diagnostics
1.0-1.2 m, 7.3-10.9 kg. Sexes alike in appearance, but female slightly larger. Head and neck bluish, bordered by ruff of fluffy white feathers. Crop patch with dark brown feathers and twin, bare blue patches on breast. Body feathers off-white, creamy or russet. Scapulars and tertials brown, edged white. Tail blackish brown. Remiges dark; undersides of secondaries paler and tipped black. Upperwing coverts whitish; greater coverts with large central black patch. Underwing coverts whitish; sometimes with row of sub-terminal black spots on greater underwing coverts. Bill and cere black. Eye straw-yellow. Legs and feet black. Immatures gradually transition to adult plumage over about six years. Juveniles are darker, with woolly down on head, and bare pinkish skin on hindneck, and red patches on breast, and streaked underparts; eyes initially black, becoming yellow in fifth or sixth year.
Readily confused with White-backed Vulture G. africanus, especially when seen in flight and over distance. Adult Cape Vultures are differentiated from White-backed Vultures by their larger size, straw-coloured eyes, and blue colour to the exposed skin on the head, neck and breast patches. Seen in flight from below, the adult has pale, silvery secondaries that contrast poorly with the equally pale underwing coverts. Adults (and older immatures) often show a line of distinct dark spots along the greater upperwing coverts, and along both the greater underwing coverts and greater under primary coverts, in both cases most conspicuous when seen in flight from above and below. The more streaked juvenile and immature Cape Vultures differ primarily from young White-backed Vultures in the reddish colour to the exposed skin of the head, neck and breast patches, which are black in all age classes of the latter species. They are also never as dark and heavily streaked as juvenile White-backed Vultures. In flight, young Cape Vultures lack the striking pale lines typically present in the underwing coverts of young White-backed Vultures (Mundy et al. 1992, Ferguson-Lees and Christie 2001).
trophic
The breeding biology of the Cape Vulture is fairly well known (Mundy et al. 1992, Piper 2005, Tarboton 2011). The age of first breeding is six years, rarely 4-5 years with an estimated 80-93% of pairs breeding annually (see Benson (1997) for confirmation that some marked adults do not breed annually). Cape Vultures nest on tall cliff faces, typically in fairly large and discrete colonies numbering up to 1 000 pairs (Benson et al. 1990). The species is monogamous.
Egg-laying spans March-September, mainly April-July, with a May-June peak with the timing of breeding appearing to synchronise the period of highest food demand (the middle third of the nestling period) with the period of highest food availability (Komen and Brown 1993). The clutch almost invariably comprises a single egg, only very rarely are two eggs recorded (less than 1% of instances and possibly involving two females). The combined incubation and nestling periods cover some 6-7 months and an entire successful breeding attempt from nest building to the final independence of the fledgling can take up to almost a full calendar year.
Breeding success (fledglings or large nestlings produced per egg laid) is 45-78% (mean=60%) (Mundy et al. 1992); at Kransberg breeding success (fledglings produced per occupied site) spanned 37-61% (mean 50%) per year (Benson 2000). The generation time of the species is unknown but has been estimated at 16 years (BirdLife International 2014).
The Cape Vulture seems to have foraged, at least ancestrally, across all of the characteristically more open vegetation types, i.e. Fynbos, Karoo, Kalahari, grassland and open woodland (Mundy 1983, Mundy et al. 1992, Mundy et al. 1997). It is essentially excluded from forest and dense woodland likely due to difficulties in locating and accessing suitable carcasses in such habitat (Schultz 2007).
Gyps vultures are unique among extant vertebrates in being obligate scavengers (Ruxton and Houston 2004, Dermody et al. 2011, Ogada et al. 2012). They feed, typically in large groups, on large mammalian carcasses, both wild and domestic, favouring the soft internal organs and muscle tissue (Mundy et al. 1992, Piper 2005). These vultures typically search for food communally, fanning out to search for carcasses on the wing and responding to cues from one another (Houston 1974). Recent research has emphasised the important ecological role played by these birds in carcass removal, e.g. related to disease control (Ogada et al. 2012).
