The African harrier-hawk, harrier hawk or gymnogene (''Polyboroides typus'') is a

bird of prey Birds of prey or predatory birds, also known as (although not the same as) raptors, are hypercarnivorous bird species that actively predation, hunt and feed on other vertebrates (mainly mammals, reptiles and smaller birds). In addition to speed ...

. It is about in length. It breeds in most of

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

south of the

Sahara The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in the world and the list of deserts by area, third-largest desert overall, smaller only than the deserts of Antarctica and the northern Ar ...

. The only other member of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

is the

allopatric Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

Madagascar harrier-hawk The Madagascar harrier-hawk (''Polyboroides radiatus'') is a medium-sized species of bird of prey in the family Accipitridae, endemic to Madagascar. Description The Madagascar harrier-hawk is a medium-sized raptor with long and broad wings which ...

(''Polyboroides radiatus'').

Description

left, 165px, Adult hunting at a weaver colony in Etosha National Park, Namibia 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, usually red or yellow. Sexes are similar, but young birds have pale brown instead of grey, and dark brown replacing black. An unusual trait of this species is the double-jointed ankles it possesses, which enable it to reach into otherwise inaccessible holes and cracks for prey. A comparable leg-structure and behaviour can be found in the

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

crane hawk as well as the extinct

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

n '' Pengana''; a case of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. The call is a whistled '.

Distribution and habitat

African harrier-hawks are a common raptorial species south of the

being most commonly found in the tropical regions of western

becoming less common in East and

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. African harrier-hawks are adaptable in their habitat preferences, occupying the following habitats in the Dzanga-Sangha Special Reserve in the

Central African Republic The Central African Republic (CAR) is a landlocked country in Central Africa. It is bordered by Chad to Central African Republic–Chad border, the north, Sudan to Central African Republic–Sudan border, the northeast, South Sudan to Central ...

: thick

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

, forest edge,

riparian A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripar ...

areas, agricultural land and human occupied areas. African harrier-hawks are adaptable and able to live in both urban and rural human occupied areas and they are one of the most common raptorial species in traditional

rural In general, a rural area or a countryside is a geographic area that is located outside towns and cities. Typical rural areas have a low population density and small settlements. Agricultural areas and areas with forestry are typically desc ...

villages of eastern

Guinea-Bissau Guinea-Bissau, officially the Republic of Guinea-Bissau, is a country in West Africa that covers with an estimated population of 2,026,778. It borders Senegal to Guinea-Bissau–Senegal border, its north and Guinea to Guinea–Guinea-Bissau b ...

. African harrier-hawks have also been known to breed in Palm trees present in cities and

urban Urban means "related to a city". In that sense, the term may refer to: * Urban area, geographical area distinct from rural areas * Urban culture, the culture of towns and cities Urban may also refer to: General * Urban (name), a list of people ...

gardens.

Biology

Breeding

Breeding season

The breeding season starts at different times in different parts of African harrier-hawk distribution. In

Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...

the breeding season is in March–August and South of the

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

it appears that the breeding season is in the

austral summer Summer or summertime is the hottest and brightest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, daylight hours are the longest and darkness hours are the shortest, with day ...

but can vary in the months of different countries in South Africa it is November–December but in

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

Malawi Malawi, officially the Republic of Malawi, is a landlocked country in Southeastern Africa. It is bordered by Zambia to the west, Tanzania to the north and northeast, and Mozambique to the east, south, and southwest. Malawi spans over and ...

and

Zimbabwe file:Zimbabwe, relief map.jpg, upright=1.22, Zimbabwe, relief map Zimbabwe, officially the Republic of Zimbabwe, is a landlocked country in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Bots ...

it is September–November.

Nests and nesting

Nest sites are most commonly in large trees that are sometimes growing out of or located on a rocky outcrop. Nests are circular and often placed in the main fork of the tree and are below the

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...

. Nests can be used for several breeding seasons and are relatively big as are other raptors' reaching estimated sizes of 0.75m wide and 0.2m deep. Nests are made of sticks and are lined with leaves from trees neighbouring the nest. The clutch is one to three eggs.

Courtship

In the courtship display for African harrier-hawks, either one of or both individuals in a pair soar slowly together, at height, and can often be heard calling during this time. When the male flies on his own he often flies in an undulating pattern and flaps his wings. When the pair fly together, there have been records of the male diving towards the female and touching her back with his talons, and the female turning over and touching talons with the male.

Foraging

Diet

The African harrier-hawk is omnivorous, eating the fruit of the

oil palm ''Elaeis'' () is a genus of palms, called oil palms, containing two species, native to Africa and the Americas. They are used in commercial agriculture in the production of palm oil. Description Mature palms are single-stemmed, and can gro ...

as well as hunting small vertebrates. Its ability to climb, using wings as well as feet, and its long double-jointed legs, enable this bird to raid the nests of cavity-nesters such as barbets and

woodhoopoe The wood hoopoes or scimitarbills are a small African family, Phoeniculidae, of near passerine birds. They live south of the Sahara Desert and are not migratory. While the family is now restricted to Sub-Saharan Africa, fossil evidence shows th ...

s for eggs and nestlings. It has been known to prey on introduced species such as

feral pigeon Feral pigeons are birds derived from domesticated populations of the rock dove ''Columba livia'', descendants that have escaped and are living independently from (and often unwanted by) humans, having gone "feral". They are sometimes given the ...

house sparrow The house sparrow (''Passer domesticus'') is a bird of the Old World sparrow, sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pa ...

s and eastern gray squirrels.

Foraging techniques

African harrier-hawks have been identified to employ four different hunting strategies namely: low soaring, high soaring, perch hunting and,

and ground foraging. Low soaring is the most commonly used method.The harrier-hawk flies close to the canopy and is often mobbed by small

passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped') which includes more than half of all bird species. Sometimes known as perching birds, passerines generally have an anisodactyl arrangement of their ...

birds. The African harrier-hawk uses the level of aggression shown to help locate nest sites of these passerines and has been observed to turn around when the mobbing by a passerine becomes less aggressive. The harrier-hawk will begin looking for nest sites in the trees once it has found the area where the passerines show the most aggression towards the African harrier-hawk. To catch reptiles in the open African harrier-hawks use high soaring, flying at a maximum of 100m. They descend quickly to a height just above that of the vegetation to where the prey was located. Perch hunting is often used to hunt

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s such as

orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – gras ...

and other insects. Canopy and ground foraging is where the harrier-hawk either walks on the ground or moves between branches in the canopy looking for prey, looking into crevices and holes in both trees and on the ground.

Gallery

File:African Harrier-hawk (Polyboroides typus) (21646641084).jpg, Immature bird in flight, Zambia File:Immature African harrier-hawk (gymnogene), Polyboroides typus, at Ndumo Nature Reserve, KwaZulu-Natal, South Africa (28901676521).jpg, Immature bird lifting tree bark, South Africa File:African harrier-hawk (Polyboroides typus typus) taking off, crop.jpg, Adult taking flight, Zimbabwe File:Polyboroides typus -Lake Nakuru National Park, Kenya-8 (2).jpg, Adult investigating a tree cavity, Kenya File:Martial eagle (Polemaetus bellicosus) in flight with African harrier-hawk (Polyboroides typus) composite.jpg, Adult soaring alongside a martial eagle (''

Polemaetus bellicosus The martial eagle (''Polemaetus bellicosus'') is a large eagle native to sub-Saharan Africa.Ferguson-Lees & Christie, ''Raptors of the World''. Houghton Mifflin Company (2001), . It is the only member of the genus ''Polemaetus''. A species of t ...

)'', Zimbabwe File:Entebbe Botanical Gardens 3.jpg, African harrier hawk (Polyboroides typus) in Botanical Gardens, Entebbe, Uganda File:African harrier-hawk (Polyboroides typus) Kruger.jpg, showing tail feathers, South Africa

References

External links

* (African harrier-hawk = ) Gymnogene
Species text in The Atlas of Southern African Birds
{{DEFAULTSORT:harrier-hawk, African

African harrier-hawk The African harrier-hawk, harrier hawk or gymnogene (''Polyboroides typus'') is a bird of prey. It is about in length. It breeds in most of Africa south of the Sahara. The only other member of the genus is the allopatric Madagascar harrier-hawk ...

Taxa named by Andrew Smith (zoologist)