African Harrier-Hawk

The African harrier-hawk (Polyboroides typus), also known as the gymnogene, is a distinctive medium-sized raptor found across much of sub-Saharan Africa. It measures about 51–68 cm in length, with a wingspan of roughly 118–152 cm and a weight of about 500–820 g. Females are generally larger and heavier than males. The only other species in the genus is the Madagascar harrier-hawk (Polyboroides radiatus).

Adults are mostly grey above, with finely barred pale underparts, a black tail crossed by a broad white band and dark flight feathers. The bare facial skin is usually yellow but can flush orange-red during display or excitement. Juveniles are mainly brown and pass through transitional plumages before acquiring full adult plumage at around three years of age.

African harrier-hawks use woodland, forest edge, wooded savanna, riverine forest, palm groves, plantations, farmland and some urban areas. Mature trees, palms, cliffs and buildings provide both nesting sites and the cavities that make their specialised hunting technique effective.

The species is less common in very arid, treeless landscapes. In moister wooded country it can remain within the same broad area year-round, while birds in drier regions may become more mobile when local conditions and food availability change.

The diet is unusually broad for a raptor. African harrier-hawks take eggs, nestlings, small birds, rodents, bats, reptiles, amphibians and large insects. Carrion, fish and fruit are also eaten, with oil-palm fruit forming a notable part of the diet in some regions.

The balance between prey types varies greatly with habitat and opportunity, reflecting a highly opportunistic feeding ecology rather than dependence on a single kind of prey.

The species is famous for climbing around trunks, branches, cliffs and buildings while searching for concealed prey. It may hang sideways or upside down, using its wings for balance as it probes tree holes, crevices and nests that most other raptors cannot reach.

This is possible because the ankle joint is exceptionally mobile. An anatomical study showed that the foot can flex far backwards and swing through roughly 90° from side to side, giving the bird remarkable freedom to reach around corners and into narrow openings. Its long bare legs and relatively small head further help when investigating cavities.

The harrier-hawk is not limited to climbing. It also hunts from perches and during low or soaring flight, switching between techniques according to habitat and prey availability.

African harrier-hawks are usually encountered alone outside the breeding context and often spend long periods perched high in trees between bouts of searching and climbing. They can also soar conspicuously above woodland and forest edge.

Movement patterns vary across the range. Many birds are broadly resident, especially in moister woodland, whereas individuals in drier regions can become more nomadic when local food conditions change.

Breeding pairs are usually monogamous and territorial around the nest. At one nest, three adult birds were observed together, a rare exception to the usual pair bond. Courtship includes soaring, calling and aerial displays, during which the bare facial skin may become more strongly orange or red.

Both adults contribute to the large stick nest, which can take about 30 days to build and is placed high in a tree or palm, on a cliff ledge or occasionally on a human-made structure. Abandoned nests of other large raptors may also be used, including those of martial eagles (Polemaetus bellicosus) and black sparrowhawks (Astur melanoleucus).

One to three eggs may be laid. Incubation lasts about 35–36 days and both parents participate. The male also plays an important role in supplying food to the female and later the chicks.

The young remain in the nest for about 45–55 days. Siblicide can occur in larger broods, with an older chick killing a younger sibling. After fledging, the young remain partly dependent on their parents for at least about another ten days.

The African harrier-hawk is classified as Least Concern on the IUCN Red List. It has a very large range, occurs in many protected areas and can also use agricultural and urban landscapes.

No reliable range-wide population estimate is available. Local pressures include persecution around poultry, trapping, disturbance or removal of nesting trees and degradation of wooded habitat, but a major decline across the entire range has not been documented.