BirdLife species factsheets for Arabian Bustard and Nubian Bustard Arabian Bustard Ardeotis arabs and Nubian Bustard Neotis nuba are found from the Sahel zone of West Africa, with Nubian occurring marginally in the Saharan zone, and both species range east through Chad and Sudan, with Arabian Bustard also ranging into Eritrea, Djibouti, Ethiopia and to the south-western Arabian Peninsula. N. nuba is listed as Near Threatened under criteria A2c,d; A3c,d; A4c,d on the basis that it is suspected to be undergoing a moderately rapid decline, estimated at 20-29% over 10 years, owing to intense hunting pressure in parts of its range, among other potential threats. BirdLife estimates the generation length for this species to be c.10.3 years, thus the rate of decline should now be estimated for a three-generation trend period of 31 years. A. arabs is listed as Least Concern on the basis that it was not thought to approach the thresholds for Vulnerable under any of the IUCN criteria. This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence of less than 20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (at least a 30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (fewer than 10,000 mature individuals with a continuing decline estimated to be at least 10% over ten years or three generations, or with a specified population structure). Survey results and anecdotal observations from the more accessible and better monitored parts of the range of A. arabs suggest that this species has undergone a rapid decline in recent decades owing to habitat destruction and hunting (del Hoyo et al. 1996, Thiollay 2006). Vehicle-based transect surveys for raptors in the Sahel zone of Mali and Niger in 2004 failed to record any bustard species, despite both A. arabs and N. nuba being frequently recorded along the same transects in 1971 and 1973 (Thiollay 2006). Bustards can be inconspicuous, which, coupled with the focus of these surveys on raptors, means that some birds were probably missed, and local hunters reported that bustard species were still extant in the surveyed areas; however, the difference between the survey results from the early 1970s and 2004 most likely indicates dramatic declines in these species (Thiollay 2006). Despite the Sahel zone seeing only a limited impact from West Africa’s rapid human population growth, along with low population densities and a predominantly traditional nomadic lifestyle, habitat degradation is occurring through the thinning of sparse non-regenerating Acacia woodlands, as well as the over-grazing of sub-desert steppes and excessive harvesting of firewood, which are followed by wind erosion and sand encroachment. However, overhunting is probably the main cause of declines in the bustard species of Sahelian West Africa. Off-take by local nomads has been augmented by the hunting activities of military and mining personnel and tourists (del Hoyo et al. 1996, Thiollay 2006). The population of A. arabs on the Arabian Peninsula is very small and likely to be in decline owing to hunting, habitat loss and the effects of pesticides (del Hoyo et al. 1996). The species is reportedly still fairly common in parts of western Yemen; however, the intensification of agriculture may pose a threat (del Hoyo et al. 1996). Additional information on these species is requested, in particular on the severity of threats and likely population trends throughout their ranges. Any evidence of a decline approaching 30% (typically 20-29%) over the last three generations, estimated by BirdLife to be c.47 years (one generation = c.15.6 years), would probably qualify A. arabs for uplisting to Near Threatened under criterion A. If the rates of decline in either species were suspected to be at least 30% over three generations (c.31 years for N. nuba; BirdLife International unpubl. data) they would be eligible for listing as Vulnerable, and a suspected decline of at least 50% over three generations would qualify them as Endangered. The threshold for Critically Endangered is a decline of at least 80% over three generations. References: del Hoyo, J., Elliott, A. and Sargatal, J. (1996) Handbook of the birds of the world, Vol 3: Hoatzin to Auks. Barcelona, Spain: Lynx Edicions. 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.
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