THE FIRST PAN-AFRICAN STUDY ON VULTURE MOVEMENTS
Dr Lindy Thompson, Project Coordinator: Vulture Conservation and Research, EWT Birds of Prey Programme
Since 2016, we have been working with collaborators across Africa on a study on the movements of the critically endangered Hooded Vulture. This project was the brainchild of Dr Keith Bildstein, a world expert on raptor migration, and previous Director of Conservation Science at Hawk Mountain Sanctuary, USA. Keith brought together scientists working in The Gambia, Kenya, Botswana, Mozambique, South Africa and Ethiopia, who had tagged a total of 30 Hooded Vultures. By pooling their tracking data, these scientists were able to compare the movements of Hooded Vultures in eastern, western and southern Africa, with some very interesting results. We looked at Hooded Vulture home-range size, and whether this was affected by age, breeding season or region. Breeding season didn’t really affect Hooded Vulture home-range size much, but we found big differences between birds in different regions of Africa. Hooded Vultures in southern Africa had massive monthly home-range sizes (12,453 km²), while those in eastern Africa were much smaller (3735 km²), and Hooded Vultures in western Africa had the smallest monthly home-range sizes (only 121 km²). We believe this variation is related to how Hooded Vultures feed in different parts of their range. The birds in West Africa are a different subspecies to the Hooded Vultures we get in southern and East Africa. The northern subspecies in West Africa often feed at rubbish dumps or on scraps left by people at markets, and they can be very relaxed around people. In contrast, the southern subspecies in southern and eastern Africa feed mainly in wild areas, and they do not usually feed close to people. This means that for Hooded Vultures in West Africa, food is predictable, the birds know when and where to find it, so they do not need to spend much time travelling around in search of food, and this translates into comparatively tiny home-range sizes. Our southern African Hooded Vultures on the other hand must travel massive distances in search of food, because there is no way of knowing when or where the next carcass may be found, and this results in enormous home-ranges. We also found that younger birds have much bigger home-ranges than adults, possibly because they are exploring new areas and they aren’t yet tied down to a nest-site. Vultures’ home-ranges overlap international borders, which highlights the need for international cooperation in vulture conservation activities. Our results will be useful for conservation planners when drafting national management plans for vultures.
You can read a summary of the article here https://doi.org/10.1111/ibi.12836, or email Lindy (LindyT@ewt.org.za) to request a copy of the full article.
We are grateful to all our funders, including AZA Conservation Grant Fund, Bowling for Rhinos, Denver Zoo, Detroit Zoo, GreenMatter, San Diego Zoo Global, National Geographic Society, Raptors Botswana, The Wallace Research Foundation, The Rufford Foundation, Fulbright, the Wilderness Wildlife Trust, the National Research Foundation, and Wildlife Computers Inc.
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