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 the booted eagle subfamily (Aquilinae), it has feathers over its tarsus. One of the largest and most powerful species of booted eagle, it is a fairly opportunistic predator that varies its prey selection between mammals, birds and reptiles. It is one of few eagle species known to hunt primarily from a high soar, by swooping down on its quarry.Steyn, P. (1983). Birds of prey of southern Africa: Their identification and life histories. Croom Helm, Beckenham (UK). 1983. This species, an inhabitant of wooded belts of otherwise open savanna, has shown a precipitous decline in the last few centuries due to a variety of factors. The martial eagle is one of the most persecuted bird species in the world. Due to its habit of taking livestock and regionally valuable game, local farmers and game wardens frequently seek to eliminate martial eagles, although the effect of eagles on this prey is almost certainly considerably exaggerated. Currently, the martial eagle is classified with the status of Endangered by the IUCN.Simmons, R.E. (2005). Martial Eagle Polemaetus bellicosus. Roberts' Birds of southern Africa, 7th edition. Hockey, PAR, Dean, WRJ and Ryan, PG (eds), 538-539.Cloete, D. (2013). Investigating the decline of the Martial Eagle (Polemaetus bellicosus) in South Africa. University of Cape Town.
Range The martial eagle can be found in most of sub-Saharan Africa, wherever food is abundant and the environment favourable. With a total estimated distribution of about , it has a substantial distribution across Africa, giving it a somewhat broader range than other species there like the crowned eagle (Stephanoaetus coronatus) and the Verreaux's eagle (Aquila verreauxii).BirdLife International (2017) IUCN Red List for birds. Downloaded from Although never common, greater population densities do exist in southern Africa and in some parts of east Africa. Martial eagles tend to be rare and irregular in west Africa but are known to reside in Senegal, The Gambia and northern Guinea-Bissau, southern Mali and the northern portions of Ivory Coast and Ghana. From southern Niger and eastern Nigeria the species is distributed spottily through Chad, Sudan and the Central African Republic as well as the northern, eastern, and southern portions of the Democratic Republic of the Congo. In east Africa, they range from Somaliland and Ethiopia more or less continuously south through Kenya, Uganda, Tanzania and in southern Africa from Angola, Zambia, Malawi and southern Mozambique to South Africa. Some of the larger remaining populations are known to persist in Zimbabwe and South Africa. Generally, these birds are more abundant in protected areas such as Kruger National Park and Kgalagadi Transfrontier Park in South Africa, or Etosha National Park in Namibia.Boshoff, A.F. Martial eagle Polemaetus bellicosus. In: Harrison JA, Allan DG, Underhill LG, Herremanns M, Tree AJ, Parker V, Brown CJ, editors. The atlas of southern African Birds, vol 1. (1997). Randburg: BirdLife South Africa. 192-3.
Taxonomy
The Accipitridae family (hereafter accipitrids) is by far the most diverse family of diurnal raptors in the world, with more than 230 currently accepted species.Kemp, A.C. (1994). Martial Eagle (Polemaetus bellicosus). Pp. 200-201 in: del Hoyo, Elliott & Sargatal. eds. (1994). Handbook of the Birds of the World, vol. 2. As a member of the booted eagle subfamily, Aquilinae, the martial eagle is one of the roughly 15% of extant species in the family to have feathers covering its legs. This helps distinguish these species from other eagles and raptors, as they are present even in tropical species such as the martial eagle.Brown, L. & Amadon, D. (1986). Eagles, Hawks and Falcons of the World. The Wellfleet Press. . Under current classifications, booted eagles consist of approximately 38 living species that are distributed in every continent inhabited by the accipitrids, which excludes only the continent of Antarctica. Just under half of the living species of booted eagle are found in Africa.Amadon, D. (1982). The genera of booted eagles: Aquila and relatives. Journal of the Yamashina Institute for Ornithology, 14(2-3), 108-121.Lerner, H., Christidis, L., Gamauf, A., Griffiths, C., Haring, E., Huddleston, C.J., Kabra, S., Kocum, A., Krosby, M., Kvaloy, K., Mindell, D., Rasmussen, P., Rov, N., Wadleigh, R., Wink, M. & Gjershaug, J.O. (2017). Phylogeny and new taxonomy of the Booted Eagles (Accipitriformes: Aquilinae). Zootaxa, 4216(4), 301-320. Studies have been conducted on the mitochondrial DNA of most booted eagle species, including the martial eagle, to gain insight on how the subfamily is ordered and which species bear relation to one another. DNA testing in the 1980s indicated the martial eagle was a specialized off-shoot of the small-bodied Hieraaetus eagles, and one study went so far as to advocate that the martial eagle be included in the genus. However, more modern and comprehensive genetic testing has shown that the martial eagle is distinct from other living booted eagles and diverged from other extant genera several million years ago.Lerner, H.R., & Mindell, D.P. (2005). Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics and Evolution, 37(2), 327-346. Genetically, the martial eagle fell between two other species in monotypical genera, the African long-crested eagle (Lophaetus occipitalis) and the Asian rufous-bellied eagle (Lophotriorchis kienerii), that similarly diverged long ago from other modern species. Given the disparity of this species' unique morphology and the fact that the two aforementioned most closely related living species are only about as large as the bigger buzzards, the unique heritage of the martial eagle is evident.
There are no subspecies of martial eagle, and the species varies little in appearance and genetic diversity across its distribution.
Description
The martial eagle is a very large eagle. In total length, it can range from , with an average of approximately .Redman, N., Stevenson, T., & Fanshawe, J. (2010). Birds of the Horn of Africa: Ethiopia, Eritrea, Djibouti, Somalia and Socotra. Bloomsbury Publishing. Its total length – in comparison to its wingspan – is restricted by its relatively short tail. Nonetheless, it appears to be the sixth or seventh longest extant eagle species. The wingspan of martial eagles can range from .Polemaetus bellicosus- University of Michigan Species ProfileSinclair, I., Hockey, P., Tarboton, W., Ryan, P., & Perrins, N. (2020). Sasol birds of southern Africa. Penguin Random House South Africa. Wingspans of as much as have been reported but may be unsubstantiated.Grambo, R. L. (1999). Eagles. Voyageur Press.van Rooyen, C. (2008). Bird impact assessment study. Average wingspans have been claimed of and for the species, however ten measured martial eagles in the wild were found to average in wingspan. Thus, the martial eagle appears to average fourth in wingspan among living eagles, behind only the Steller's sea eagle (Haliaeetus pelagicus), the white-tailed eagle (Haliaeetus albicilla) and the wedge-tailed eagle (Aquila audax), in roughly that order.Mendelsohn, J.M., Kemp, A.C., Biggs, H.C., Biggs, R., & Brown, C.J. (1989). Wing areas, wing loadings and wing spans of 66 species of African raptors. Ostrich, 60(1), 35-42.Saito, K. (2009). Lead poisoning of Steller's Sea-Eagle (Haliaeetus pelagicus) and White-tailed Eagle (Haliaeetus albicilla) caused by the ingestion of lead bullets and slugs. Hokkaido Japan. In RT Watson, M. Fuller, M. Pokras, and WG Hunt (Eds.). Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. For a species that is fairly homogeneous in its genetic make-up, the body mass of martial eagles is surprisingly variable. To some extent, the variation of body masses in the species is attributable to considerable reverse sexual dimorphism as well as varying environmental conditions of various eagle populations.Biggs, H.C., Kemp, A.C., Mendelsohn, H.P. & Mendelsohn, J.M. (1979). Weights of South African Raptors and Owls. Durban Museum Novitates, 12: 73-81. Unsexed martial eagles from various studies have been found to have weighed an average of in 17 birds, in 20 birds and in 20 birds while the average weight of martial eagles shot by game wardens in the early 20th century in South Africa was listed as .Bright, J.A., Marugán-Lobón, J., Cobb, S.N., & Rayfield, E.J. (2016). The shapes of bird beaks are highly controlled by nondietary factors. Proceedings of the National Academy of Sciences, 113(19), 5352-5357.Stevenson-Hamilton, J. (1954). Wild life in South Africa. Cassell and Co., London. In weight range, the martial eagle broadly overlaps in size with the golden eagle (Aquila chrysaetos) and Verreaux's eagle (and is even exceeded by them in maximum known body mass). Based on numerous studies, the martial eagle appears to be mildly heavier than the Verreaux's eagle but (derived from the globally combined body mass of its various races), the mean body masses of golden and martial eagles are identical at approximately . This renders the golden and martial eagles as tied as the largest African eagles (by body mass but not in total length or wingspan, in which the martial bests the golden), as well as the heaviest two species of booted eagle in the world and as tied as the sixth heaviest eagles in the world, after the three largest species of sea eagle (Steller's being the heaviest extant, the others ranking 4th and 5th), the harpy eagle (Harpia harpyja) and the Philippine eagle (Pithecophaga jefferyi). The longest African eagle (and second longest booted eagle after the wedge-tailed eagle (Aquila audax)) is the crowned eagle by virtue of its relatively longer tail, as its body weight is slightly less than these three heaviest booted eagle species.
Sexual dimorphism