Nest tree selection by White-backed Vultures (Gyps africanus) in South Africa, does tree health play a role?

Abstract

White-backed Vultures (Gyps africanus) are classed as Critically Endangered, both globally across their African range, and regionally in Southern Africa. For targeted conservation efforts to be successful, we must first understand this species’ habitat requirements. We investigated the White-backed Vulture’s nesting site preferences in the Kempiana and Manyeleti Nature Reserves in north-eastern South Africa. We collected data on six parameters for 205 trees across these two reserves. These parameters included: (i) tree species, (ii) tree height, (iii) trunk circumference at 0.3 and 1.3 m, (iv) canopy width, and (v) signs of damage (debarking, fire, insect presence, fungi). We focused on the impact of tree structure and tree health on vulture nesting site selection, and we classified trees into health categories based on their cumulative damage scores. Our results showed that Diospyros mespiliformis was the most used nesting tree species. A significant portion of trees (68.8%) were ‘healthy’, while the rest were classified as ‘unhealthy’, with debarking being the most severe and common type of damage. However, statistical analyses revealed no significant associations between tree health status and tree characteristics such as height, circumference and canopy width. Additionally, there was no significant relationship between vulture nest presence and tree health status. Vultures appeared to select nesting trees based on their size, particularly their circumference, rather than their health status. Damage from debarking, primarily caused by elephants, was more prevalent among larger trees, which may limit the availability of suitable nesting sites. Conservation efforts should consider protecting larger trees and managing elephant populations to ensure the availability of nesting sites for this critically endangered species. Further research is needed to explore the long-term impacts of different damage types on tree health and vulture nesting success.