Using high‐resolution remote sensing to quantify nest‐site characteristics of White‐backed Vultures (Gyps africanus) in Karingani Game Reserve, Mozambique

Identifying effective approaches to measuring habitat requirements for elusive and difficult-to-study species is an important component of ecological research, particularly for species of conservation concern. The continued decline of critically endangered White-backed vultures (WbVs) Gyps africanus calls for urgent intervention and an increased understanding of their nesting requirements to improve conservation of suitable nesting trees. However, there is currently little research on the nesting preferences of WbVs, and few measurements on how variation in individual tree architectures or their surrounding area influences WbV nest-site selection, in part due to challenges associated with collecting such data. We combined remotely sensed Light Detection and Ranging (LiDAR) data and Red-Green-Blue (RGB) imagery with helicopter surveys of nest sites to quantify nest-site selection of WbVs in Karingani Game Reserve (KGR), Mozambique. The LiDAR and RGB orthomosaics allowed for precise and accurate measurement of various tree-level characteristics: canopy height, canopy area, canopy roughness, nest orientation and peripheral position. Distance to water and surrounding vegetation cover, canopy height, and vegetation roughness within 100 m of nesting trees were also measured. We found that WbVs in KGR preferentially nest in trees with a mean height of 14 m, with large variation and roughness within their canopy, and with large canopy areas (mean > 160 m²). WbVs in KGR were found to mainly position their nests on the northern side of trees, but with no selection in relation to the canopy edge. The approach of using LiDAR and RGB imagery was found to be effective for measuring tree-level variables in a time-effective and accurate manner, and allowed for improved understanding of the specific requirements of WbVs when selecting a tree to nest in, which can in turn inform habitat management to ensure the persistence of nest trees and the survival of the species.