[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Polyboroides typus | [authority] Smith, 1829 | [UK] African Harrier-Hawk | [FR] Gymnogene d’Afrique | [DE] Hohlenweihe | [ES] Aguilucho-caricalvo comun | [NL] Kaalkopkiekendief
Polyboroides is a genus of bird of prey in the Accipitridae family. This genus has two recognized species found in Sub-Saharan Africa and Madagascar. The two species are allopatric and restricted to the Afrotropic ecozone. They are generally known as Harrier-hawks.
The African Harrier-Hawk is a medium-sized raptor. The upperparts, head and breast are pale grey. The belly is white with fine dark barring. The broad wings are pale grey with a black trailing edge fringed with a narrow white line. The tail is black with a single broad white band. There is a bare facial patch of variable colour. Sexes are similar, but young birds have pale brown instead grey, and dark brown replacing black.
Listen to the sound of African Harrier-Hawk
Copyright remark: Most sounds derived from xeno-canto
Africa : widespread
It is uncommon in the plains or the thornbush areas. In these kinds of terrain, it is likely to be seen only in the forested areas close to river systems and in areas with annual rainfall in excess of 20 inches (50 cm)
It builds a stick nest lined with sprays of green leaves in the fork of a tree or the crown of a palm tree. Sometimes it will nest on rock ledges. The clutch is one to three eggs which are incubated for about five weeks. The young flegde after another seven to eight weeks. The elder chick usually kills the younger siblings, but two chicks may fledge.
Young and eggs of small birds (particularly weaver birds and sunbirds) are the favoured food also frogs, insects, small mammals, small reptiles and bats. Oil palm fruit is also eaten when it is available, but the bird does not depend on it. When feeding on oil palm nuts it walks along the fronds, hand over hand, using its wings to steady it, and almost seeming to use the wings as hands to hold on with! It probes cracks and hollows in trees for lizards and grubs, and hangs upside-down like a tit when robbing weaver birds’ nests. With the sole exception of its West African cousin, this is the only bird of prey which regularly eats vegetable matter (oil palm nuts), and certainly the only bird of prey that can manage the extremely neat trick of bending its leg the wrong way in order to extract eggs (and sometimes young) from the nests of weaver birds and the like. The weaver bird builds a very complex nest with an entrance tunnel which makes it impossible for the gymnogene to see into it, so it feels for the eggs whilst its leg is bent in what appears to be the wrong way altogether!
Video African Harrier-Hawk
copyright: J. del Hoyo
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 appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not 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.
Resident and sedetnary but might migrate in the wet season towards the Sahel zone in west Africa. Some vagrancy observed in the outskirts of range towards suitable habitat in Southern Africa.