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Aug 27 2011

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Western Banded Snake Eagle (Circaetus cinerascens)

Western Banded Snake Eagle

[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Circaetus cinerascens | [authority] von Muller, 1851 | [UK] Western Banded Snake Eagle | [FR] Circaete cendre | [DE] Band-Schlangenadler | [ES] Culebrera coliblanca | [NL] Kleine Grijze Slangearend

Subspecies

Monotypic species

Genus

Members of the genus Circaetus are the snake eagles. They form a monophyletic group Circatinae that is sister to the Old World vulture group, Aegypiinae. These are mainly birds which specialise in feeding on snakes and other reptiles, which is the reason most are named as “snake-eagles” or “serpent-eagles”. They are restricted to warmer parts of the Old World. They have hooked beaks for tearing flesh from their prey, strong legs and powerful talons. They also have extremely keen eyesight to enable them to spot potential prey from a distance.

Physical charateristics

Western banded Snake Eagle is grey-brown, with a short tail and a large head. The male adult has grey brown upper- and underparts, including underwing coverts. Belly feathers end with white tips. The flanks are finely barred with whitish. Upper flight feathers are dark grey to blackish, and contrast with paler back. Under flight feathers are white with narrow black bars.Black tail is short, with broad white band across centre, and we can see a fine white terminal band. Head is large and dark grey. Hooked bill is black, with deep yellow cere. Eyes are pale yellow. Long bare legs and stubby toes are deep yellow. Sexes are similar in size and plumage. Juvenile has paler and browner upperparts than adults, with white-edged feathers. Head, neck and breast are dark-streaked. Underparts are white with pale brown streaks, mainly on belly and thighs. Flight feathers are dark brown on upperwing, and white with brown bars on underwing. Trailing edge is broad and brown. Tail shows broad black subterminal band. Eyes, cere and legs are pale yellow. Subadult may be all dark grey-brown without any streak on underparts. Eyes, cere and legs are yellow.


wingspan min.: 110 cm wingspan max.: 120 cm
size min.: 56 cm size max.: 62 cm
incubation min.: 36 days incubation max.: 42 days
fledging min.: 52 days fledging max.: 59 days
broods: 1   eggs min.: 1  
      eggs max.: 1  

Range

Africa : West, Central, East, Southcentral. Occurs in sub-Saharan Africa from Senegal to Ethiopia, while largely absent from the lowland forests of the DRC and other west African countries, south to northern Tanzania, with a separate population from southern DRC through Angola and Zambia to southern Africa. Here it is uncommon in northern Botswana, the Caprivi Strip (Namibia), northern Zimbabwe and northern Mozambique,

Habitat

It is generally favouring riverine forest and woodland, such as tall Mopane (Colosphermum mopane) woodland in the Zambezi River valley, although it may occasionally hunt in adjacent open habitats.

Reproduction

Probably a monogamous solitary nester, performing spectacular aerial displays in which it dives straight down with its wings folded before stabilising again.
The nest is a platform of sticks with a cup set into it, lined with green leaves such as Munondo (Julbernadia globiflora). It is typically placed about 10-18 metres above ground in the canopy of a large tree. Egg-laying season is from about December-February. It lays a single egg, which is incubated for an estimated period of 36-42 days. The chick is fed by both parents, leaving the nest after roughly 56 days.

Feeding habits

It mainly eats snakes (especially arboreal ones), doing most of its hunting from a perch, where it stays immobile for hours while searching for prey. Once it spots something it glides to the ground or canopy and plucks the animal up before returning its perch to feed. Diet consists of snakes, reptiles, rodents and birds. Also Anthropods and termites may be taken.

Video Western Banded Snake Eagle

httpv://www.youtube.com/watch?v=ec2VQ-3HIf4

copyright: J. del Hoyo


Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Western Banded Snake Eagle status Least Concern

Migration

Probably sedentary in southern Africa, although it is for some reason it is more scarce in summer in Zimbabwe.

Distribution map

Western Banded Snake Eagle distribution range map

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