African Wildlife and Environment Issue 66

BIRDING

BIRDING

bulky platform of sticks, twigs and dried grass worked into a firmmass, with a shallow cup lined with grass. Old nests are often re-furbished. Most clutches are nearly always a single egg, laid during May. The egg is off white, occasionally with pale rufous or purple blotches. The incubation period is 57 days, the female and male share the incubation equally on a roughly day-on, day off basis. The off-day is spent on foraging for food. The egg takes two days to hatch. The nestling period is from 140 to 145 days. For the first 70 days young are fed bill to bill, the returning parent bird brings the ‘baby food’ which is a crop full of foul-smelling, decomposing flesh. The baby food is regurgitated and fed to the chick. Bone fragments are regularly fed to meet important calcium requirements. After the first 70 days the returning bird merely regurgitates the food on the nest for the young to self feed. At 100 days with a mass of eight kg, the young bird is able to stand on the nest exercising its wings. After the first flight, at about 140 days, the nestlings return to their nest for roosting. The post-nestling dependence is about another 100 days. Young are driven away by start of following egg-laying season. These young birds often wander up to 750 km from colony site. Cape Vultures are meticulously clean birds, and therefore they wash after every meal. They bathe by dunking their heads and necks into water and tossing water over their backs with their wings. After bathing, a bird stands with its wings held open facing into a breeze. They may also lie down on the ground in a spread eagled fashion. Preening, which is an important part of their behaviour is then performed Outside the breeding season the Cape Vulture generally roosts for the night on cliffs, which then become whitened and conspicuous. However they will use trees when the occasion demands. Since the late 1960s they have taken to roosting on electricity towers or pylons. However, this behaviour can have fatal consequences. Cape Vultures are globally vulnerable. The suffer mortality by poisoning, electrocution on certain types of electric pylon or poles, and many break their wings by colliding with overhead powerlines. Vulture carcases are also used in traditional medicine, and many birds may be poisoned for this purpose. There are also mass poisonings, apparently by poachers who fear the vultures will alert the authorities to their nefarious activities. All these factors are diminishing the Cape Vulture population quite dramatically.

birds nearly all the time, seldom seen singly. There are breeding sites on the south-facing Magaliesberg, on the border of the bushveld to the north. During December 2016 about 300 gathered at carcases placed out at the Nyoka ridge ‘vulture restaurant’ in the Skeerpoort region of the Magaliesberg. More breeding sites are concentrated on and around the Drakensberg massif and escarpment of Lesotho and KwaZulu Natal. They make their nesting sites on the escarpments, and in river gorges. There is a breeding site on an isolated sandstone mesa called Aasvoelberg near Zastron. There are several sites in the Eastern Cape on the cliffs of the Mzikaba River with some nests only two km from the Indian Ocean. Adult birds sighted in the Kruger National Park, as they often are, probably come from theManoutsa colony on the Limpopo Drakensberg, 75-125 km to the west of the middle of Kruger. They are colonial breeders, the same pair using the same cliffs, year after year. The nest is built by the female with most material brought by the male. The nest is a

species, and he depicted it very well in a pose similar to that of the specimen mounted in the ‘ Rijksmuseum van NatuurlijkeHistorie ’ at Leiden in Holland. The specimen is still there, it is an immature bird with a feathery ruff. It appears that in 1799 a German by the name of Johann Reinhold Forster, translated Levaillant’s story of his exploration in southern Africa, and named the Cape Vulture Vultur Coprotheres for the very first time. Early in the 20th century Charles Richmond made a correction and the bird became Gyps coprotheres , this 200 years after the species was made known to the world. It is not difficult to identify the cliff-sites used for roosting and nesting. The ‘whitewash’ gives these away from a distance. Their dependence on suitable nesting sites means that breeding Cape Vultures are restricted regionally to cliffs. It is the only extant vulture in southern Africa to nest colonially on cliffs, and it is this habit that gives rise to its Afrikaans name ‘Kransaasvoel’. Not all cliffs provide suitable nesting sites. Granite and dolomite cliffs seldom have the shelves and ledges the birds need for nesting. On the other hand sandstone and quartzite formations have numerous ledges, which are good sites that are inaccessible to potential predators. These ledges that are in use have probably been occupied by Cape Vultures for many generations and perhaps even for thousands of years. Their distribution is widespread in South Africa where suitable cliffs are present in mountains, also in adjacent countries. About 80 sites are used as breeding colonies, the largest being at Groothoek (also called Kransberg) in the west-central Limpopo province. They are gregarious

of long and lanceolate feathers of a buffy hue which cascade around the base of the neck. The naked ‘eye’ patches on either side of the crop, have the same skin colour as the neck. The contour feathers are streaked and generally browner in colour, most obvious on the underbody. The head and face of the juvenile have a ‘babyish’ appearance in contrast to the adult’s stern look, owing to the lesser development of the orbital ridge over the eye. At the age of six the young bird is in full adult attire. In both the adult and juvenile birds, the sexes are alike, with the female being the slightly bigger bird. The Cape Vulture is near endemic to southern Africa. History tells us that they were on Table Mountain two to three centuries ago. They did indeed occur at the Cape of Good Hope, where they would have sailed in the constant winds around Table Mountain itself. Jan van Riebeeck arrived in April 1652, and soon ‘Kaapstad’ developed. During those early years vultures were referred to as ‘dreck-vogel’ by the Dutch. It seems that Johann Schreyer was the first person to mention ‘ dreck-vogel’ in the seventeenth century – he arrived in December 1668. In April 1781, the Frenchman Francois Levaillant arrived at Cape Town and stayed for little over three years. Levaillant was the first traveller to the Cape to make a specific and detailed study of the bird life. He saw Cape Vultures at Table Mountain nearby, and reported that they were numerous, and fed on dead creatures, where they gathered in numbers of a hundred upwards. He wrote very knowledgably about this

Willie Froneman Birding Expert & Enthuisiast willie.froneman@gmail.com

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61 | African Wildlife & Environment | 66 (2017)