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.Lerner, H. R. L. & Mindell, D.P. (2005) Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics and Evolution (37) 327–346.Väli, Ü. (2002). Mitochondrial pseudo‐control region in old world eagles (genus Aquila). Molecular Ecology, 11(10), 2189-2194. The Bonelli's eagle (Aquila fasciata) was once lumped within the same species as the African hawk-eagle. However, there are several morphological differences between the two species, in addition to discrepancies in life history and their considerably allopatric distribution. Now, the two species are almost universally considered distinct species. Despite the differences between the Bonelli's eagle and the African hawk-eagle the two species are visibly similar and are still considered sister species.Kemp, A. C., P. F. D. Boesman, and J. S. Marks (2020). African Hawk-Eagle (Aquila spilogaster) , version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. 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).Clark, W. S. (2012). The eagle genus Hieraaetus is distinct from Aquila, with comments on the name Ayres’ Eagle. Bulletin of the British Ornithologists’ Club, 132, 295-298.Crochet, P. A., Raty, L., De Smet, G., Anderson, B., Barthel, P. H., Collinson, J. M., & Knox, A. G. (2010). AERC TAC’s taxonomic recommendations.Collinson, M. Splitting headaches? Recent taxonomic changes affecting the British and Western Palaearctic lists. British Birds vol 99 (June 2006), 306-323. 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 open country habits) 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.
