Capsule: Supplementary feeding stations provide a useful conservation benefit for vultures, without disrupting their natural movement ecology.
Aims:To understand the effects of providing supplementary food on the movement ecology of vultures.
Methods:We used Global Positioning System tracking devices to monitor the movements of 28 Cape Vultures Gyps coprotheres using feeding stations in South Africa. We calculated home range values and then performed a habitat selection analysis.
Results:We show that aside from roost sites, vulture feeding stations are the most important environmental variable that explains vulture movements. However, we found that the birds ranged over areas without supplementary food and their mean home range values were comparable to those measured before the inception of feeding stations.
Conclusion:Our findings suggest that the use of supplementary feeding sites did not significantly impact on the natural foraging behaviour of the species.
The rehabilitation of injured or poisoned birds, including raptors, is widely practiced even though its conservation value is not well understood. In this study, the survival rate of rehabilitated Cape vultures (Gyps coprotheres) released back into the wild was compared with that of wild-caught birds at a breeding colony in South Africa.The program MARK was used to model survival based on age, sex and whether they were rehabilitated or wild-caught for 405 individual birds. Despite receiving treatment, rehabilitated birds suffered significantly lower survival rates when compared with wild conspecifics of identical age. Annual survival rates (± SE) of rehabilitated and wild-caught birds were 74.8% (± 8.1%) and 91.3% (± 6.3%), respectively. In addition, a population dynamics model was developed to predict 2 future trends based on varying proportions of rehabilitated and wild-caught birds.The population growth rate (λ) for a wild population (i.e. without any rehabilitated individuals) was greater than one or increasing, whereas that for an entirely rehabilitated population was less than one or declining. A stable growth rate, λ = 1, occurred when approximately 50% of the adults were rehabilitated. Together, our results underscore the importance of tackling the causes of these injuries to Cape vultures before rehabilitation becomes necessary.
Tracking studies are often used to inform conservation plans and actions. However, species have frequently only been tracked in one or a few localities, whereas space use can be remarkably flexible, especially in long‐lived species with advanced learning abilities. We assessed variability in space use in the Critically Endangered Hooded Vulture Necrosyrtes monachus by pooling movement data from three populations across the species’ sub‐Saharan range (in South Africa, Botswana, Ethiopia, Kenya, The Gambia and Mozambique). We estimated minimum convex polygons and kernel density estimators (KDEs) and compared monthly home‐range sizes between breeding and non‐breeding seasons, age‐classes and subspecies, accounting for uneven sampling within groups. Mean (± sd) monthly home‐range sizes (95% KDEs) for adult Hooded Vultures from southern (12 453 ± 21 188 km2, n = 82) and eastern Africa (3735 ± 3652 km2, n = 24) were 103 and 31 times larger than those of conspecifics from western Africa (121 ± 98 km2, n = 48). This may relate partly to subspecific differences, and individuals with small home‐ranges in western Africa and Ethiopia were trapped in urban environments. Regional variation in space use by Hooded Vultures may be linked to flexibility in feeding behaviour (degree of commensalism) which may arise in response to resource availability and persecution in different areas. Age‐class also affected monthly home‐range sizes, with immature birds generally having larger monthly home‐range size estimates than adults. Our results highlight the flexibility of Hooded Vultures in terms of their home‐range sizes and suggest that home‐range sizes differ between populations and individuals, depending on the extent of human commensalism. Our results also reaffirm the importance of international co‐operation in conservation efforts aimed at protecting this wide‐ranging, non‐migratory species.
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