The African hawk-eagle (Aquila spilogaster) is a large bird of prey. Like all eagles, it belongs to the family Accipitridae. This species' feathered legs mark it as a member of the Aquilinae subfamily. The African hawk-eagle breeds in tropical Sub-Saharan Africa. It is a bird of assorted woodland, including both savanna and hilly areas, but they tend to occur in woodland that is typically dry. The species tends to be rare in areas where their preferred habitat type is absent. This species builds a stick nest of around across in a large tree. The clutch is generally one or two eggs. The African hawk-eagle is powerfully built and hunts small to medium-sized mammals and birds predominantly, occasionally taking reptiles and other prey as well. The call is a shrill kluu-kluu-kluu. The African hawk-eagle is listed as Least Concern by the IUCN,
Taxonomy
The African eagle is a member of the Aquilinae or booted eagles. This is a rather monophyletic subfamily of approximately 38 species are classified in the subfamily, all bearing the signature well-feathered tarsi. The Bonelli's eagle (Aquila fasciata) was once lumped within the same species as the African hawk-eagle. Recent DNA research has resulted in the two species being moved, in 2014, to the genus Aquila from Hieraaetus, along with a third possibly related species, the Cassin's hawk-eagle (Aquila africana). More specifically and surprisingly, Bonelli's, African hawk- and Cassin's hawk-eagles were found to be genetically closely related to the golden eagle (Aquila chrysaetos) species complex, which also includes Verreaux's eagle (Aquila verreauxii), Gurney's eagle (Aquila gurneyi) and wedge-tailed eagle (Aquila audax). These species are all rather larger and morphologically distinct (in adaptation to their generally open country habits, excepting the Gurney's) from the Bonelli's and African hawk-eagles and tend to have much more uniform and darker ventral plumages. Furthermore the four other traditional members of the Aquila genus have been revealed to be a separate species complex despite showing superficial similarity to the golden eagle group, i.e. being relatively large and long winged with usually rather uniform and dark (typically brownish) colours.
Description
The African hawk-eagle has a somewhat small head but one that protrudes quite well due its quite long neck and relatively prominent beak. Furthermore, the species possesses a longish tail, with long and somewhat slender feathered legs and has large, robust feet. The wing tips tend to fall a bit short of the tail tip. The adult African hawk-eagles has whitish coloring on the thighs and the crissum. The juvenile of the species is highly distinct from older hawk-eagles. Juveniles are moderately dark brown above with some pale edging, a slightly black-streaked head and a more clearly barred tail than adult hawk-eagles. The underside has a tawny-rufous base colour. When juvenile African hawk-eagles present black shaft streaks below they are usually only obvious on the flanks and they can border on being absent. The eyes of adult hawk-eagles are rich yellow while those of juveniles are hazel-brown while the cere and feet at all ages range from dull to somewhat brighter yellow. In flying juveniles, if seen from above, the contrasting creamy window, as in the adults, and barred tail stand out as the most distinct features of the species. Below, the juvenile African hawk-eagles show rufous wing linings that match the forebody and rather varying dusky edges, which often form carpal arcs and sometimes continuing as wing diagonals. The wings are otherwise rather nondescript in juvenile African hawk-eagles with greyish buff secondaries and tail thinly barred and white-based primaries. Mean length of a male may be around while the mean length of a female may be around . Wingspan among this species may vary from . In one sample, 14 males were found to have averaged while a sample of 10 males averaged . Among standard measurements, the wing chord of males measures from while that of females is from . African hawk-eagles measure in tail length from and, in a limited sample, in tarsus length from . The talon size is extremely large for this raptor's size, being similar to that of some eagles that are around twice as heavy such as eastern imperial eagles (Aquila heliaca).
Identification
thumb|left|A juvenile African hawk-eagle. Before they attain the pied appearance of adults, juveniles of the species appear as a somewhat nondescript rufous raptor.
The African hawk-eagle is largely allopatric from the most similar extant species of eagle, its sister species, the Bonelli's eagle. However, they may need to be distinguished in the Red Sea area, where minimal range overlap occurs. The Bonelli's eagle is larger and relatively broader-headed, shorter-necked, with proportionately longer wings and a shorter tail. The adult Bonelli's is much lighter and browner dorsally with usually a white patch on the mantle but no paler wing panels above. The Bonelli's eagle tends to be less contrastingly marked below, being rather creamy and lacking strong markings. The juvenile Bonelli's is a bit more similar to the juvenile African hawk-eagle but can be told apart by proportions and by being paler backed and again lacks the clear "windows" of the juvenile hawk-eagle. There are a few other largely black dorsally and white ventrally largish raptors in sub-Saharan Africa but the African hawk-eagle is the largest and comes the closest to being typically aquiline in bearing and morphology. One species sometimes considered rather similar is the adult Ayres's hawk-eagle (Hieraaetus ayresii) but that hawk-eagle is smaller, more compact as well as being rounder headed. The Ayres's may show a nuchal crest and also lacks the windows seen on the wing upperside and is more evenly blotched or streaked all over the underbody, wing linings and legs. Additionally, the Ayres's hawk-eagle is less heavily darkly marked on the wings, being more spotted and splotched with black, lacking black trailing wing edges as well as the subterminal tail band of the African. Juvenile Ayres's can be similar in flight below to the juvenile African hawk-eagle but is usually paler rufous with darker quills and is generally much paler above with whitish scaling and rufous crown and mantle. Moreover, in all plumages, the Ayres's show white "landing lights", reminiscent of a booted eagle (Hieraaetus pennatus). The main call may be repeated or develop into klu-klu-klu-kleeee or kluu-kluu-kluu with variations. This extended call may be given both during courtship and in moments of aggression, such as when driving away other raptors near their nest. The African hawk-eagle is rare in West Africa, leading to a lack of study. Here the species may be found into southern Senegal, The Gambia, Guinea-Bissau, eastern Guinea, northernmost Sierra Leone, Côte d'Ivoire, Burkina Faso, the northern portions of Ghana, Togo and Benin and north-central Nigeria. In central and East Africa, the range of the African hawk-eagle includes southern Chad, southern Sudan, where they tend to be fairly rare, South Sudan, west Somalia, the central and southern portions of the Democratic Republic of the Congo and essentially all of Uganda, Kenya and Tanzania. This species is found throughout the northern nations (within favorable habitats) of southern Africa including Angola, Zambia, Mozambique, Malawi, Zimbabwe, north-central Namibia, northern and eastern Botswana and northeastern South Africa, north of the Orange River. The species is gone or nearly so from Eswatini, with the last confirmed breeding having been in 2002. Despite claims of the species as far as the Cape Province in South Africa, this is almost certainly due to records of vagrants and no population likely exists in southern South Africa. As confirmed in study from Zimbabwe, more enclosed woodlands were avoided in favor of lower density woodlands. Overall, they tend to prefer fairly dry areas, but based on data from West Africa, Kenya and Botswana tend to prefer some moderate rainfall, with highly rainy areas such as Kenyan highlands tending to be avoided but also highly arid localities are avoided. Access to waterways, typically rivers, including ephemeral ones, and watering holes, is not infrequent, especially since they permit tall trees in otherwise fairly dry regions of Africa and also often hold concentrations of prey. Secondarily, they may be seen in fairly open, sparser savanna and assorted semi-desert areas whilst they generally avoid evergreen forests and mountainous areas. However, this species typically seems to require protected areas to successfully propagate in. The African hawk-eagle has been documented from sea level to around , but mainly occurs below . Mostly the African hawk-eagle engages in still-hunting, wherein they scan from prey from an inconspicuous perch for a long period. When prey is spotted, the hawk-eagle engages in a low level dash from their perch in cover. One tandem hunting pair of African hawk-eagles appeared to remarkably make use of a mesh fence to drive guineafowl into in a cunning strategy to prevent their escape. Yet another pair of African hawk-eagles appears to derive much of its prey by regularly and opportunistically perching in a tree holding a fruit bat colony.
A trained African-hawk eagles can habitually kill European hares (Lepus europaeus) around in weight, and one eagles around kills a large male domestic cat (Felis catus) around . However, what is known suggests that this is an exceptionally powerful predator that may nearly rival much larger eagles such as martial eagles (Polemaetus bellicosus) in its ability to take large and middle-sized prey. Both Zimbabwe studies shows that African hawk-eagles would habitually take mammalian prey larger than itself, including scrub hares (Lepus saxatilis ) of an estimated average of , and yellow-spotted rock hyrax (Heterohyrax brucei) and rarely Cape hyrax (Procavia capensis), of around with weights of infrequently up to . In Botswana, the main prey appeared to be hornbills, with one nest found to contain 25 southern yellow-billed hornbills (Tockus leucomelas) and only 5 southern red-billed hornbills (Tockus rufirostris) while elsewhere in the Zambezi Escarpment, the red-billed hornbills dominated the diet. Domestic chickens (Gallus gallus domesticus) are sometimes taken in cultivated areas by African hawk-eagles, but the species is not thought to be as much of a poultry killer as it is made out to be. Larger mammals may include assorted species of mongoose to as large as the banded mongoose (Mungos mungo) and hare to as large as scrub hares, in many cases these may be as heavy or heavier than the hawk-eagle itself. Besides smaller antelopes like dik-diks, the young of a few antelope are known to have been attacked by African hawk-eagles: klipspringers (Oreotragus oreotragus), steenboks (Raphicerus campestris) and lechwes (Kobus leche), the latter prey weighing an estimated and so perhaps the largest prey credited to the African hawk-eagle (although occasional adult dik-diks of up to a similar weight may also be attacked). Predation on reptiles seems to be fairly uncommon and few such prey are definitively identified, but both colubrid snakes and cobras are known to be included in their prey spectrum as well as lizards such as chameleons and giant plated lizards (Gerrhosaurus validus). Nesting is ultimately timed to line up with the regional dry season. Rarely to exceptionally, nests may be placed elsewhere other than a tree. Nesting locations typically provide some shade but some nest sites are rather exposed, necessitating the shading of the eaglet by the female, even to a period longer than the nesting period. In terms of developmental growth, at 5 days old, nestling African hawk-eagles are just barely able to preen themselves and by 11 days can move slightly around the nest. Young eaglets spend a great deal of the day sleeping and most awake activity involves preening and feeding. Only at the age of 24 days can the chicks defend the nest, stand reasonably well and make a few rather clumsy wing exercises; however at this stage they cannot tear meat off of the food that a parent provide. When the eaglet is 32 days old it is mainly attended to for feeding, stands well and exercises wings. At 50 days of age, the chicks show signs of fledging through being able to feed themselves and through flapping their wings. Around this stage they may preen quite a lot, nibble on sticks of the nest and make mock kills of prey bones and of sticks. Some of these activities are said to improve coordination. Fledgling begins at between 60 and 70 days of age, reports of as little as 41 days for fledgling are probably dubious. Post-nesting attachment to parental care is not long for a tropical raptor, typically lasting about 3 to 4 weeks. Thereafter, the young African hawk-eagle may be seen farther afield but then again some are seen in the company of their parents for as long as 2 months after fledging. The smaller chick typically has little chance of survival given the size differences of the two. In one case, the younger one weighed upon hatching, when its sibling was already , in another case the weights at the corresponding ages were and . According to a 1959 study, the instinct for two chicks to fight subsides after a few weeks thus if the second chick manages to survive for that long, the chances that it will fledge will be increased. The same paper suggests that intrabrood cannibalism likely follows a siblicide event. No cases of two successfully raised young were documented in southern Africa by the 1980s but two fledglings have been claimed produced in about 20% of Kenyan nests. The mean distance for African hawk-eagles from their ringing as nestlings to recovery was in southern Africa. Similarly an adult hawk-eagle found dead in the Matobos was only away from its natal site. A 2006 study found that the African hawk eagle, among other raptor species have been declining at high rates outside of protected areas in West Africa and only seem to be stabilizing through the efforts of national parks. When numbers from 2003 to 2004 are compared to 1969-1973 in West Africa, it is found that numbers have declined even in protected areas. Overall negative population trends have also been detected for some time in southern Africa. Despite claims that declines in Malawi are due to persecution of the African hawk-eagle as a poultry thief, the much stronger cause is likely to be the pervasive destruction of woodlands.