Space and resource use of Cape Vultures at an isolated colony in the Western Cape: importance of livestock agriculture to this thriving population

Adams, Tevin

Space and resource use of Cape Vultures at an isolated colony in the Western Cape: importance of livestock agriculture to this thriving population

Thesis / Dissertation

2024

Abstract

Vultures are keystone species providing crucial ecosystem services, yet their numbers have declined globally, including in Africa, due to various threats. Understanding their habitat use and resource needs is vital for conservation. The Cape Vulture (Gyps coprotheres) colony at Potberg in the De Hoop Nature Reserve, Western Cape, South Africa, is an isolated population 600 km from the nearest colony. Despite monitoring and population growth over decades, little is known about their movement patterns. The colony now faces threats from regional wind farm developments. Thus, it's essential to identify critical habitats and food sources, particularly fallen livestock, and understand local farmers' attitudes toward these vultures to secure their food supply for the future. In this study, we use GPS tracking data from juvenile Cape Vultures that were tagged at this colony. Using the tracking data from six birds with sufficient data we mapped the core areas of movement between April 2022 (after their post fledging dependency period) and November 2023. Three of the six bird tracking devices failed during the tracking period. The three remaining birds continued transmitting tracking data, and between September 2023 and November 2023 were also used to identify potential feeding sites. These feeding sites provided us with information on the areas used for foraging, and by visiting these sites were also able to confirm the food resources that were exploited by this population. In total 44 potential feeding sites were identified and ground-truthed. Of the 44 sites visited, 24 sites had carcasses present whereas at 20 no carcasses were found. Of the 24 sites with carcasses found, 21 (88%) were sheep (Ovis aries) carcasses located on private farmlands and 12% were cattle (Bos taurus) carcasses located at a vulture restaurant 3 km from the colony, and also on private farmland. Thus, we confirmed that this population mainly foraged outside of the protected area where the colony is located and mainly on private farmland. Additionally, we interviewed 20 farmers within the foraging range of this population. Based on our questionnaire, we found that the majority of the farmers view vultures positively, however, most farmers also suggested that sheep farming was reducing in the area because it was becoming less profitable. We conclude that this population is currently heavily reliant on local farming practices, which are vulnerable to change in the short to medium term due to profitability issues in the livestock sector, which could therefore pose a substantial risk to the continued stability of this important population.

Keywords

Biological Sciences

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