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Aug 27 2011

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Black-chested Snake Eagle (Circaetus pectoralis)


Black-chested Snake Eagle

[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Circaetus pectoralis | [authority] A. Smith, 1829 | [UK] Black-chested Snake Eagle | [FR] Circaete a poitrine noir | [DE] Schwarzbrust-Schlangenadler | [ES] Culebrera pechinegra | [NL] Zwartborsslangarend

Subspecies

Genus Species subspecies Region Range
Circaetus pectoralis AF e, sc, s

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

Black-chested Snake-Eagle adult has black upperparts, with slight ?scaled? effect, due to pale feathers? edges. Underparts are white, except chin, throat and chest which are black. Underwing and undertail feathers are white, with narrow black bars across secondaries and tail. Head is black. Hooked bill is blackish with grey cere. Eyes are bright yellow. Long bare legs and feet are grey. Both sexes are similar. Juvenile has brown upperparts with pale feathers? edges. Flight feathers are dark brown. Underparts are paler buffy-brown, underwing coverts too. Head is paler rufous-brown with crown slightly streaked with dark brown, and some grey wash over ears. Flight feathers are white below. Subadult is almost similar to adult but sooty-brown above. Underparts are whitish, with large brown spots on upper chest, and broad rufous-brown bars on flanks and flight feathers. They reach their sexual maturity at about 3 to 4 years.

Listen to the sound of Black-chested Snake Eagle

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Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 175 cm wingspan max.: 183 cm
size min.: 63 cm size max.: 67 cm
incubation min.: 51 days incubation max.: 52 days
fledging min.: 89 days fledging max.: 90 days
broods: 1   eggs min.: 1  
      eggs max.: 1  

Range

Africa : East, Southcentral, South. Occurs from Eritrea and Ethiopia through Kenya, Tanzania, southern DRC, Zambia and Angola to southern Africa. Here it is uncommon to locally common across much of the region, largely excluding southern and central South Africa

Habitat

It is generally preferring habitats ranging from semi desert and open grassland to Karoo scrub and closed deciduous woodland

Reproduction

Probably a monogamous, territorial solitary nester. The nest is built by both sexes, consisting of a saucer-shaped structure of sticks lined with green leaves and placed in the canopy of a flat-topped Acacia or large Euphorbia, often well-concealed by foliage or mistletoe. It may also use a pylon or utility pole, seldom using a nest more than once. Egg-laying season in South Africa is from June-August, while elsewhere in southern Africa it is from March-October, peaking from June-September in Zimbabwe and from September-October in Namibia. It almost invariably lays a single egg, which is mainly incubated by the female for about 51-52 days. The chicks are brooded and fed by the female using food provided by the male, and is cared for fairly intensely for the first 25 days or so, after which the adults visit the nest more intermittently just to feed their young. It eventually leaves the nest at about 89-90 days old, usually becoming fully independent six months later, although in rare cases it can stay with its parents for roughly 18 months after fledging.

Feeding habits

It mainly eats snakes, soaring or hovering while scanning the ground for prey; once it spots something it descends in stages until it finally plunges feet first onto the prey, crushing its skull. If it inaccurately strikes a snake it may fight back, entwining itself with the bird which occasionally results in the death of both snake and raptor. Diet consists of snakes, reptiles, rodents and birds. Also Anthropods and termites may be taken.

Video Black-chested Snake Eagle

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). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds 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.
Black-chested Snake Eagle status Least Concern

Migration

Mainly nomadic, although it may regularly into Namibia and the Northern Cape in summer.

Distribution map

Black-chested Snake Eagle distribution range map

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