White-Headed Vulture
Trigonoceps occipitalis
Status: Vulnerable
Range:Botswana, n Namibia, ne South Africa, Zimbabwe
Area of occupancy:78,477 km2
Population estimate in Namibia:< 1,000 birds
Population trend:Has declined
Habitat:Mixed woodland savanna
Threats:Poisons, decline in prey abundance

Distribution and abundance


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Widespread in sub Saharan Africa's woodland savannas, but nowhere is it abundant (Mundy 1997b). Its southern African population was estimated at about 500 prs (Mundy 1997b) and the African population is estimated at 7,000 - 12,500 mature individuals (Mundy et al. 1992). South African breeding populations number about 80-120 prs (Anderson 2000). Its core areas are the Kruger NP, the regions surrounding the Zambezi River in Zimbabwe, and large parts of Botswana. In Namibia it is found primarily within Etosha NP and throughout the Caprivi Strip, with a small pocket of birds apparent in the Kavango woodlands n of Bushmanland (Mundy 1997). There is no estimate of the Namibian population size (Simmons & Bridgeford 1997), but raptor road counts in the Etosha and Caprivi region indicated from 0.1 birds/1,000 km to 7.2 birds/1,000 km driven (Jarvis et al. 2001), fourfold higher than the Rare Hooded Vulture. Given that reporting rates were also (x2) higher than Hooded Vultures, this species is probably twice as abundant as the Hooded and populations thus number about 1,000 birds. This is 10% of the estimated global population (Mundy et al. 1992), but this needs confirmation.

Ecology

Prefers the mixed broad-leaf tropical woodlands of southern Africa, particularly those occurring in Kalahari sands in Botswana. In Namibia, this explains its presence in Caprivi and Bushmanland, but it is also found in the arid thornveld areas where potential prey populations are intact such as w Etosha NP (Mundy 1997).

Feeds by scavenging from both large and small carcasses but like the Bateleur it is skilled at finding smaller carcasses (Steyn 1982, Mundy et al. 1992). It is also thought to directly kill small mammals (Steyn 1982, Mundy et al. 1992) and procures some prey by pirating it from other species (Mundy et al. 1992).

Breeds mainly in the winter in southern Africa (Mundy et al. 1992). Breeding records from Namibia are rare with the only (3) records coming from June (2) and July (1) (Brown & Clinning unpubl data, Jarvis et al. 2001). A single young was recorded from one of these nests (Jarvis et al. 2001) as is typical for this species (Mundy et al. 1992).

Threats

Like other vultures this species almost certainly suffered from poisoning, even though few poisoned birds have been found (Anderson 2000). However, in the 7 yr period 1995-2001, 2 birds were found poisoned in the Mangetti, 50 km east of Etosha NP together with 4 African White- backed Vultures (Bridgeford & Simmons unpubl data). This comprises 2 of 147 other vultures known to be poisoned in this period, at a rate of 21 known poisoning per year. Given it similar foraging methods to the Bateleur (Steyn 1982), it may be very prone to small poison baits because it is rarely reported from the larger poison incidents which are still common in Namibia (Brown 1988, Simmons 1995, Bridgeford 2001, 2002). Further evidence for poisoning is based on the complete lack of birds in Namibia adjacent to areas such as the Kgalagadi Transfrontier Park (South Africa/Botswana) where they are relatively common (Mundy 1997), their absence from small-stock farming areas in southern Namibia where poisoning of small carnivores is common (Brown 1988), and their confinement in n Namibia to the Etosha NP or areas where small-stock farming does not occur. Breeding birds are especially prone to nest desertion (Steyn 1982), and this may eliminate it from breeding in any areas where human disturbance is high.

Conservation status

This species is classified as Vulnerable because its population in Namibia is suspected to have declined by 10% in the last three generations based on the high incidence of poisoning in Namibia which claims a minimum of 21 vultures per year (Simmons & Bridgeford unpubl data). Its absence immediately outside conservation areas such as Etosha NP, and suitable regions between there and the Kavango woodlands to the east suggest that poisons are the main source of mortalities. Trampling and over-grazing in range lands may reduce the small mammal populations on which it feeds (Mundy 1997), and this too may explain its absence from areas where poisons are used less often in cattle-lands.

It is not classified as globally threatened because of its wide distribution throughout Africa (BirdLife International 2004). In South Africa it is classified as Vulnerable based on a suspected 10% decline (Anderson 2000), probably also as a result of poisoning associated with problem animal control operations and the acquisition of birds for traditional medicines.

Actions

Decreasing the incidence of poisoning is paramount in preventing further population declines in all species of vultures. There are several ways of doing so which are discussed under Lappet-faced Vulture. Briefly, 1080-filled poison collars have proven unsuccessful in preventing poisoning of non-target species (Gildenhuys & Brown 1991). Second, a complete ban on poisons used for killing small carnivores in Namibian is advocated by Brown (2002). He argues that despite farmer-directed awareness campaigns, educational posters and environmental education programmes, poisonings continue to kill Namibia's vultures and other scavenging raptors. The critical point is that 100% of farmers need to be convinced of the need for sound farming and poison-free methods. For this reason awareness campaigns alone may never work. The opposite view is that the total ban is (i) impractical (ii) threatens the agro-chemical industry and (iii) is too idealistic to work (Verdoorn & Komen 2002). Concentrating on stopping abuse and working with farmers is seen as the only way forward. The draft Parks & Wildlife Management Bill (2002) has now banned the use of poisons in predator control, and permits are required from the Ministry of Environment & Tourism for farmers to use poisons in exceptional cases. While the Egyptian and Cape Vultures are Specially Protected Species under this Bill (requiring management plans and annual updates), the White-headed is not. It will, however, remain protected under the same legislation.

This vulture requires monitoring of breeding pairs and its occurrence at vulture restaurants. Any reports of poisoning of this species like all other vultures should be followed up, publicized and appropriate actions (prosecution and education) taken.

From: Simmons RE & Brown CJ 2006. Birds to watch in Namibia: red, rare and endemic species. National Biodiversity Programme, Windhoek, Namibia

References

Anderson MD 2000. White-headed Vulture In Barnes KN (ed) The Eskom Red data book of birds of South Africa, Lesotho and Swaziland. Birdlife South Africa, Johannesburg.

Barnes KN (ed) 2000.The Eskom Red data book of birds of South Africa, Lesotho and Swaziland. Birdlife South Africa, Johannesburg.

Birdlife International 2004 Threatened Birds of the World. CD Birdlife International, Cambridge.

Bridgeford P 2001 More vulture deaths in Namibia. Vulture News 44: 22-26.

Bridgeford P 2002 Recent vulture mortalities in Namibia. Vulture News 46:38.

Bridgeford P, Simmons RE unpublished data. Recent unnatural vulture deaths in Namibia.

Brown CJ 1988 Scavenging raptors on farms: what is their future? African Wildlife 42: 103-105.

Brown CJ 2002 Poisons and scavengers - the right way forward! Lanioturdus 35: 3-6.

Gildenhuys SD Brown CJ 1991 Field trials on poison collars for mammalian predators in Namibia: their effects on birds of prey Gabar 6: 10-12.

Jarvis A Robertson AJ Brown CJ & Simmons RE 2001. Namibian Avifaunal Database. National Biodiversity Programme, Ministry of Environment & Tourism, Windhoek.

Mundy PJ, Butchart D, Ledger J, Piper SE 1992. The Vultures of Africa. Acorn and Russel Friedman Books, Halfway House, RSA.

Mundy PJ 1997. Whiteheaded Vulture. In: Harrison JA, Allan DG, Underhill LG, Herremans M, Tree AJ, Parker V, Brown CJ (eds). The Atlas of Southern African Birds Vol 1: 164-165. BirdLife South Africa, Johannesburg

Simmons RE 1995. Mass poisoning of Lappetfaced Vultures in the Namib Desert. J African Raptor Biology 10:3.

Simmons RE, Bridgeford P 1997. The status and conservation of vultures in Namibia. In: Boshoff AF Anderson MD & Borello WD (eds.). Vultures in the 21st Century. Pp 67-75 Vulture Study Group, Johannesburg.

Steyn P 1982 Birds of prey of southern Africa. David Phillip, Cape Town.

Verdoorn G & Komen L 2002 Counterpoint from the Poison Working Group. Lanioturdus 35: 7-11.

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