What Are True Eagles?

True eagles have feathered legs that extend all the way down to the feet. All the eagles belonging to the genus Aquila such as the Wahlberg’s and Tawny eagles are true eagles.

Wahlberg's Eagle - Aquila wahlbergi

©Nigel Dennis
Wahlberg's Eagle, Kruger National Park, South Africa.

In the summer, the commonest brown eagle in the Lowveld is undoubtedly the Wahlberg’s Eagle (pronounced “Val”-berg after the Swedish naturalist). Migrating to the warmer southern parts of the African continent from the central and more northerly reaches of it (inter-African migrant), the Wahlberg’s eagle comes here to breed during spring and summer. This it does upon a small platform of sticks that it re-bolsters each year and lines with green material. The same nest, usually positioned below the canopy in a main fork of a large riverine tree such as a Jackalberry or Knobthorn may be used for up to 28 years successively. Usually, however, the eagles have a selection of five different nests within their territories. Remarkably for migrant birds, Wahlberg’s eagles remain paired with the same mate for years. 

The Wahlberg’s eagle is small and has a long, square tail when it is perched or in flight. In flight, it also carries its head lower than the plane of its body. It has a small crest of feathers at the back of its head. All these features make it easily recognizable. Two distinct colour morphs occur which could confuse a novice as being different species: the all-brown form and the pale morph which is almost completely creamy-white with darker streaks on the head and wings.

Wahlberg’s are conspicuous for their habit of perching in obvious places and because they soar over their territory regularly to hunt or to advertise their ownership through spectacular aerial cart-wheeling. They are also very vocal using a mournful whistled call during displays.

Tawny Eagle

©Karl Svendsen
Tawny Eagle (Aquila rapax)

The tawny eagle (Aquila rapax) is the commonest resident brown eagle and occurs in a variety of brown through blonde colours. It is larger than the Wahlberg’s with a shorter tail and is separated from other brown eagles by the fact that the gape only extends to the middle of the eye and never beyond. These birds are resourceful predators catching other birds in flight, pirating food from raptors or ground hornbills or scavenging it from carcasses or off vultures.

Martial Eagle

©Karl Svendsen
Martial Eagle (Polematus bellicosus) Addo Elephant NP, South Africa.

The martial eagle Polemaetus bellicosus, is a magnificent large eagle and a powerful hunter. It hunts on the wing spending hours of the day engaged in exploratory soaring covering areas extending 100-1000 km2. It can spot prey 6 km away and will drop upon it surreptitiously by making use of cover in its approach.

Martial eagles sometimes use ambush techniques when catching food perching secretly in a foliaged tree at a waterhole or over a well used game trail until opportunity presents itself. Although they specialize on eating monitor lizards and to a lesser degree other birds, martial eagles will take very large creatures including hares, rabbits, warthogs, ungulates up to the size of impala, baboons and other primates, jackals, caracal, polecat, hyrax, pangolin, mongoose and bats. They can lift eight kilograms although typically they only lift 1-4 kg. If prey is too heavy to lift to a perch, the martial will feed on it in situ for sometimes up to five successive days.

By Megan Emmet