Polemaetus bellicosus
martial eagle

Martial eagles (Polemaetus bellicosus) are found throughout Sub-Saharan Africa, although they avoid dense forests and are absent from much of central Africa. (Burton and Burton, 2002; Machange, et al., 2005)

Martial eagles prefer open habitats including savanna, steppe, semidesert and scrubby woodlands. These eagles require trees for nesting and are absent from arid or cleared areas, although there have been cases of martial eagles in the Karoo region of South Africa using power line supports to form nests. Martial eagles are spread sparsely throughout their geographical range punctuated with pockets of higher densities found in large protected areas, especially in South Africa and Zimbabwe. They can be found at all altitudes under 3000 meters. (Burton and Burton, 2002; Machange, et al., 2005; Thiollay, 1994; de Goede and Jenkins, 2001)

Martial eagles are Africa’s largest eagle. Adults range in size from 78 to 96 cm in length, weighing between 3.1 and 6.2 kg, with a wingspan from 188 to 260 cm. The males are slightly smaller than females (76% of the size). The adults have brown upper-parts and have a short dark crest. The underparts are white with brown to black spots that extend to feathered legs. The bill is long, strongly hooked and black. The toes are bluish gray and armed with large curved talons. The wings are long and slightly pointed with dark tips and dark under-wing coverts, although the flight feathers are barred. The tail is short, lighter in appearance, and is also barred. Females have more spots on the underparts than males do. Juveniles have pale to white upper-parts and have pale wings with light under-wing coverts. (Burton and Burton, 2002; Ferguson-Lees and Christie, 2001; Thiollay, 1994)

Martial eagles lack a mating dance although both sexes will make a loud, distinctive cry during mating periods. They form monogamous pairs and reportedly mate for life. (Burton and Burton, 2002)

Martial eagles nest in large trees or pylons often located on hill sides. The nest is a large structure (4 – 6 feet in diameter) made of sticks up to 1.5 inches in diameter and lined with green leaves. Pairs may build multiple nests (up to 7 nests in a given territory) and alternate between nests on successive years. The nests are often re-used from year to year with the female repairing parts of the structure and re-lining the interior with leaves. Mating seasons vary across the geographic range, although it generally occurs during the dry season: from February until November in South, Central and East Africa, from August till January in North East Africa, and in November in West Africa. Martial eagles more often breed once every two years, than once every year.

The female lays generally 1, sometimes 2 eggs. Incubation lasts for 45 to 50 days, and chicks fledge 90 to 100 days after hatching. Juveniles remain close to the nest for up to 6 months, and do not reach full independence until 2 to 3 years of age. Martial eagles reach reproductive maturity at 4 to 5 years of age. (Allan, 1996; Burton and Burton, 2002; Machange, et al., 2005; Simmons and Brown, 2006; Thiollay, 1994)

The female incubates the egg for the 45 to 50 days it takes for a chick to hatch, although males have been observed incubating. Males rarely bring food to incubating females until the egg hatches, after which males will hunt and feed females for approximately 2 months. Chicks are born without feathers and become fully fledged after 90 days, and after which they attempt their first flight. Juveniles spend several years in the nest region before being chased off by the adults. (Brown, 1966; Burton and Burton, 2002; Thiollay, 1994)

In the wild, martial eagles are expected only to live an average of 14 years, although one individual was recaptured 25 years after being banded. (Brown, 1966; Burton and Burton, 2002)

Martial eagles spend most of the time hunting or soaring high above the ground (generally invisible to the naked eye). With their large wings and broad tail they are excellent at soaring, although poor at maneuvering which helps explain why they avoid dense forests. These eagles hunt by attacking in a well controlled dive at a slanted angle and striking prey with their long legs. They often perch on dead branches and trees that give a wide view of the areas and generally return to these perches when resting. Although uncommon, they have been observed hunting from a perched position. Martial eagles are shy and often avoid humans. (Allan, 1996; Burton and Burton, 2002; Simmons and Brown, 2006; Thiollay, 1994)

A pair of adults can occupy a range up to 300 square kilometers, although in high densities a pair's territory is often less than 20 square kilometers. (Machange, et al., 2005; Thiollay, 1994)

Martial eagles are silent for most of the year, although during mating season they cry kwi-kwi-kluee-kluee. Like all birds, martial eagles perceive their environment through visual, auditory, tactile, and chemical stimuli. (Burton and Burton, 2002)

Martial eagles eat a variety of medium sized mammals, birds, and lizards generally weighing between 1 – 5 kilograms, determined by whatever is available in their territories, including animals much larger than 5 kilograms. In a study in the Cape Province of South Africa, Cape hares (Lepus capensis) were the dominant prey making up 50% of all kills, followed by striped polecats (Ictonyx striatus), genets (Genetta tigrina and G. genetta), ground squirrels (Xerus inauris) and mongooses (Mungos mungo, Helogale parvula, Herpestes ichneumon, and Galerella sanguinea). In some cases game birds and waterfowl make up a large portion of their diet. These include primarily francolins (Francolinus species), bustards (Otididae), and guinea fowls (Numidae). In other areas, martial eagles prey primarily upon rock hyraxes (Procavia capensis). To a lesser extent, martial eagles have hunted: Vervet monkeys (Chlorocebus pygerythrus), baboons (Papio species, especially P. Anubis), small antelopes including: Thomson’s gazelles (Eudocas thomsoni), young impala (Aepyceros melampus), duikers (Cephalopus species), jackals (Canis species), snakes, and monitor lizards (Varanus niloticus, V. exanthematicus). These eagles have been seen killing and eating prey up to 35 kilograms. (Boshoff, et al., 1990; Machange, et al., 2005; Thiollay, 1994)

There are no known occurrences of predation on martial eagles, although humans will kill martial eagles if they are perceived as pests. (Machange, et al., 2005)

Martial eagles are apex predators and can be used as an indicator of ecosystem health. They also likely keep prey populations in check. (Machange, et al., 2005; de Goede and Jenkins, 2001)

While the results are not clear, it has been suggested that in the Karoo region of South Africa, martial eagles benefit small-stock farmers by managing populations of small grazing mammals that compete with their own domestic grazing animals. In general though, these eagles are very rare outside of protected areas and avoid humans. (Burton and Burton, 2002; de Goede and Jenkins, 2001)

Martial eagles are thought to be the most severely persecuted raptor in South Africa since it sometimes feeds on domesticated poultry, small lambs, and goats. However, a study in Nambia reported these predations make up a small portion (< 1%) of an eagles diet even in areas dominated by small ranchers. Unfortunately, many farmers use poison to ward off predators and many eagles are harmed in this non-specific, deadly method. (Boshoff, et al., 1990; Machange, et al., 2005; de Goede and Jenkins, 2001)

According to the IUCN Red List, martial eagles are near threatened and their populations are declining throughout their geographic range. Locally, West Africa populations are declining and their presence is rare. In Namibia, martial eagles are endangered due to a decline of 80% in their population over a five year period, where there are approximately only 350 pairs in the country. The population decline can be attributed to shooting and poisoning from local farmers and ranchers, electrocution from nesting on power lines, drowning from attempting to drink at steep-sided reserves, and starvation from the extermination of common food sources. (Burton and Burton, 2002; Machange, et al., 2005; Simmons and Brown, 2006; Thiollay, 1994; de Goede and Jenkins, 2001)