Snake consecration

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Snake consecration
Crested Serpent Eagle - Spilornis cheela.jpg

Serpent harrier ( Spilornis cheela )

Systematics
Order : Birds of prey (Accipitriformes)
Family : Hawk species (Accipitridae)
Subfamily : Schlangenadler (Circaetinae)
Genre : Serpent harriers ( Spilornis )
Type : Snake consecration
Scientific name
Spilornis cheela
( Latham , 1790)
Aerial image of the serpent harrier
In this bird, the neck plumage that has been extended to form the “hood” is clearly visible. The nominate form Sp. Ch. cheela is the largest subspecies and is quite dark in color.
Snake consecration in youth dress
Young serpent harrier with the hood up

The snake harrier ( Spilornis cheela ) is a bird of prey from the subfamily of the snake eagle (Circaetinae). It is distributed over large parts of the Indomalay region and is one of the relatively common species of birds of prey there.

The geographic variation is particularly pronounced in the Malay Archipelago . Of the numerous island forms, many are also regarded by some authors as separate species.

description

The snake harrier varies geographically with 43–74 cm body length and a wingspan of 95 to 169 cm in size. The nominate form is the largest and reaches a little more than the size of a short-toed eagle , while the smallest form is about the size of a common buzzard . The weight is between 420 and 1800 g, but is not well documented. Males and females hardly differ. However, females are about 4–6% larger and probably significantly heavier than males.

In flight, the medium-sized to large bird of prey appears large-headed with a relatively long tail, which is usually kept closed, and rounded wing tips. It flies with powerful wing beats and short gliding phases, in which the wings are held at or slightly above the level of the body axis. In soaring flight they are held in a flat V.

In adult birds, the crown and nape of the neck are black. The latter is extended to a hood that can be opened and lined with beige or white spots. The iris is yellow as are reins and wax skin . The rest of the top is dark brown, from which a fine, white drawing of openwork end hems on the shoulders, arm covers and rump stands out. The chin, throat and sides of the head vary between black, grayish or brown. The light brown breast can be densely banded with dark, finely scribbled or almost undrawn. The belly, leg fletching and lower tail are more reddish-brown with fine dark banding or a black-lined, white spot that varies greatly in size, shape and conspicuity. The feet and legs are colored matt yellow. Especially in flight, a wide white wing band on the otherwise blackish wings is noticeable underneath, which is formed by the whitish bases of the arm wings and a central band on the hand wings; two narrower white bands often run at the bases of the wings of the hand. A gray-white band runs across the middle of the blackish control springs , the width of which corresponds to the wing band. Both features make the flight pattern very distinctive.

In youth clothing, the crown, sides of the head and hood are yellowish beige to whitish with a black scale pattern. The black ear covers form a striking, dark field. In addition, the bird is dark brown to blackish or reddish brown on top with very variable whitish spots, stripes or fringing. The dark brown control feathers show a whitish end band and two further, wide light bands. They are mottled brown on the top, greyish on the underside. The beige-white underside is sparsely drawn with dark brown drops or dashes. The lower flanks, leg fletching and lower tail are often banded with rust brown.

voice

The species can be heard loudly during the expressive flights before and during the breeding season, but it is also otherwise very loud. The typical call, a piercing pi-pi-wieeh-wieeh , is one of the most frequently heard, conspicuous and catchy raptor sounds of the Orientalis. The introductory two to three sounds are a little quieter than the one, two or more rarely three-syllable scream that follows.

distribution

The distribution area of ​​the serpent harrier extends over the majority of the Orientalis and protrudes a little into the Palearctic in the northeast and northwest . In the Malay Archipelago , the definition of the distribution area is heavily dependent on which island forms are counted as subspecies of this species or which species status is granted.

From individual occurrences in Sindh and Khyber Pakhtunkhwa in Pakistan, the area extends eastward across the Indian subcontinent including Sri Lanka . In the northwest, the Himalaya limits the occurrence. The northern border runs through Kashmir , Nepal , Bhutan and Assam , in China through Yunnan , Guizhou , Hunan and along the lower reaches of the Yangtze River . In East Asia the distribution includes Hainan , Taiwan, and the Ryūkyū Islands . To the south, the area extends over the Andamans , the Nicobar Islands and India . Of the Great Sunda Islands , Sumatra (including the Batu Islands , Mentawai Islands , Simeuluë , Nias and Bangka ), Java with Madura and Borneo are populated. In the Philippines , the species occurs only on Palawan , Balabac and the Calamian Islands . The Anambas Islands , the Natuna Islands , Bawean , Belitung and Bali also belong to the brood distribution.

hikes

The snake harrier is generally a resident bird . Only locally seasonal migrations or migration from higher altitudes were found. Immature birds are prone to dispersions

Geographic variation

The variation and systematics within the genus Spilornis with its numerous island shapes is very complex and highly controversial. There are twenty-seven taxa in all. While many authors only recognize three or five of the island's populations as their own species, others have up to thirteen. The International Ornithological Committee assigns twenty subspecies to this species, while one form from the Andamans ( elgini ), two from the Nicobar Islands ( minimus and klossi ), one from northern Borneo ( kinabaluensis ), the populations of the Philippines ( holospilus ) and Celebes ( rufipectus and sulaensis ) can each be seen as separate species.

The populations sometimes vary greatly in size, so that the smallest forms are three fifths smaller and sometimes more than half lighter than the largest. Another varying characteristic is the coloring of the upper side of adult birds, which ranges from black-brown to reddish brown to pale brown in the various forms. The underside ranges from blackish brown or maroon to yellowish beige. The drawing on the underside is also sometimes very different and ranges from strong spots or bands to a barely visible drawing.

  • Sp. Ch. cheela ( Latham , 1790) - Northern India and Nepal
  • Sp. Ch. melanotis ( Jerdon , 1844) - India south of Gujarat and the Ganges plain
  • Sp. Ch. spilogaster ( Blyth , 1852) - Sri Lanka
  • Sp. Ch. burmanicus Swann , 1920 - Myanmar , southwestern China, Thailand and the Indochinese Peninsula
  • Sp. Ch. davisoni Hume , 1873 - Andaman and possibly Nicobar
  • Sp. Ch. ricketti Sclater, WL 1919 - Northern Vietnam and Southern Central and Southeast China
  • Sp. Ch. perplexus Swann 1922 - southern Ryūkyū Islands
  • Sp. Ch. hoya Swinhoe , 1866 - Taiwan
  • Sp. Ch. rutherfordi Swinhoe , 1870-Hainan
  • Sp. Ch. palawanensis Sclater, WL , 1919 - Palawan
  • Sp. Ch. pallidus Walden , 1872 - Lowlands in northern Borneo
  • Sp. Ch. richmondi Swann 1922 - southern Borneo
  • Sp. Ch. natunensis Chasen , 1935 - Natuna Islands and Belitung
  • Sp. Ch. malayensis Swann , 1920 - Malay Peninsula from southern Tenasserim southwards as well as Anambas Islands and northern Sumatra
  • Sp. Ch. batu Meyer de Schauensee & Ripley , 1940 - southern Sumatra and Batu Islands
  • Sp. Ch. abbotti Richmond , 1903 - Simeuluë
  • Sp. Ch. asturinus Meyer, AB , 1884 - Nias
  • Sp. Ch. sipora Chasen & Kloss , 1926 - Mentawai Islands
  • Sp. Ch. bido ( Horsfield , 1821) - Java and Bali
  • Sp. Ch. baweanus Oberholser , 1917 - Bawean

habitat

The snake harrier occurs in a wide range of forest forms, including both deciduous and evergreen forests, wet and dry, closed or semi-open habitats, as well as plains and mountain forests. It occurs in both primary and secondary forests or forests and plantations. The species can also be found in wooded savannahs , wooded gorges or gallery forests. At least on the Andaman Islands, it also occurs in mangroves . The species also hunts near settlements and in cultivated land. The height distribution extends to sometimes over 3000 m.

nutrition

The food of the serpent harrier consists mainly of reptiles , with snakes making up the largest proportion and a smaller percentage of lizards being captured. Occasionally there are frogs and small mammals, and more rarely sick or injured birds. Crabs and an eel have also been found prey in the Andaman Islands.

The prey animals are usually captured from a hide, which is often located on the edge of a clearing and on which the bird sometimes sits motionless for a long time before it descends to attack. The antlers may also lie in wait for tree-dwelling snakes or lizards within the canopy. Air hunting does not occur in this species.

Reproduction

The breeding season of the consecration varies depending on the geographic location and altitude above sea level. In the north of the range, the egg-laying time falls in the dry season. In the hill country of northern India it is between March and July, in the lowlands between February and May. In the south of India it begins as early as December, in Myanmar there are first clutches from February. On Java, clutches are found in most months of the year, but mostly between February and November.

The relatively small nest with a diameter of 50–60 cm and a height of 10–30 cm consists of twigs and is lined with green leaves. It usually stands at a height of 6–20 m or more in a central fork of a branch. Nests are often found near water and can be found in forests as well as in smaller trees in the semi-open landscape. The clutch consists of one, and sometimes two eggs and is incubated for around 35 days. The young fly out after about 60 days.

  • Nest with an egg in East Java (1934)

  • Feeding adult bird at the nest

  • Older nestling with the hood up

  • COLLECTIE TROPENMUSEUM Een jonge slangenbuizerd (Spilornis) in afweerhouding op het nest in Dampar Oost-Java TMnr 10006579.jpg
  • COLLECTIE TROPENMUSEUM Een slangenbuizerd (Spilornis) van 26 dagen oud met een slang Dampar Oost-Java TMnr 10006590.jpg

literature

Individual evidence

  1. ↑ Ferguson-Lees / Christie (2009), p. 136, see literature
  2. ↑ Ferguson-Lees / Christie (2001), p. 459, see literature
  3. ↑ a b c d e f g Ferguson-Lees / Christie (2001), p. 458, see literature
  4. ↑ Snake consecration audio sample
  5. ↑ a b Ferguson-Lees / Christie (2001), pp. 457–471, systematics, or number of subspecies according to the IOC World Bird List ( memento of December 5, 2013 in the Internet Archive ), version 3.2, accessed on January 27 2013
  6. ↑ Ferguson-Lees / Christie (2001), p. 457, see literature
  7. ↑ Ferguson-Lees / Christie (2001), pp. 73f, see literature
  8. ↑ Ferguson-Lees / Christie (2001), pp. 457f, see literature
  9. ↑ a b Ferguson-Lees / Christie (2001), p. 459, see literature

Web links

Commons : Snake Harrier  - Collection of pictures, videos and audio files