Initial deadline for comments: 31 January 2012 [note that this has been moved back by about two months].
White-backed Vulture Gyps africanus and Rueppell’s Vulture Gyps rueppelli both have widespread ranges in sub-Saharan Africa, with G. rueppelli being more restricted to the north and east of this region, and G. africanus also ranging into southern Africa. Both species are listed as Near Threatened under criteria A2; A3; A4, on the basis that they are estimated or suspected to be undergoing moderately rapid population declines (20-29% over three generations, estimated to be 48 years in both species) owing to the threats of habitat loss, incidental poisoning, persecution, off-take for domestic and international trade, the loss of wild ungulates and possibly diclofenac poisoning.
Declines in G. africanus in West Africa have exceeded 90% (J.-M. Thiollay in litt. 2006), with declines also noted in Sudan (Nikolaus 2006) and Kenya (Virani in litt. 2006). Populations have apparently been stable in Tanzania (D. Peterson in litt. 2006) and in Ethiopia, according to Nikolaus (2006), although Ash and Atkins (2009) note anecdotal evidence that the species has declined there. The species is thought to have declined by c.10% in recent years in South Africa, Lesotho and Swaziland, although a range expansion was noted around Ladysmith in western KwaZulu-Natal in 2001-2002 (Hockey et al. 2005 and references therein).
Extremely rapid declines in West African populations of G. rueppelli have also been noted, although the species may be stable in The Gambia (J.-M. Thiollay in litt. 2006). During vehicle-based transect surveys in the Sahel zone of Mali and Niger by Thiollay (2006), G. rueppelli was not recorded, despite being common during equivalent surveys in the early 1970s, suggesting that the population has collapsed, although several incidental records are noted for Niger in 2004 and 2005. Significant declines also appear to have taken place elsewhere, including Sudan (Nikolaus 2006), Uganda (D. Pomeroy in litt. 2006), Kenya (M. Virani in litt. 2006) and Tanzania (J. Wolstencroft in litt. 2006). However, the species may be stable in Ethiopia (Nikolaus 2006).
A recent study involving the comparison of results from transect surveys conducted in and around Masai Mara National Reserve in 1976, 1988 and 2003-2005 lends support to the declines previously noted in Kenya (Virani et al. 2011). This study documented an apparent decline of c.52% over c.15 years in the numbers of Gyps vultures present during the ungulate migration season (Virani et al. 2011). In another study, carried out in central Kenya, an apparent decline of 69% was noted in the numbers of Gyps vultures between 2001 and 2003 (Ogada and Keesing 2010).
Assessing overall population trends in such widespread and mobile species is inherently problematic, and such species may also be prone to natural fluctuations in abundance. However, it remains necessary to evaluate whether the current listing of Near Threatened for G. africanus and G. rueppelli is likely to be correct. If evidence were to suggest an overall decline of at least 30% over 48 years in these species, then they may become eligible for uplisting to Vulnerable. Any evidence that strongly points towards a decline of at least 50% over 48 years would probably qualify them for uplisting to Endangered.
Further information is requested in order to assist with the assessment of these species’ threat status, with particular emphasis on their population trends.
Ash, J. and Atkins, J. (2009) Birds of Ethiopia and Eritrea: an atlas of distribution. London, UK: Christopher Helm.
Hockey, P. A. R., Dean, W. R. J. and Ryan, P. G. (2005) Roberts birds of southern Africa. 7th edition. Cape Town, South Africa: Trustees of the John Voelcker Bird Book Fund.
Nikolaus, G. (2006) Commentary: where have the African vultures gone? Vulture News 55: 65-67.
Ogada, D. L. and Keesing, F. (2010) Decline of raptors over a three-year period in Laikipia, central Kenya. J. Raptor Res. 44: 129-135.
Thiollay, J.-M. (2006) Severe decline of large birds in the Northern Sahel of West Africa: a long-term assessment. Bird Conserv. Int. 16: 353-365.
Virani, M. Z., Kendall, C., Njoroge, P. and Thomsett, S. (2011) Major declines in the abundance of vultures and other scavenging raptors in and around the Masai Mara ecosystem, Kenya. Biological Conservation 144: 746-752.