The decline of raptors in West Africa: long‐term assessment and the role of protected areas

Abstract

Comparative large-scale roadside counts (8353 km), through Burkina Faso, Mali and Niger, conducted in 1969-73, were repeated 30-35 years later with the same observer and methodology and at the same season. The transect was divided into three geographical zones and between protected and unprotected areas. All diurnal raptors were recorded (22 801 individuals), as well as large game birds. Large vultures suffered a dramatic decline (98%) outside protected areas. The Hooded Vulture Necrosyrtes monachus population also collapsed in some regions, but survived in central Burkina Faso. Conversely, their abundance index did not decrease significantly in national parks. Four eagle species decreased by 86-93% and seven were not even recorded in the later study outside protected areas; by contrast, in national parks, only three species had declined marginally. Smaller Accipitridae (kites, goshawks, buzzards) also exhibited significant declines outside but not within national parks where woodland species reached their highest densities. The Common Kestrel Falco tinnunculus , mostly European migrants, declined sharply everywhere. African falcons decreased only outside protected areas. Among Palearctic migrants, Montagu's Circus pygargus and Pallid Harriers C. macrourus decreased significantly, Short-toed Eagle Circaetus gallicus less markedly, and Marsh Harrier Circus aeruginosus and Booted Eagle Hieraaetus pennatus not at all. Similar trends had previously been documented in Cameroon. They are associated with human population growth and development, global habitat degradation and ecosystem impoverishment (woodcutting, agricultural intensification, overgrazing, desertification). Heavy use of pesticides, control of locust outbreaks and overhunting have suppressed major food sources. Vultures may suffer from a shortage of carcasses, poisoning for predator control or persecution for trade of meat and body parts. Protected areas play a prominent role in the maintenance of vulture and eagle populations, even though they currently cover less than 2% of the Sudan zone and are virtually absent in the Sahel.

Large‐scale human effects on an arid African raptor community

“…These absences were unlikely due to sampling bias, because road transects have been successful in detecting large-bodied raptors in many other studies carried out in open systems such as our one (Don´azar et al, 1993;S´anchez-Zapata et al, 2003;Thiolay, 2006aThiolay, ,b, 2007Carrete et al, 2009). The increasing rarity of large vertebrates was also reported in other parts of the western Sahel (Mali, Burkina Faso and Niger), where the persistence of large raptors, ungulates and carnivores is restricted to a few protected areas (Thiollay, 2006a(Thiollay, ,b, 2007 and reflects the deep impoverishment suffered by biological communities in this area. As discussed below, this decline could be linked to the increasing density of human population.…”

“…In general, these species are undergoing long-term population declines (Sanderson et al, 2006) that may be related to environmental changes in the Sahel (Gordo et al, 2005;Grande et al, 2009). These changes also seem to affect resident raptors and some studies indicate that there is a close link between increments in human population size and the over-exploitation of resources and trends in raptor and other vertebrate populations (Thiollay, 2006a(Thiollay, , 2007.…”

Anthropogenic activities influence the abandonment of Bearded Vulture (Gypaetus barbatus) territories in southern Africa

“…Global vulture declines and declines in Bearded Vulture populations have largely been attributed to human impacts, namely human persecution for traditional medicine, food, ceremonies, and other purposes (Maphisa 1997, Xirouchakis et al 2001, Mander et al 2007, Thiollay 2007; indirect poisoning through poison baiting of carnivores (Brown 1991) and use of veterinary drugs , Oaks et al 2004; collisions with power lines (Krüger et al 2006); or a combination of these factors (Margalida et al 2008, Ogada et al 2012.…”

Realising the potential of herbarium records for conservation biology

“…While the possibility exists to obtain data from old field-based studies, re-visit the sites of these studies, and repeat the sampling procedures to compare current and historical biodiversity (e.g. Thiollay, 2006), such inventory data are often scarce and difficult to obtain, and "thinking-outside-the-box" methods are called for (Sparks, 2007). More specifically, biological collections, though often not systematically collected (see Supplementary Material 1), have the potential to provide a variety of information not only about individual species, but also about their communities and habitats (Sparks, 2007).…”