Aquila serpentaria bruna

Identificazione

Their plumage about the body is entirely a fairly dark, hazel brown, with some claims of a purplish sheen in certain light conditions. The body colour extends to the wings but for their contrasting unmarked flight feathers which are whitish-grey. The shortish tail, which is most easily seen in flight, is at all ages barred brown and grayish cream. The juvenile is similar in appearance and colour but tends to have very sparse white feather bases, with birds from south of the range apparently showing heavier white speckling, especially on the abdomen and head. This species has a large head and bare legs, which serve to distinguish it from other brownish medium-sized eagles in Africa, although a juvenile bateleur could be confused with one in poor light, but its colour is more varying, its eyes brown and the species has a shorter tail and shorter legs. The brown snake eagle is of medium size relative to species referred to as eagles, however it is the largest member of the Circaetus genus. Of the living species in the Circaetinae subfamily, it is similar in size to the bateleur but much smaller than the Philippine eagle. Total length is from 66 to 78 cm (26 to 31 in) and wingspan is from 160 to 185 cm (5 ft 3 in to 6 ft 1 in), though wingspans of up to 200 cm (6 ft 7 in) may possibly be attained. Known weights are between 1.5 and 2.5 kg (3.3 and 5.5 lb), with an average of around 2.05 kg (4.5 lb). Despite its fairly large size, this species has a relative small wing spread, being smaller winged than the bateleur and even the much lighter black-breasted snake eagle. The brown snake eagle's call is a hoarse, guttural hok-hok-hok-hok, usually uttered in territorial displays at conspecifics and sometimes culminating in a crowing kaaww. Pairs also call a soft kwee-oo probably as a contact call at the nest.

Tassonomia

Nome scientifico

Circaetus cinereus

Autorità

Vieillot, 1818

Ordine

Accipitriformi

Famiglia

Accipitridae

Genere

Circaetus

Areale e habitat

This species is distributed widely in Africa. In west Africa, ranges from southeastern Mauritania, Senegal, The Gambia, Guinea-Bissau, eastern and western Guinea, Sierra Leone, the northern, inland parts of Liberia, Ivory Coast, Ghana, Togo, Benin, Nigeria as well as inland in Mali and Niger. From there they range across to southern Chad, southern Sudan, South Sudan, inland in Eritrea and northern Ethiopia and central Ethiopia and in southern Somalia through much of Kenya, Uganda and the southern part of the Democratic Republic of the Congo down through southern Africa to about half of Namibia, all of Botswana and Zimbabwe and northeastern and eastern South Africa. Although it is not migratory, brown snake eagles may be somewhat nomadic, with cases of birds on territories stretching up to 200 km (120 mi) apart. Furthermore, ringed birds have been known to travel 2,100 km (1,300 mi) away (from South Africa to the Democratic Republic of the Congo). This species dwell in open woods and wooded savanna, most often preferring areas where gulley or wooded hillocks break up flat areas, apparently preferring somewhat more densely wooded areas than related snake eagles. This species may dwell at any elevation from sea level to 2,000 m (6,600 ft) high.

Migrazione

Complete migrants

Conservazione

Tendenza della popolazione

declining