African Wildlife and Environment Issue 64

BIRDING

BIRDING

LIVING A DOUBLE LIFE

Birdwatchers can experience their first encounter with this magnificent ‘master of the African skies’ at either the Walter Sisulu Botanical Gardens, the Wonderboom in Pretoria or near the cable way on Cape Town’s Table Mountain where pairs have been breeding. These are the same birds that populate the remote granite hills of the Matobos, western Zimbabwe, and various other mountainous regions throughout South Africa. The Verreaux’s Eagle belongs to the Aquila genus of eagles. The Aquila eagles lay two eggs at the beginning of their breeding cycle. On hatching, the first laid egg hatches three to four days ahead of the second laid egg, so when the second egg hatches the first sibling is up to twice its size and immediately attacks the smaller chick. During this vigorous attack the larger chick continuously pecks the smaller on the head and back. This relentless sibling aggression is referred to as ‘Cainism’, after the sibling rivalry between Cain and Abel in biblical history. This attack results in the death of the second chick within 48 hours. It has been recorded that over 1 500 pecks take place during the attack sessions. In very rare occasions the adult female will feed the surviving chick on flesh taken from the dead chick. The dead carcass is not removed from the nest by the adults, andwill eventually disappear in the nest structure. There is no logical explanation for its aggressive behaviour; suggestions are that the second egg acts as a reserve in the event of the first egg not hatching. This magnificent eagle was named in honour of Jules Verreaux, the best known of three French brothers, who all visited southern Africa during the first half of the 19th century, collecting and mounting birds and other animals. The Verreaux’s Eagle was historically also known throughout Southern Africa as the Black Eagle. The Verreaux’s Eagle is the finest of the genus Aquila - a trulymagnificent coal blackbird. Thehandsomeplumage is enhanced by consummate grace in flight. It is easily recognised by the wholly black plumage, except for the narrow white V on the back of the perched bird. The plumage is identical in male and female. The eyebrow, cere and feet are rich yellow, the iris light brown with a yellow orbital ring, and the bill leaden horn with a black tip. In flight a striking Y-pattern of white is visible on the back, and there are white ‘windows‘ on the primaries visible from above and below. The flight outline is also diagnostic; the secondaries are shorter nearer the body, giving the wing a leaf shape. The tail is long and is usually held partially spread. Sexes are alike with the female the larger of the pair.

Willie Froneman

The wingspan of this soaring ‘machine‘ is 2.2 m. The male, being smaller, has greater manoeuvrability than the female, but her wider wingspan gives her more capacity for speed and height. When perched, the small head and tapering neck give this eagle an almost regal appearance. Mating usually takes place on a favourite rock perch near the nest, to the accompaniment of calling. The juvenile, unlike the adult, is cryptically coloured and its plumage blends with the broken rock, bush and trees of the surroundings. It has a handsome plumage, the most striking feature being the pale gold chestnut on the crown and mantle. The face is black with a mottled neck and breast, merging into buffish on the abdomen and legs. The juvenile lacks the white back pattern of the adults. The characteristic wing shape, as in the adult, prevents confusion with any other large raptor. The adult plumage is acquired between three and four years old. The species is distributed across five different biomes: Fynbos, grassland, Savannah, Nama-Karoo and succulent Karoo. They occur in rocky or mountainous terrain, but the environment may vary from semi-arid to areas of high rainfall. The distribution is closely linked to the presence of its principal prey, the Rock Hyrax Procavia capensis . Adults are resident, but juvenile and immature birds wander away from the areas in which they were reared. Their generally inaccessible habitat has not ensured an increase in their numbers. As man intrudes more and more, these magnificent eagles make for the inaccessible mountain peaks. They are locally distributed throughout southern Africa in suitable habitats, and absent from most of Botswana and Mozambique. They occur widely in the right environment as far north as the Sahara, extending through North East Africa into Egypt, Arabia and Israel, but rarely outside Africa. Paired birds may be seen in their territories year around. The pair bond is very strong and they fly, display, perch and roost together, and remain together for their lifetimes. However, should a bird lose a mate,

The Verreaux’s Eagle is found in two very contrasting and different worlds - in the remote out of the way, difficult to reach, mountainous areas, and then as urban-living eagles on the fringes of a city, ignoring the hustle and bustle of humans.

Photographs: Albert Froneman

50 | African Wildlife & Environment | 64 (2017)

51 | African Wildlife & Environment | 64 (2017)