Breeding Habitat and Factors Affecting the Cliff Selection by Egyptian Vultures in Central-West Nepal

Abstract

The Egyptian Vulture (Neophron percnopterus) is a resident species in Nepal, and breeds in the lower mountains in the southern plains of Nepal. Nest-site availability is an important factor that determines the population growth of vultures; however, such information is lacking in South Asia. We here describe the characteristics and spatial distribution patterns of Egyptian Vultures' nest sites in the foothills of the Himalayan Mountains in central-west Nepal, and the factors that influence their nest-site selection. From 2012 through 2018, we surveyed all the known and potential nesting cliffs of the Egyptian Vulture located in the Pokhara Valley and its periphery during the nest building and nestling-rearing periods. In addition, we used generalized linear models to analyze the influence of landscape configuration, topography, and human disturbance factors on nest-site selection. We found a total of 21 occupied nests in a sampled area of 346 km2. Nests were not uniformly distributed, and the nearest neighbor distance between nests averaged 8.8 ± 6.1 km. Nests were located at an elevation of 523–1644 masl on cliffs with a mean height of 20.1 ± 12.2 m; 76% were in caves and 24% were on open ledges. Our models suggested that cliff height, anthropogenic trophic resources, and altitudinal variation around the cliff were the main determinants of the nesting cliff selection. Selection of small cliffs closer to food sources could minimize energy expenditure during food delivery and interspecific competition for nesting sites. The high altitudinal variation around the nest sites suggest that Egyptian Vultures preferred heterogeneous habitat, which might also be relatively difficult for humans to access and use easily.