California, migration begins in late August, and most birds leave the breeding area in September. In spring, the first record of a black swift returning home in California is dated April 20th, and the majority of the birds return to the breeding area in May. In other parts of the North American range, migration times are similar.

habitat

Typical breeding habitat at Burney Falls in McArthur-Burney Falls Memorial State Park in California. The birds nest in cavities and crevices behind the waterfall.

In western North America there are two characteristic habitats that offer nesting opportunities for the black swift: on the one hand, these are surf caves and cliffs along the Pacific coast, on the other hand, narrow, rocky mountain gorges with waterfalls or dripping water. The following criteria were determined according to which researchers can assess the suitability of potential habitats when looking for nesting sites inland:

  • flowing surface water that does not dry up even in the summer months,
  • the exposure of the site,
  • the possibility of free approach,
  • the shadowing,
  • the presence of suitable niches and cavities,
  • the availability of moss as nesting material.

An essential aspect of this nesting site preference is certainly the inaccessibility for ground-based predators . The preference for waterfalls could also be motivated by the constant temperature that this causes, and the moisture makes it easier to attach the nest to the ground. Far fewer nesting sites are known in the Central American breeding area than in North America. The southernmost known nesting sites are in Costa Rica on the upper reaches of the Río Tiribí at an altitude of just over 2000 meters. The altitude range of the breeding area depends on the latitude, in British Columbia it ranges from sea level to 2600 meters, in the southern Rocky Mountains from 2000 to 3550 meters, in Oaxaca in Mexico from 2100 to 3700 meters.

No well-founded statements can be made about suitable foraging habitats because the black swift's food acquisition has not yet been specifically investigated. It is believed that in warm, clear weather, the species forages at high altitudes above the ground, where large swarms of insects reside. The birds can often be found over peaks and mountain ridges. In bad weather and during the move, the sailors seem to hunt at lower altitudes, often over lakes or other bodies of water. Black swifts nesting in the mountains cover long distances in some parts of the range in order to search for food above the lowlands.

Behavior and food acquisition

The black swifts are gregarious, in California and British Columbia flocks of a thousand or more individuals have been observed during the breeding season and migration. Particularly when large swarms of insects are available, the black swift hunts for food together with collared , red-necked , breast-spot , white-chin and diademed swifts .

food

During the breeding season, swarming ants make up a large part of the prey, various studies have shown a proportion between 72 and 98 percent, the average size of the prey animals was 7.2 in one case and 8.6 millimeters in the other. Even termites are the preferred food, especially in adverse weather conditions and lack of availability of the preferred prey of the percentage increases of other flying insects. The high fat content of swarming ants is most likely directly related to the comparatively large weight of the nestlings at the time of flight. The high dependence of the black swift on short-term available large flocks probably explains some unusual aspects of the species' breeding biology - for example the often long feeding intervals and the relatively long nestling period.

Reproduction

In the entire distribution area there is only one annual brood and the clutch consists of only one egg. It is controversial whether there are replacement broods in some cases when the clutch is lost. The breeding season shows little dependency on latitude and altitude and lasts surprisingly uniformly in the entire distribution area from June to September, in southern California and Costa Rica there have been observations that indicate a breeding season begins as early as May. While the breeding season of the black swift in tropical Central America falls into the rainy season, which is typical for the genus Cypseloides , it is in the dry season in parts of the North American range - such as in southern California.

The nest is built on narrow ledges on rock or cave walls, almost always near the water. The nests built in surf caves on the Pacific coast use mostly clay and occasionally seaweed as nesting material. Mosses are the typical nesting material for nests in the interior of the country . Saliva is not used - unlike many other types of sailor. The shape of the nests depends on the subsurface: it corresponds to a half-shell or a cone pointing downwards if the nest is attached to a rock nose. On the other hand, in a niche that provides sufficient space, the nest is shell-shaped. The diameter of the nest was fairly uniformly nine centimeters in 12 nests examined in southern California, in three nests found in Costa Rica it was about six centimeters. It has often been observed that black swifts use old nests again. In many cases it could be proven that the recycler was a nest owner from the previous year, which suggests a high level of loyalty to the nesting site, which could be due to the lack of suitable nesting sites.

It takes 10 to 14 days between the completion of the nest and the laying of the egg. There is no gender-specific difference in the handling of the hatchery tasks. The dimensions of the matt white eggs are approximately 28.5 × 18.5 millimeters, the weight on average around 5.5 grams; so they are quite heavy in relation to the weight of adult birds. The breeding period in North America is an average of 24 days, in Costa Rica it is 29 days. The nestling time does not differ in North and Central America, it is between 48 and 50 days. The nestlings of the black swift build up fat reserves to an unusually large extent even for the genus Cypseloides and are at times significantly heavier than the adult birds, the North American nestlings can reach up to 146 percent of the weight of adult birds. The feeding intervals are relatively long: At the beginning of the breeding season, the nestlings are usually fed twice a day, towards the end usually only once in the evening. This extension of the feeding intervals at the end of the nestling period probably enables the adult birds to build up their fat reserves again, especially since the black swifts migrate to the winter quarters immediately after the young birds have fled - in contrast to some other migrating species of sailor.

There are only a few statements about breeding success. In southern California, young birds hatched from 81 percent of the eggs laid. The trip rates in southern California were 90 percent, in Colorado 78 percent in one year and 100 percent in the following year. The survival rate of the juveniles is unknown.

Parasites, Enemies, and Life Expectancy

Little information is there to ectoparasites : There are two family Eustathiidae belonging feather mites detected species, and two types of spring Lingen to the family Menoponidae count. The louse fly Myiophthiria fimbriata was found in one adult bird, and a nestling in Costa Rica was infested with five larvae of the fly genus Philornis .

Predators do not seem to matter, the only known one is the peregrine falcon . Simulations suggest that the survival rate of the adult birds is more important for the population development than the breeding success and the survival rate of the young birds.

There is little data on life expectancy, but it suggests that black swifts get quite old; the highest documented age to date was 16 years.

Inventory and inventory development

The worldwide population is roughly estimated at 150,000 adult birds, the breeding area at almost 1.3 million square kilometers. Estimates from the past 40 years, in which only a fraction of the North American range were recorded, show a slight population decline, but this is not statistically significant .

The decisive stock-regulating factor seems to be the availability of watercourses, which do not dry up even in the dry summer months. On the one hand, this is due to the preference for nesting sites; on the other hand, it influences the availability of the insect swarms on which the species is dependent. Forestry and livestock farming can therefore have negative effects on stocks, as they affect the water balance.

Systematics

In large parts of its range, the black swift is the only representative of the genus Cypseloides . Since it is not a typical representative of the genus, the black swift was previously placed in its own genus Nephoecetes , and sometimes the pectoral swift ( C. lemosi ) was also assigned to this genus. Molecular genetic studies did not confirm this demarcation, because this black sailors Brustfleck-, today Rothschild and smoke sailors as niger - superspecies summarized.

Gmelin's first description of the species in 1789 was based on a publication by Mathurin-Jacques Brisson , who named a bird discovered on the West Indian island of Hispaniola in 1760 as "Le Martinet de S. Domingue". Caleb Burwell Rowan Kennerly was the first to describe the North American subspecies. While working as a doctor and naturalist for the Northwest Boundary Survey , he observed a large flock of sailors on the coast of Puget Sound in Washington state in 1857 . He was able to examine a specimen of this sailor and thought it was a new species. Kennerly sent this bird to Spencer Fullerton Baird . Baird found this sailor so different in comparison to the family members known at the time that he introduced the new generic name Nephocaetes for him , from which the generic name Nephoecetes , which is still occasionally used today, was derived. Baird also recognized the similarity to the species described by Gmelin almost 70 years earlier, but initially did not consider it to be con-specific due to the size difference and the spatial distance . Even Philip Sclater , in 1895 the black sailors still valid genus Cypsloides zuordnete, considered it possible that it could be at the North American and West Indian form of two different kinds. In the first checklist published by the American Ornithologists' Union in 1886, which was considered authoritative for North American bird species in the following years, both forms were combined as Cypseloides niger .

Today three subspecies are distinguished:

  • C. n. Borealis ( Kennerly , 1858 ): The representatives of this subspecies occurring in the entire North American distribution area are significantly larger than their southern breeding conspecifics. The above description is primarily based on this subspecies.
  • C. n. Niger ( Gmelin , 1789 ): The nominate form occurs on the islands of the Caribbean, it is significantly smaller than the North American form. In the young birds of the nominate form, the white feather fringes are far less pronounced than in the young birds of the other subspecies, they can also be completely absent. The darkness of the plumage is not uniform within the nominate form; in the past, another subspecies was distinguished for the representatives south of the Greater Antilles with C. n. Jamaicensis .
  • C. n. Costaricensis Ridgway , 1910 : The representatives in Mexico and on the Central American mainland belong to this subspecies, they are somewhat larger than the nominate form, but smaller than the North American representatives. Compared to the latter, they are also significantly darker in color.

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 .
  • MA Marín, FG Stiles: On the biology of five species of swifts (Apodidae, Cypseloidinae) in Costa Rica. In: Proceedings of the Western Foundation of Vertebrate Zoology. 5, Los Angeles 1992, pp. 286-351.
  • Joseph del Hoyo, Andrew Elliot, Jordi Sargatal (Eds.): Handbook of the Birds of the World. Volume 5: Barn-owls to Hummingbirds. Lynx Edicions, 1999, ISBN 84-87334-25-3 .
  • David A. Wiggins: Black Swift (Cypseloides niger): A Technical Conservation Assessment. USDA Forest Service, Rocky Mountain Region, 2004. (online) (PDF; 1.7 MB)
  • Rich Levad: The Coolest Bird. A Natural History of the Black Swift and Those Who Have Pursued It. American Birding Association, 2010. (online) (PDF; 3.7 MB)

Individual evidence

  1. ↑ a b Manuel Marín: Growth rates in the Black Swift: temperate versus tropical comparisons. In: Ornitologia Neotropical. 10, 1999, pp. 179-192. (online) (PDF; 208 kB)
  2. ↑ a b c d e f g h i j Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World . 2000, p. 104ff.
  3. ↑ Marín, Stiles: On the biology of five species of swifts (Apodidae, Cypseloidinae) in Costa Rica. 1992, p. 297ff.
  4. ↑ a b Lowther, Collins: Black Swift (Cypseloides niger). Sounds.
  5. ↑ Sound recording of the black swift (MP3; 421 kB) by Todd Mark, Parque Nacional Basaseachi, Chihuahua, Mexico, July 20, 2006.
  6. ↑ a b Lowther, Collins: Black Swift (Cypseloides niger). Distribution.
  7. ↑ a b Lowther, Collins: Black Swift (Cypseloides niger). Breeding.
  8. ↑ a b c d David A. Wiggins: Black Swift (Cypseloides niger): A Technical Conservation Assessment. 2004, p. 16f.
  9. ↑ a b c Levad et al .: Distribution, Abundance, And Nest-Site Characteristics Of Black Swift In The Southern Rocky Mountains Of Colorado And New Mexico. In: The Wilson Journal of Ornithology. 120, 2008, pp. 331-338. (online) (PDF; 740 kB)
  10. ↑ a b Manuel Marín, Julio E. Sánchez: Breeding of the Black Swift (Cypseloides niger) in Costa Rica. In: Ornitologia Neotropical. 9, The Neotropical Ornithological Society 1998, pp. 219-221. (online) (PDF; 228 kB)
  11. ^ Lowther, Collins: Black Swift (Cypseloides niger). Habitat. 2002.
  12. ↑ a b c d Manuel Marín: Some aspects of the breeding biology of the Black Swift. In: Wilson Bulletin. 109, 1997, pp. 290-306. (Summary)
  13. ↑ a b c d David A. Wiggins: Black Swift (Cypseloides niger): A Technical Conservation Assessment. 2004, p. 17ff.
  14. ↑ a b Manuel Marín: Food, foraging, and timing of breeding of the Black Swift in California. In: Wilson Bulletin. 111, 1999, pp. 30-37. (online) (PDF; 578 kB)
  15. ^ Lowther, Collins: Black Swift (Cypseloides niger). Demography. 2002.
  16. ^ A b David A. Wiggins: Black Swift (Cypseloides niger): A Technical Conservation Assessment. 2004, pp. 19-23.
  17. ↑ BirdLife International: Species Factsheet - American Black Swift ( Cypseloides niger ) . Retrieved November 20, 2011.
  18. ↑ Marín, Stiles: On the biology of five species of swifts (Apodidae, Cypseloidinae) in Costa Rica. 1992, p. 344.
  19. ↑ Chantler, Driessens: A Guide to the Swifts and Tree Swifts of the World. 2000, p. 21.
  20. ↑ R. Levad: The Coolest Bird. 2010, p. 7f.
  21. ↑ a b R. Levad: The Coolest Bird. 2010, p. 11f.
  22. ↑ PL Sclater: Notes on the genera and species of Cypselidae. In: Proceedings of the Zoological Society of London. London 1865, p. 615. (online)

Web links

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