White tailed hair

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White tailed hair
Elanus leucurus (Aguililla blanca - Gavilán maromero) (24907842044) .jpg

White-tailed hair ( Elanus leucurus )

Systematics
Order : Birds of prey (Accipitriformes)
Family : Hawk species (Accipitridae)
Subfamily : Sliding pairs (Elaninae)
Genre : Sliding pairs ( Elanus )
Type : White tailed hair
Scientific name
Elanus leucurus
( Vieillot , 1818)

The white-tailed pair ( Elanus leucurus ) is a small to medium-sized bird of prey from the genus of the glider-hairs . The species, which is widespread in large parts of the American continent, was first described scientifically in 1818 by the French naturalist Louis Pierre Vieillot .

Description and behavior

White swans reach a size of about 32 to 41 cm with a weight in the range of 294 to 350 g. The wingspan is between 94 and 102 cm. The female representatives of the species tend to be somewhat larger than the males, but otherwise show hardly any further sexual dimorphism . When gliding, white swans remind you of seagulls with their plumage and the way their wings are held - slightly V-shaped stretched across the body . When seated, however, they resemble some falcon species in terms of body shape and color . The plumage is colored white on the head and underside and turns into gray tones on the back. The hood is held in light gray. A long, with the exception of the two innermost light gray control feathers, a white tail and dark gray spots on the shoulders can be used to clearly distinguish similar species. Other characteristic features are gray-black hand wings and a black carpal spot . Legs and the base of the beak are colored yellowish, towards the tip of the beak the yellowish color changes into gray and black tones. A striking feature of adult birds is their large eyes with orange-red to red irises . They are surrounded by a black eye ring that widens to a spot towards the beak.

Young white tailed ruffles develop their youthful dress after about 40 days . This is generally darker than that of the adult birds and is mainly brown and yellow-brown. Furthermore, the young birds still lack the characteristic reddish iris, which is initially still colored brown. At the age of about one year, the young go through another complete moult , at the end of which they take on the plumage coloring of adult birds and can no longer be visually distinguished from them.

White swans tend to migrate on sometimes long walks outside of the breeding season, but apparently they do not follow any recognizable pattern. It is therefore assumed that this is not a classic bird migration . There are also reports of nomadic behavior in times of food shortages. Compared to other birds of prey, they are not very territorial, but can react aggressively to direct food competitors. At their roosts, especially in winter, white boars can be found in large groups, which in some regions can consist of up to 100 individuals. The oldest known white-tailed pair - a specimen from the American state of California - was at least six years old. The call of the birds is described as a whistling or plaintive keep - keep - keep .

White-tailed pair with a captured rodent

nutrition

During the hunt, white tailed razors glide for potential prey at an altitude of around 5 to 25 meters. Here they can - depending on the wind strength - stay in the air with fast wing beats for more than a minute in almost the same place. If the prey is spotted, the birds pounce with their wings outstretched over the body in one quick movement and grab it with their claws. After a successful hunt, the prey is first carried to a preferred hide, where it is finally consumed. More than 95% of the white swans feed on small mammals weighing between 20 and 70 g. These include home , harvest and field mice and cotton rats . The rest of the diet is mostly made up of small birds and insects.

Reproduction

Young white tailed male immediately after exiting its nest near Fort Worth , Texas

The breeding season of the species is extremely long, courting white swans have been observed from December to September, while nest-building activities can take place from January to August. The focus of egg-laying is in February and March. During courtship, the male circled the female in flight while shouting and bringing her food. The nest is set up by both birds together on a tree at a height of 6 to 15 meters and consists of sticks and twigs that are padded with grass and moss. After the nest-building has been completed, for which the birds need between one and four weeks, the female usually lays four, occasionally five and rarely three or six eggs. The exact number seems to correlate with the availability of potential prey. The eggs have a creamy white basic color with brown speckles and are incubated by the female over a period of 26 to 32 days. Meanwhile, the male stays nearby and supplies his partner with food. After the young birds hatch, the male adult bird initially continues to search for food alone and brings the prey to the nesting site, where the female feeds it to the young. Later, prey animals are simply dropped into the nest and taken in by the young birds independently. The young fledged after about 30 to 35 days, but occasionally return to the nest afterwards, where they are cared for by the adult birds. This behavior continues over a period of about one to two months. If the first brood is successful, pairs of white-tailed pairs may breed again in the same season. If this is the case, the young birds from the first brood are quickly expelled from the vicinity of the nest.

Spread and endangerment

Distribution area of ​​the Weißschwanzar

White tailed razors prefer open and semi-open areas such as grasslands, savannas , swamps and overgrown coastal dunes. Here, both dry and humid regions are settled. The animals are partly cultural followers , for which agricultural areas as well as parks and meadows tended by humans offer good living conditions. The distribution area and the population development of the species were subject to considerable fluctuations in the past. Originally the species inhabited large parts of South and Central America as well as the south and west of North America, but had disappeared from many regions at the beginning of the 20th century and was on the verge of extinction, at least in North America. The main reasons for this were above all the intensive direct hunt for birds of prey and the collection of eggs from the clutch. However, due to the restriction of hunting and, above all, the creation of new suitable habitats, the populations have since recovered. In some cases, areas have even been opened up in the last few decades in which white-tailed razors cannot be historically proven, for example in northern Mexico , where the birds presumably immigrated from California. The species particularly benefits from clearing forests and the associated creation of more open areas that can be used by their preferred prey. In general, white swans are very adaptable and, thanks to their nomadic behavior, they can react well to regionally restricted disturbances and food shortages. The species hardly has any natural predators. A Predation by Rotschwanzbussarde is considered possible, but is likely to be quite rare. Furthermore, the clutches of the species occasionally fall prey to predators such as the American crow.

Today's distribution area is very large, but patchy. It stretches from the south and west of the United States across Central and South America down to central Chile and central Argentina . Overly forested regions such as the Amazon basin and the highlands are avoided . The maximum height at which the white-tailed pair has been detected is around 1500 meters. The IUCN classifies the species as not endangered as of 2016 (status least concern ) and assumes a positive population trend for the future as well.

Systematics

Louis Pierre Vieillot described the white-tailed pair in 1818 based on a type specimen from Paraguay under the scientific name Milvus leucurus and initially placed it among the kites . During the 20th century, the species was long regarded as conspecific with the glider ( Elanus caeruleus ) widespread in Europe and Africa and was listed as its subspecies Elanus caeruleus leucurus . It was not until the early 1990s that the white-tailed pair was reassigned the status of a separate species based on serious differences in size and body shape, plumage, and hunting and flight behavior. In addition to the nominate form Elanus leucurus leucurus , the subspecies Elanus leucurus majusculus , which differs in terms of size and geographical distribution, is currently considered valid. While Elanus leucurus leucurus inhabits the South American continent, Elanus leucurus majusculus occurs in North and Central America. The border of the two distribution areas is in Panama.

  • Elanus leucurus leucurus ( Vieillot , 1818)
  • Elanus leucurus majusculus Bangs & TE Penard , 1920

literature

  • Janet M. Ruth, David J. Krueper: Raptors of New Mexico . Ed .: Jean-Luc E. Cartron. University of New Mexico Press, Albuquerque, NM 2010, ISBN 978-0-8263-4145-7 ( limited preview in Google Book Search). see chapter 5: White-tailed kite ( Elanus leucurus )

Web links

Commons : White-tailed Hair ( Elanus leucurus )  - Collection of images, videos and audio files

Individual evidence

  1. ↑ White-tailed Kite - Elanus leucurus. In: sfbaywildlife.info. Retrieved December 10, 2019 .
  2. ↑ White-tailed kite. In: allaboutbirds.org. The Cornell Lab of Ornithology, accessed December 10, 2019 .
  3. ↑ a b Kenn Kaufman: White-tailed Kite. In: audubon.org. National Audubon Society, accessed December 10, 2019 .
  4. ^ A b Troy E. Corman: The Arizona Breeding Bird Atlas . Ed .: Troy E. Corman, Cathryn Wise-Gervais. University of New Mexico Press, Albuquerque, NM 2005, ISBN 0-8263-3379-6 , pp. 122-123 .
  5. ↑ D. Randall Pinkston, Jerry G. Caravioti: Probable predation on white-tailed kite by red-tailed hawk . In: Raptor Research . tape 14 , no. 3 , 1980, p. 85-86 .
  6. ↑ James B. Dixon, Ralph E. Dixon, James E. Dixon: Natural History of the White-Tailed Kite in San Diego County, California . In: The Condor . tape 59 , no. 3 , 1957, pp. 156-165 , doi : 10.2307 / 1364721 .
  7. ↑ White-tailed kite Elanus leucurus. In: iucnredlist.org. BirdLife International, 2016, accessed December 11, 2019 .
  8. ↑ Louis Pierre Vieillot: Nouveau dictionnaire d'histoire naturelle, appliquée aux arts, à l'agriculture, à l'économie rurale et domestique, à la médecine, etc. Volume 20 . Paris 1818, p. 563 .
  9. ↑ Kenneth C. Parkes: Specific relationships in the genus Elanus . In: The Condor . tape 60 , no. 2 , 1958, p. 139-140 , doi : 10.2307 / 1365270 .
  10. ^ William S. Clark, Richard C. Banks: The taxonomic status of the White-tailed Kite . In: The Wilson Journal of Ornithology . tape 104 , no. 4 , 1992, pp. 571-579 .
  11. ^ White-tailed pair Elanus leucurus (Vieillot, 1818). In: bsc-eoc.org. Avibase, accessed December 11, 2019 .
  12. ↑ White-tailed kite (majusculus). In: bsc-eoc.org. Avibase, accessed December 11, 2019 .