|Range:||se Botswana, e South Africa, n-c Namibia, Zimbabwe|
|Area of occupancy:||61,022 km2|
|Population estimate in Namibia:||8-11 ad, 2 imm 1 juv, 1 pr breeding suspected|
|Habitat:||High mountains, inselbergs, forages over open savanna|
|Threats:||Poisons, bush encroachment, drowning, electrocution|
Distribution and abundance
Click to see distribution map
This species is endemic to southern Africa occurring relatively commonly in two regions of South Africa: Limpopo Province and the Transkei/Eastern Cape. It is also concentrated in low mountains in s-e Botswana where it breeds in large colonies. Elsewhere it is rare, occurring in small satellite, breeding colonies in southern South Africa, and non-breeding colonies in Zimbabwe and Namibia (Brown 1985, Mundy et al. 1992, Mundy et al. 1997, Boshoff et al. 1997, Simmons & Bridgeford 1997, Anderson 2000, Borello & Borello 2002).
In Namibia it is thinly spread throughout central regions with concentrations only in the Waterberg Plateau Park where they once bred and in the Etosha National Park where they forage (Mundy et al. 1997). Satellite tagged birds moving 420 km in a day indicate that the Waterberg birds can forage over Etosha but rarely did so in the 2-9 months that five birds were followed for (Mendelsohn et al 2005). Historically, birds once occurred in the central Namib Desert where five colonies were known. In 1964 and 1969 Cape Vultures were common and occurred in a ratio of 1:2 and 1:4 with Lappet-faced Vulture (Sauer 1973); at Hotsas this represented about 25 birds in 1969. By 1985, poisoning and other factors had reduced the ratio of Cape to Lappet-faced to less than 1:100 and none of the colonies were active (Brown 1985). Almost all reporting rates from bird atlas data (Harrison et al. 1997) for Namibia remain low at less than 20% (Mundy et al. 1997). In its stronghold in the Waterberg mountains (the highest sheer cliffs on the nw side of the plateau), the bird's numbers have plummeted dramatically. In the 1940s local farmers estimated that about 500 birds occurred and bred on the Waterberg cliffs (Brown 1985). By 1970 about 300 remained followed by a precipitous crash to the early 1980s of about 10 birds. The decline was halted briefly with the establishment of a supplementary feeding scheme in August 1984 (Brown & Jones 1989) that provided 1-4 carcasses per month to draw birds away from poisons that were rife in the area. The population rose to 13 adult birds and breeding success increased from 0% in 1983 to 75% of 4 nests in 1984. By July 1991 up to 25 adult Cape Vultures were present at the carcasses (Berry 1997). Berry recorded 4 young in that year and five in 1992, 1993, 1994. Thereafter breeding suddenly stopped until, in 1997 only 3 adults and one immature remained (Berry 1997). Presently, with supplementary feeding still continuing under the eye of the recently formed REST (Rare and Endangered Species Trust), 8 - 11 ad, 2 imm and 1 juv ( hybrid Cape x White-backed Vulture) are presently associated with the Waterberg (M. Diekmann unpubl data). A helicopter survey of the escarpment cliffs in 2001 suggested that no breeding occurs but roosting was suspected (from fresh white-wash) despite an absence of birds (Simmons 2002). This has since been confirmed by two of the five birds satellite-tracked (Mendelsohn et al. 2005). The presence of young birds, however, indicates that pairs still breed and satellite tracking has revealed the first tree-nesting and some inter-breeding with White-backed Vultures (Diekmann unpubl data, Mendelsohn et al 2005).
The closest breeding colony to the Waterberg birds is in Botswana about 1000 km southeast (Borello & Borello 2002) indicating that the Namibian population, like the non-breeding Zimbabwe colony (Mundy et al. 1992) is a tiny outlier in a population centered in the southeastern subcontinent. Despite the isolation, young birds move hundreds of kilometres and the furthest movement on record was of a bird ringed in the former Transvaal and poisoned in central Namibia 1226 km west. Of 631 ringed birds, 6 South African birds have been recovered in Namibia (Oatley et al. 1998), indicating that genetic interchange can potentially take place even over large distances.
The global (southern African) population was estimated at 4400 pairs or about 12 000 birds (Piper 1994) contained within 84 breeding colonies. That number appears to have declined since 1994 to about 8000 mature individuals by the turn of the millennium (Anderson 2000).
Prefers open montane habitat, where strong winds promote soaring, and suitable cliffs provide breeding and roosting sites (Brown & Piper 1988). Small to very large breeding colonies have been recorded on steep fractured cliffs faces in Botswana, South Africa and Namibia (Mundy et al. 1982, Borello & Borello 2002, Brown & Cooper 1987, Brown & Jones 1989).
It forages over open grassland and open savanna woodland, generally from heights of 250 - 350 m but occasionally up to 1,000 m (Mendelsohn et al. 2005). It is excluded from closed (bush-encroached) woodland because of its high wing loading and apparent inability to take off once satiated from within dense tree cover. In Namibia five tagged birds spent most of their time foraging over commercial farmland and little time over communal lands or the protected areas of the Waterberg Plateau or Etosha (Mendelsohn et al. 2005). In South Africa, it is also found more often in farmland probably because of high stock losses, and also because vulture restaurants are providing carcasses regularly as part of conservation measures (Anderson 2000).
Searches for large carcasses of hoofed ungulates by soaring over suitable terrain and watching for other vultures descending onto carcasses (Mundy et al. 1992). Ranges at least 15 km from its roost, or over 700 km2 in the s. Cape (Boshoff et al. 1984), but much farther in Namibia. Satellite-tagged birds have recently shown that the home range of five Namibian birds varied from 11,800 km2 to 24,500 km2, similar in area to the entire Etosha NP (Mendelsohn et al. 2005). Wild ungulates have become limiting in South Africa as farmland and crops replace wildlands (Anderson 2000). In Namibia this is unlikely to be the case for the Waterberg birds given (i) the incidence of cattle farms in the vicinity (ii) the large and possibly increasing number of game farms in Namibia and (iii) increasing numbers of other vultures (Whitebacked and Lappet-faced) that occur at the Waterberg's Vulture Restaurant (Mundy & Simmons 1999).
A slow rate of recovery is guaranteed by the small clutch size (c/1), and the delayed maturation of this, the heaviest of southern Africa's vulture guild. In Namibia it breeds at the same time as other large vultures with a peak of egg-laying in June, with records also from May through August (Simmons & Bridgeford 1997). This is similar to Botswana but in both countries birds breed 1 month later than colonies in the former Transvaal (Mundy et al. 1997, Borello & Borello 2002).
The Cape Vulture's highly social nature makes it possible that once the small satellite colonies present in Zimbabwe and Namibia reach a threshold below about 20 adult birds they may stop breeding and move elsewhere, possibly as a unit of known individuals (Vernon 1997). This appears to have happened at both the Waterberg and Zimbabwe colonies (Mundy & Simmons 1999). Alternatively birds that stay may begin to hybridize with White-backed Vultures as suspected in two cases at the Waterberg colony (M Diekmann unpubl).
The main threats to the Cape Vulture's continued existence in Namibia is a combination of poisoning and the severe bush encroachment that has occurred in the last 100 years around the bird's last breeding site at the Waterberg (Brown 1985, Simmons & Bridgeford 1997, Mundy & Simmons 1999). Poisonings have been recorded throughout Namibia including immediately around the Waterberg Plateau breeding area when 22 Lappet-faced and/or Whitebacked Vultures were poisoned on a farm nearby, 19 of which were rehabilitated (T. Cooper in Bridgeford 2001). A total of 226 vultures of 3 species died unnaturally in the 6 yr period between 1995 and 2001, 87% of which were poisoned (Bridgeford 2001, 2002). At a minimum average of 38 vultures killed per year, it is no wonder that many of Namibia's vultures are declining. A few farmers are typically responsible for most of these deaths (Brown 1991, Simmons 1995), although some are probably deliberately killed for the traditional medicine (muti) trade (below). Little direct evidence exists for Cape Vultures as victims except that the Waterberg birds suddenly stopped breeding after 1994 when the population dropped from 25 birds to 3 adults and 1 immature (Berry 1997).
Muti trade in vulture parts is known from South Africa and Lesotho (Cunningham 1990, Beilis 1999) but until recently it was not known from Namibia. A recent report indicates that of 17 traditional healers 47% used vulture brain in their trade, 41% used feathers and 6% used the liver. From the same sample from Windhoek and Okakarara, 29% said they obtained parts from dead vultures, another 29% said they obtained parts from killing vultures, while 3% said they obtained parts from pharmacies or acquaintances. Only one healer claimed he used Cape Vultures (now doubted: M Diekmann pers comm.), and all indicated that vulture nestling were preferred (Hengari 2002, Hengari et al. 2004). The continued vulture poisoning around the Waterberg Plateau close to the town of Okakarara (Simmons & Bridgeford, Bridgeford 2001, 2002) can thus be explained (and probably solved - below). Given that 1500 traditional healers have applied to register with Namibia's Ministry of Health and Social Services (Barlow in Hengari et al. 2004) means that the threat could be very much greater than suggested here.
Other threats include drowning in farm reservoirs which in South Africa claim more Cape Vultures than any other species of raptor (120 birds in 21 known incidents: Anderson et al. 2002). This may be related to their highly developed social behaviour for foraging and breeding. Two Cape Vultures were removed (alive) from the canal of the Eastern National Water Carrier near the Waterberg, when it was first constructed, but none were subsequently found in several years of weekly to monthly monitoring (Anon 1992).
The commonest mortality factor of Cape Vultures ringed and recovered in South Africa was electrocution (54 birds: Oatley et al. 1998), but there have been no reports from Namibia, but local NGOs are in discussions with Nampower to assist pylon design.
Future threats that can now be discounted are the mortality factor decimating an estimated 100,000 Gyps vultures in India and Pakistan (Anderson & Mundy 2001). This is now known to be caused by Diclofenac used by veterinarians to cure cattle of arthritis, causing kidney failure in vultures when they consume treated cows (Oaks et al. 2004). Some diclofenac is used in southern Africa but the risk of threat is unknown but probably low.
Cape Vultures are classified as Critically Endangered because of a 96% decline from about 500 birds in 1940s to about 11 birds present day; known breeding colonies have also declined from five formerly in the Namib Desert to the one extant colony associated with the Waterberg Plateau Park. It is classified as Vulnerable in South Africa, given its larger, healthier populations. However there too, roosting and breeding sites have decreased during the 20th century from 441 to 167 sites, with a suspected 20% decline in numbers in the last 3 generations (Anderson 2000). It is also classed as Vulnerable in the global Red list due to continuing rapid decline in southern Africa where it is endemic (Stattersfield & Capper 2000, Birdlife International 2004).
Lacing carcasses with poisons for the control of carnivores such as jackal has recently been banned in the draft Parks and Wildlife Management Bill of the Ministry of Environment & Tourism. Farmers may, however, apply for permits to control particular animals. This should be rigorously enforced.
Continuing the supplementary feeding scheme at the Waterberg Plateau Park or the nearby REST headquarters should remain a priority, as well as continuing education on the responsible use of poisons. This is being undertaken in the form of explanatory booklets and posters on vultures and predators, as well as and talks to farming communities by organizations such as the Vulture Study Group (P. Bridgeford), NARREC (L. Komen) and REST (M. Diekmann). This includes newspaper articles in several languages which are reaching a much wider audience of the Namibian public. This should continue and include the targeting of traditional medicinal healers in former Hereroland near the Waterberg Park.
Bush clearing programmes, funded through USAID and undertaken by the Cheetah Conservation Fund in the Waterberg area should be promoted for the conservation of both the cheetah and Cape Vulture over a wider area. Providing vulture parts from the captive breeding and release programmes of Cape Vultures (REST) or rehabilitation centres (NARREC) to recognised traditional healers, should be considered. This should be carried out with a guarantee that feathers or other parts will be provided only to healers who do not obtain parts from the killing of wild vultures.
All farm reservoirs, but particularly those in the vicinity of the Waterberg Park should either be covered or provided with ladders enabling trapped birds to escape (Anderson et al. 2002).
An ambitious programme to reintroduce rehabilitated Cape Vultures from South Africa currently (2006) has 18 birds for release below the Waterberg's cliffs spearheaded by REST (Brand 2002, Diekmann 2005). Funding has allowed satellite collars to be fitted to the remaining wild birds to understand their foraging patterns (Diekmann 2005, Mendelsohn et al. 2005).
The fact that the Cape Vulture colony at the Waterberg colony lies outside the Waterberg Plateau boundary is not seen as a problem, given that the Waterberg conservancy surrounds the plateau.
A recent move by some vulture biologists to re-name the large Gyps Vultures, "Griffon" Vultures is based on the idea that they are "super vultures" usually large, pale-eyed, cliff-nesting species, that typically follow large herds of ungulates for their food source (Mundy 2002). Since this splitting is not supported by the best molecular data available (Wink 1995, Seibold & Helbig 1995), and is causing confusion with the existing Griffon Vulture from Europe (Clark 2002), we, nor the new Roberts (Hockey et al. 2005) follow, nor recommend this nomenclature here.
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