The African harrier-hawk or gymnogene (Polyboroides typus), is a large species of bird of prey found throughout most of sub-Saharan Africa. It is only one out of two species of harrier-hawk, the other one being the very similar Madagascar harrier-hawk (Polyboroides radiatus). The harrier-hawks are closely related to the harriers. The African harrier-hawk grows to a length of 60-66 cm (23.5-26 in) and can get a wingspan up to 160 cm (5 ft 3 in). It is an unmistakable bird with its all grey appearance, yellow to orange face and beak, and long yellow legs. Upperparts are a uniform grey, while the underparts are all white with very fine black barring, making it a grey appearance from a distance. This white and black barring stretches on to the underwing coverts. Flight feathers are grey with a broad black line edging the wings. A fine white line separates the grey and black. Tail is all black with a single broad white band. Its markings often makes it very easy to identify in flight. Juveniles have a plumage in various shades of brown, with barred tail and flight feathers. It takes three years to reach adult plumage.
African harrier-hawks are found in various habitats, but prefers forests, woodland savannahs, and riparian habitats. They are also found in mountainous areas in elevations up to 3,000 meters (9,800 ft). This species has adapted well to human interference, and does fine in cultivated and urban environments.
Hunting and diet
The African harrier-hawk is known for its remarkable and different way of hunting. Although it can hunt like normal raptors, either in low flight or from a perch, it often actively hunt prey by climbing around in trees. It is not uncommon to see African harrier-hawks hanging from branches or tree trunks, sometimes upside-down, as they search for prey. They will also jump from branch to branch or run along larger branches, with wings flapping to keep the balance, as they seek out prey. This peculiar climbing behavior is made possible due to its double-jointed knees that make its legs incredibly flexible. Diet is varied, but it is specialized on tree-dwelling animals, such as birds, reptiles and mammals, which are often captured in tree cavities and crevices. Bird’s nests are also frequently raided. Insects, carrion, and oil palm fruits are also eaten on occasion.
Breeding season varies within its geographical range. It is a monogamous species (although there was one instance where three adults were seen on one nest) and it is highly territorial. Nests are built by both parents in a period of around 30 days. It is a fairly large nest, made up of twigs and sticks, and is either situated high up in a tree, on a cliff, or in a cave. Nests from other species, such as the martial eagle and black goshawk, may sometimes be used.
One to three eggs are laid and incubated by the female for 35-36 days, while the male hunts and provides food. After hatching, the female will stay with the chicks at the nest for one week while the male keeps bringing food. After this she will stay close to the nest for protection. It is common for the oldest chicks to kill the youngest in a nest, and often only one or two survive, depending on the clutch size. After 45-55 days the chicks leave the nest. They will be fully independent after another 10 days.