African Wildlife and Environment Issue 66

BIRDING

BIRDING

from the cold ground below. Occasionally a dust-devil on the ground, hundreds of metres below, will grow into a full-blown thermal, sweeping leaves high up into the air, signalling to the vultures that there is a free lift on offer. The airspace is suddenly filled with vultures peeling off the cliffs and spiralling upwards. In general during warmer climates most birds do not actually get away until eight o’clock in the morning. No doubt each colony or roost produces its own flight patterns in the resident vultures, according to the prevailing climate. Once airborne, they congregate in the thermals. No Cape Vulture seems able to resist a thermal, and should a pioneering bird find one and start circling, nearly all other birds in sight will head for the spot. As thermals are ‘bubbles’ of rising air, they can quickly take soaring birds to high altitudes. A curious but highly distinctive behaviour pattern by Cape Vultures is formation flying, appropriately called ‘tandems’ for two birds and ‘stacks’ for three or more. These flights occur very often at the colonies. Also at a cliff-site, tandems and stacks are mainly seen when birds return from foraging. It may be that tandems/stacks require slope-lift (orographic winds) for their performance, and that cannot be done over the plains. There is no clear-cut explanation for the ‘tandem’ flying behaviour; perhaps it is simply a pleasant sensation the bird gets riding in another’s slipstream! The Cape Vulture has aroused great respect and wonder by the way in which the birds can gather in numbers at a dead beast so quickly and so synchronously. It has also attracted the most conservation attention of any vulture in Africa, and possibly of any in the Old World. The adult Cape Vulture’s head is covered in white hairy feathers, the facial skin has a hint of blue, the iris is a straw-yellow, and the bill and cere (skin on the nose and eyes) are black. The face is dominated by the strong orbital or eyebrow ridge which gives the adult a very fierce appearance. On either side of the crop is a round bluish skin patch, which sometimes as the face, becomes reddened, presumably during excitement of one sort or another. A diagnostic and conspicuous feature for the species is the central black patch in the row of feathers of the contours on the creamy white upper wing feathers. The primary flight feathers and tail are blackish; the undersides of the secondaries are white with a narrow black tip, as well as a row of black spots. From above in flight, the black bastard-wing or alula stands out against the white wing, which in the birding world is referred to as landing lights. Finally the feet are black, the inside of the legs are clothed with downy feathers, while the outsides are covered in long contours. The juvenile is very different in colour and pattern. Its eye is black, the skin of the neck is coloured pink to magenta, and the head is covered in white woolly down. The ‘wool’ seems to accentuate the naked skin at the rear base of the neck. The naked eye patches have the same skin colour as the neck. The ruff is composed

It is an exhilarating experience to sit quietly above a breeding colony of Cape Vultures ( Gyps coprotheres ). Far below, andmostly out of sight from the top, innumerable vulture parents sit on their nests. Throughout the day vultures fly about in front of the cliff, and every now and again a bird will sail past, so close that one can easily discern its beady yellow eye, set in a woolly grey head. The Cape Vulture is a very large bird, and marvellous to behold in flight as it glides and circles in the air, with its primaries fingering the up-draughts and its wings extracting the maximum possible lift for its heavy body of close to 9.5 kg. Being such a heavy bird, the Cape Vulture needs considerable air movement in order to fly. At cliff sites, birds wait for sufficient thermals to develop

The majestic CAPE VULTURE

Willie Froneman

Watching a Cape Vulture, with a wingspan of 2.5 metres, gliding past effortlessly, makes you realise how breathtakingly magnificent this majestic bird really is. Sitting on top of a mountain range where the Cape Vultures roost, waiting for them to return in the late afternoon, is an awesome experience. The arrival of the first stack (three or four birds flying in a formation) returning from their continuous search for food, make these birds incomparable to many other species. Watching them glide effortlessly past, drives home the magnificence of these majestic birds.

Photographs: Albert Froneman

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59 | African Wildlife & Environment | 66 (2017)