Tuesday, 12 February 2013

Call for birders to look out for Cape Vultures with tags

The Cape Vulture (Gyps coprotheres) is the only colonial South African vulture species nesting on cliffs [1,2]. Its range is restricted to southern Africa, with breeding occuring in Botswana and South Africa. Breeding was recently reported to have ceased in Namibia [3]. The formerly widespread population of about 440 breeding colonies in the early 1900s declined to about 167 breeding colonies at the end of the 20th century [4]. The species is listed as vulnerable due to ongoing population declines, whereby poisoning, power-line collision, hunting for the local muthi market and declining food resources are the main threats to its existence. Nowadays, an estimated number of 3,400 breeding pairs exist in southern Africa [1,5]. A number of 18 core colonies in southern Africa hold about 80% of the world's Cape Vulture population [6]. 
The breeding biology of the species is well-known [5,6]. Adult birds are residential colonial cliff breeders that pair for life [1]. Breeding starts in April to June and first fledging occurs towards between the end of October and mid-January [1]. Juvenile birds stay near their colony until the next breeding season, when they start wandering from their natal colony and eventually, at the age of about six years, settle at a colony for breeding. Our understanding of the movement of individual vultures between colonies is limited. However, understanding the population dynamics and movement among remaining populations is crucial for developing management strategies for the conservation of these species [7]. 

GPS tracking of birds with the help of satellite transmitters produces accurate information on the movement patterns of individuals. Unfortunately, high costs limit the number of transmitters that can be deployed. The use of wing tags (see photograph below) has proved to be an effective method to complement the information from the transmitters, increasing the probability of re-sightings of marked birds [8]. Wing tags have the advantage of being clearly visible even from long distances. However, the method strongly depends on feed-back from the public in terms of re-sightings of the tagged birds and notification to the data collectors.

Together with experts from the Cape Vulture Task Force of the Endangered Wildlife Trust, VULPRO, University of KwaZulu-Natal (UKZN) in collaboration with Eastern Cape Parks and Tourism Agency (ECPTA) as well as Ezemvelo KZN Wildlife, workers on two recent research projects are currently investigating the movement of adult and juvenile Cape Vultures in southern KZN and on the northern Wild Coast. In the course of two capturing events, researchers have fitted a number of Cape Vultures with transmitters and tags so that individual birds can be recognised from a distance. Some of the captured birds were only fitted with tags before being released.

The birding community can assist the researchers with the information gathering process by reporting the tag number, date and location of any sightings of tagged Cape Vultures to either of the following contacts:

·VULPRO, Kerri Wolter, kerri.wolter@gmail.com or 0828085113, www.vulpro.com

·Ezemvelo KZN Wildlife, Sonja Krueger, 0828774122, skruger@kznwildlife.com

·Endangered Wildlife Trust, Andre Botha, 0829625725, andreb@ewt.org.za

1.        Mundy P, Butchart D, Ledgert JA, Piper SE (1992) The vultures of Africa. South Africa: Acorn Books & Russel Friedman Books, Randburg & Halfway House.

2.        Pickford B, Pickford P (1989) Cape Vulture. Southern African Birds of Prey. Cape Town: Struik Publishers. pp. 21–23.

3.        Hockey P, Dean W, Ryan P, editors (2005) Roberts - Birds of Southern Africa. VIIth. Cape Town: The Trustees of the John Voelcker Bird Book Fund.

4.        Barnes, K. N. 2000. The Eskom Red Data Book of birds of South Africa, Lesotho and Swaziland. BirdLife South Africa, Johannesburg.

5.        Piper SE (1994) Mathematical demography of the Cape Vulture Gyps coprotheres. Volumes 1 & 2, PhD thesis. Cape Town: University of Cape Town.

6.        Boshoff AF, Anderson MD (2006) Towards a conservation plan for the Cape Griffon Gyps coproteres: identifying priorities for research and conservation action. Port Elizabeth: Centre for African Conservation Ecology, Nelson Mandela Metropolitan University.

7.        Agudo R, Rico C, Hiraldo F, Don├ízar J a. (2011) Evidence of connectivity between continental and differentiated insular populations in a highly mobile species. Diversity and Distributions 17: 1–12.

8.        Botha A (2007) A review of colour-marking techniques used on vultures in southern Africa. Vulture News 56: 52–63.

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