The feeding ecology of cape vultures Gyps coprotheres in a stock-farming area
ABSTRACT Cape vultures Gyps coprotheres in the southwestern Cape Province feed exclusively on sheep carcasses, within a limited foraging area. The size and shape of the foraging range was determined by means of a postal survey and confirmed by a radio-tracking study. The quantity of food available within the range, while seasonally variable, was estimated to exceed the colony's requirements. Data pertaining to daily feeding forays of individuals, monthly foraging patterns of the colony and the growth of nestlings indicated no seasonal shortages in the amount of food obtained. The colony remains susceptible to the effects of poisons used in the area; levels of contaminants recorded in most eggs are considered low.
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ABSTRACT: Capsule Young Griffon Vultures Gyps fulvus suffer intense competition from elders at feeding sites and this reduces their intake rate.Aims To explore the costs and benefits of feeding in groups in Griffon VulturesMethods In a French population of individually marked vultures, we studied by video the dynamics of feeding events and the difference in competitive ability to access carrion between ages and sexes.Results When several carcasses were available, the distribution of the birds at the beginning of feeding event was generally different from an ideal free distribution. Depending on food availability, the potential group size was always higher than the maximum group size observed. However, the number of birds landed increased with food mass and was always higher than the potential group size, in accordance with the stable group size hypothesis. The timing of arrivals and departures of individuals differed with respect to their age, with old adults arriving and leaving before the arrival of other age-classes. Some birds, mostly old adults with a lower interaction rate, aggressiveness and dominance, regularly started the feeding events first.Conclusions At high-intensity feeding sites close to the colonies younger vultures probably access a lower quantity and quality of resources than old adults.Bird Study 01/2012; 59:182-192. · 1.02 Impact Factor
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ABSTRACT: South Africa is home to 9 vulture species, of which 7 are endangered. While the cause of the population declines remains largely speculative, a vast amount of effort has been dedicated towards the protection of populations by ensuring sustainable and safe food sources for the various colonies. Limited focus was placed in the past on efforts related to the rescue and/or rehabilitation (R&R) of injured birds and the release of these birds back into the wild. This paper provides an overview of the causes, the impact and success of 3 organisations involved in R&R efforts of vultures in the Magaliesberg mountain range and surrounding areas over a period of 10 years. Study material included 162 Cape griffon (CGV) and 38 African white-backed (AWBV) vultures. Datasets include the number, sex and age of birds received, the reason the vultures were brought in for R&R, surgical interventions performed and outcomes of rescue efforts. The CGV dominated the rehabilitation attempts. Results further show that a large number of apparently healthy birds were presented for veterinary treatment. The R&R data clearly indicate that the major cause of injuries was birds colliding with overhead pylons, as a high number of soft tissue and skeletal injuries were observed. The study also shows that successful releases of rescued birds are possible. It is concluded that urbanisation has had a major negative impact on vultures around the Magaliesberg mountain range.Journal of the South African Veterinary Association 03/2011; 82(1):24-31.
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ABSTRACT: Vultures in the Gyps genus are declining globally. Multiple threats related to human activity have caused widespread declines of vulture populations in Africa, especially outside protected areas. Addressing such threats requires the estimation of foraging ranges yet such estimates are lacking, even for widespread (but declining) species such as the African white-backed vulture (Gyps africanus). We tracked six immature African white-backed vultures in South Africa using GPS-GSM units to study their movement patterns, their use of protected areas and the time they spent in the vicinity of supplementary feeding sites. All individuals foraged widely; their combined foraging ranges extended into six countries in southern Africa (mean (6 SE) minimum convex polygon area = 269,1036197,187 km 2) and three of the vultures travelled more than 900 km from the capture site. All six vultures spent the majority of their tracking periods outside protected areas. South African protected areas were very rarely visited whereas protected areas in northern Botswana and Zimbabwe were used more frequently. Two of the vultures visited supplementary feeding sites regularly, with consequent reduced ranging behaviour, suggesting that individuals could alter their foraging behaviour in response to such sites. We show that immature African white-backed vultures are capable of travelling throughout southern Africa, yet use protected areas to only a limited extent, making them susceptible to the full range of threats in the region. The standard approach of designating protected areas to conserve species is unlikely to ensure the protection of such wide-ranging species against threats in the wider landscape. Citation: Phipps WL, Willis SG, Wolter K, Naidoo V (2013) Foraging Ranges of Immature African White-Backed Vultures (Gyps africanus) and Their Use of Protected Areas in Southern Africa. PLoS ONE 8(1): e52813.PLoS ONE 01/2013; · 3.73 Impact Factor