Eckschwanzsperber

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Eckschwanzsperber
Sounds of the corner-tailed boar? / I

Audio file / audio sample Sounds of the corner-tailed boar ? / i

Systematics
Class : Birds (aves)
Order : Birds of prey (Accipitriformes)
Family : Hawk species (Accipitridae)
Genre : Hawks and sparrowhawks ( Accipiter )
Type : Eckschwanzsperber
Scientific name
Accipiter striatus
Vieillot , 1808
Accipiter striatus 3.jpg
Eckschwanzsperber in youth dress
Young Eckschwanzsperber in flight

The Eckschwanzsperber ( Accipiter striatus ) is a small bird of prey from the family of the hawk-like (Accipitridae). Its range includes the boreal and parts of the temperate zone of North America as well as parts of Central America and the Caribbean .

The number of subspecies is controversial, seven subspecies are considered relatively undisputed. Some authors also consider the Central American white-breasted cattle ( A. chionogaster ) and the two South American forms Andes cattle ( A. ventralis ) and redshank cattle ( A. erythronemius ) as subspecies of this species. According to another opinion, they have a species status and then together with the Eckschwanzsperber they form a super species .

description

The Eckschwanzsperber is the smallest of the three North American Accipiter species. The sexual dimorphism is particularly pronounced in this species. While males have a body length of 24–27 cm, a wingspan of 53–56 cm and a weight of 87–114 g, females with a body length of 29–34 cm and a wingspan of 58–65 cm are considerably larger and weigh 150–218 g up to 100% heavier. The tail, which is 13-18 cm long, is, in contrast to that of the round-tailed cattle, relatively angular or slightly notched in the middle. The wings are relatively short and rounded. The legs and feet are yellow, long and very thin. The tarsometatarsus is laterally flattened, which is what the English name Sharp-shinned Hawk refers to. The beak is blackish towards the tip and becomes lighter towards the base. The beak corners are yellow or greenish yellow, the throat is colored light cobalt blue. The wax skin is whitish, yellowish or greenish yellow, the supraorbital olive green. The iris is yellow to orange in juvenile birds and turns darker to red with age. Birds with red irises are very likely to be at least three calendar years old.

Adult dress

Adult males are dark lead gray to bluish slate gray on top. The parting is dark lead-gray or sepia-colored, the feathers of the forehead are lined with cinnamon and the back of the head is blackish-gray. The reins are light gray, the ear covers and the rest of the head are yellowish brown to brownish gray. The throat is whitish to beige and often marked by dark shaft lines. The underside is roughly rust-colored banded on a whitish background on the chest, belly and flanks and interspersed with fine black lines. The banding can vary in strength or density, but only in rare cases does the white basic color hardly shine through. The leg fletching is also banded reddish, the under tail-coverts are white. The usually angular tail has three to five broad, dark gray bands on a medium gray background, of which the end band is the widest. The dark bands are narrower than the lighter spaces. In addition, the freshly moulted plumage often has a narrow, white end border, which, however, is soon barely visible due to wear and tear. The upper wings are dark lead-gray, with the banded wings at the base and on the inner vents being lightened whitish. The underside of the wings are pale gray with blackish banding, which becomes lighter on the inner hand wings and towards the end of the arm wings. The coverts and axillary feathers are banded rust-colored on a whitish background.

Females are very similar to males in plumage characteristics. On the upper side, however, they are overall browner to olive brown in color. The underside is usually less strongly banded than in the male.

Youth dress

Birds in their youthful dress are dark brownish on top. Head and neck are dark dashed on a whitish background, the dashed lines on the top of the head and neck are strongly condensed and the ear covers and neck are tinted cinnamon beige. The over-eye stripe is whitish and the crown feathers can be lined with reddish brown. The back, shoulders, rump , upper tail-coverts and upper wing coverts are matt dark brown-gray with yellowish or reddish beige hems. Like the rest of the top, the control springs and rockers are colored or grayer. The former have three to five dark bandages and a whitish lace hem, the latter an inconspicuous banding. In addition, the arm wings show a light to cinnamon-colored outer edge. Individual shoulder feathers and inner arm wings can have large white spots. The underside is light brown, brown or dark reddish brown, longitudinally striped on a white or cream-colored background. The drawing is strongest on the chest and becomes narrower and elongated teardrop-shaped towards the belly. Flanks and leg fletching can be banded dark. The under tail coverts are lined with white and sometimes yellowish beige. The underside of the wing is whitish with dark banding on the wings and partly teardrop-shaped longitudinal stripes or banding on the lower wing covers.

voice

The vocal expressions of the corner tail cuckoo have hardly been investigated. Overall, the species does not seem to be very happy to be called, only during the breeding season couples at the breeding site communicate a lot by means of various vocalizations. The male's voice appears to be higher than that of the female. The alarm call is an excited kek-kek-kek or kik-kik-kik . In contrast to the similar calls of the round-tailed boar, these calls are higher, quieter and faster. When hating a Great Horned Owl , a call has been identified that can be rendered ricki-ticki-ticki-ticki-ticki . A plaintive whistling is described as a presumed courtship call.

distribution

The brood distribution of the corner-tailed sparrow extends in North America over the zone of the boreal coniferous forests and, excluding central North America, in two foothills southwards: in the west along the Rocky Mountains and the Sierra Madre Occidental to Central America; to the east along the Appalachian Mountains . The species is also found in parts of the West Indies .

In the north, the area extends roughly to the Arctic tree line . It stretches across central and southeast Alaska; In Canada, the northern edge of the distribution runs through the northern Yukon and centrally through the Northwest Territories , the extreme southwest of Nunavut , the extreme northeast of Saskatchewan , the north of Manitoba and Ontario and central Quebec . In addition, the species still occurs in the south of Labrador , in the southeastern part of Newfoundland and probably on Anticosti . In southern Canada, it is absent in southeast Alberta , southwest and southern Saskatchewan with the exception of Cypress Hills and southwest Manitoba.

In the western United States, the brood distribution ranges from Washington , Idaho and western Montana south to central California , southern Nevada , northwest and southeast Arizona, and southern New Mexico . To the east, the distribution extends in foothills and islands to southeast Wyoming , to North and South Dakota , to central Colorado and to central eastern New Mexico. Possibly the species is a rare breeding bird in the mountain forests of western Texas . In the east of the United States, the area extends from northeast Minnesota through the Great Lakes area to the eastern edge of the Appalachians and scattered to the east coast and along the Appalachians southwest to and including Tennessee . However, there are also sporadic breeding occurrences in the central United States and south of the main distribution.

In Central America, the distribution extends from eastern Sonora and western Chihuahua along the Sierra Madre Occidental and through the Sierra Madre del Sur to the north of Oaxaca and in a spur at the Sierra Madre Oriental northwards to the southeast of Coahuila . There are other occurrences in northern Coahuila, in the west of Guerrero and probably in the north of Baja California Norte . Of the West Indies, Cuba , central Hispaniola and parts of Puerto Rico are populated.

hikes

The Eckschwanzsperber is a partial migrant , whose northern populations largely clear their breeding areas and move southwards in a broad front and high altitude. The populations south of the United States are predominantly resident birds .

The wintering areas lie south of a line that runs roughly from the southeastern coast of Alaska through southern British Columbia, central Idaho, Montana, South Dakota, southern Minnesota, central Wisconsin and northern Lower Michigan, through southernmost Ontario, the northern New York and the New England states to southeastern Newfoundland. They extend southward into western Panama and across the West Indies to the Bahamas . In Bermuda , the species is an occasional winter visitor.

The first migrants can be seen from the beginning of August at the observation points in the north of the USA. At Hawk Mountain Sanctuary in Pennsylvania, the majority of corner-tailed sparrows will pass through October. Maximums can be found there around October 7th and the migration process is largely over at the beginning of November. The spring migration is generally less noticeable. It begins in Pennsylvania in late March and ends in early May.

Geographic variation

Seven subspecies are recognized:

  • Accipiter striatus fringilloides Vigors , 1827 - Cuba
  • A. s. madrensis Storer , 1952 - Guerrero and possibly western Oaxaca
  • A. s. perobscurus Snyder , 1938 - Haida Gwaii and possibly the opposite coastal region in British Columbia
  • A. s. striatus Vieillot , 1808 - Hispaniola
  • A. s. suttoni Van Rossem , 1939 - extreme south of New Mexico south to Veracruz
  • A. s. velox ( Wilson, A ), 1812 - Alaska and Canada southward to California
  • A. s. venator Wetmore , 1914 - Puerto Rico

habitat

The Eckschwanzsperber breeds in almost all forest forms and especially in those that have at least a few conifers . The altitude distribution extends from the plain to high mountain regions.

nutrition

Eckschwanzsperber with prey

The Eckschwanzsperber feeds mainly on small birds. Small mammals and occasionally insects are less common prey.

Most of the captured birds are songbirds with a weight of less than 40 g, but also migrating thrushes with a body weight of around 77 g are beaten. The largest prey identified so far was a collar hen . The most frequently captured genera include Dendroica , Melospiza , Turdus , Hylocichla and Spizella and, according to another study, Junco and Passer . During the breeding season, the number of songbird nestlings captured is often very high.

The prey is usually attacked in a surprise attack from cover, from a control room or from low flight. Sometimes it comes down to a short chase. Usually, however, the hunt is quickly abandoned if an attempt to attack fails. Before being eaten, the prey is usually plucked from an elevated location.

Reproduction

Two nestlings of the corner-tailed sparrow

Most corner-tailed cows first breed when they are two years old. Some birds, most of which are females, brood in their first year of life. There is an annual brood. In Puerto Rico, if the first brood is lost, replacement broods are created. The species is believed to be monogamous , but no more detailed studies are available.

In the temperate latitudes, the corner-tailed cattle arrives in the breeding areas around the end of April. The laying time here extends over the months of May and June. The young fly out between the beginning of June and the end of September at the latest. In the tropics, where the species is stationary, the territories are reoccupied from December or January. In Puerto Rico, eggs are laid between mid-March and late April, and the young fly out between mid-May and late June. The breeding season here is extended by about two months.

During the breeding season, the area is vehemently defended against intruders. The species behaves very secretly, but is noticeable by the courtship flights above the nesting site. Both partners circle at a greater height, perform wave-like flight maneuvers or slide downwards at great speed with the wings attached. The courtship flights last between three and 20 minutes, after which the birds drop back down into the canopy. After the courtship flights, copulation often occurs.

The eyrie is mostly in trees with good cover and is a good distance below the tree tops. Typically, small groups of conifers in deciduous forest stands are chosen; the species also nests in deciduous trees or in all possible forest forms. The area around the nest site is usually moved back into the following year, although the old nest is rarely used. In some areas there were up to five old clumps.

Both partners bring in the nesting material, which is mainly used by the female. The eyrie is a wide and flat structure made of dead conifer branches , which is sometimes lined with bark. It is often relatively large compared to the size of the species. The diameter is between 35 and 60 cm, the height between 10 and 14 cm.

The clutch consists of 3–8, but mostly 4 or 5 round oval eggs of about 38 × 30 mm in size. They are spotted on an off-white or bluish white ground to varying degrees, brown, wine-reddish, violet or nut-brown, whereby the speckles can be condensed on the ground or in the middle. The surface is matt. Since the young usually hatch within 48 hours, incubation will probably only begin when the clutch is at least partially complete. The incubation period is around 30–32 days, with the male only rarely breeding.

After hatching, the young are about 16 to 23 days by the female brooded . During the incubation and the humping phase, the male completely supplies the female and later the young with prey. To do this, it looks for the surroundings of the eyrie, sits down with an already plucked prey at a slightly elevated place and calls the female to hand it over. If it then stays near the nest for a longer period, it is aggressively driven away by the female. Later on, the female also takes part in hunting down the prey. In the beginning it cuts up the food and feeds it to the young. Only in the time before the young are fledged is the prey simply placed on the nest. After the flight, both parents continue to bring in food. First they drop the prey into the nest, later it is handed over to the young in the air. After six weeks, the male drastically reduces food supplies. In the tropics, this “weaning” apparently takes place about one to two weeks later.

The cubs begin their first attempts to hunt on their own around the age of 40. In Puerto Rico, this could only be observed in young birds 51–68 days old.

literature

Individual evidence

  1. ^ AOU Checklist of North and Middle American Birds , accessed December 30, 2012
  2. ^ The Internet Bird Collection , accessed December 27, 2012
  3. ^ IOC World Bird List Version 3.2 ( Memento from December 5, 2013 in the Internet Archive ), accessed on December 27, 2012
  4. ↑ a b c Bildstein et al. (2000), section Distinguishing Characteristics , see literature
  5. ↑ Ferguson-Lees (2009), p. 182, see literature
  6. ↑ a b c Bildstein et al. (2000), section Appearance , see literature
  7. ↑ Bildstein et al. (2000), section Sounds , see literature
  8. ↑ a b c d Bildstein et al. (2000), section Distribution , see literature
  9. ↑ a b Bildstein et al. (2000), Migration section , see literature
  10. ^ IOC World Bird List New World vultures, Secretarybird, kites, hawks & eagles
  11. ↑ Nicholas Aylward Vigors: Sketches in Ornithology, & c. & c. - On some species of birds from Cuba . In: The Zoological journal . tape 3 , 1827, p. 432-448 ( online [accessed December 23, 2014]). P. 434.
  12. ^ Robert Winthrop Storer: Variation in the Resident Sharp-Shinned Hawks of Mexico . In: The Condor . tape 54 , no. 5 , 1952, pp. 283–289 (English, online [PDF; 533 kB ; accessed on April 4, 2015]). P. 288.
  13. ^ Lester Lynne Snyder: The northwest coast sharp-shinned hawk . In: Occasional papers of the Royal Ontario Museum of Zoology . No. 4 , 1938, pp. 1-6 ( online [accessed April 4, 2015]). P. 4
  14. ^ Louis Pierre Vieillot: Histoire naturelle des oiseaux de l'Amerique septontrionale, Contenant un grand nombre d'espèces décrites ou figurées pour la Première Fois . tape 1 . Chez Desray, Paris 1807 ( online [accessed April 3, 2015]). P. 42, plate 14.
  15. ^ Adriaan Joseph van Rossem: A New Race of Sharp-Shinned Hawk from Mexico . In: The Auk . tape 56 , no. 2 , 1939, pp. 127–128 (English, online [PDF; 119 kB ; accessed on April 4, 2015]). P. 127.
  16. ↑ Alexander Wilson: American Ornithology or, the Natural History of the Birds of the United States: Illustrated with Plates Engraved and Colored from Original Drawings taken from Nature . tape 5 . Bradford and Inskeep, Philadelphia 1812 ( online [accessed April 4, 2015]). P. 116, plate 45, figure 1.
  17. ^ Alexander Wetmore: A new Accipiter from Porto Rico with notes on the allied forms of Cuba and San Domingo . In: Proceedings of the Biological Society of Washington . tape 27 , 1914, pp. 119–121 ( online [accessed April 4, 2015]).
  18. ↑ Bildstein et al. (2000), Habitat section , see literature
  19. ↑ a b c Bildstein et al. (2000), Food Habits section , see literature
  20. ↑ Bildstein et al. (2000), section Demography and populations , see literature
  21. ↑ a b c Bildstein et al. (2000), Behavior section , see literature
  22. ↑ a b c d e f g Bildstein et al. (2000), section Breeding , see literature
  23. ↑ Joseph B. Platt: Sharp-shinned Hawk nesting and nest site selection in Utah , The Condor 78 (1976), pp. 102-103.

Web links

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