Density‐Dependent Productivity in a Colonial Vulture at Two Spatial Scales

Abstract

What determines the breeding success of colonial animals? Working with data from a long-term monitoring program at four Cinereous Vulture ( Aegypius monachus ) colonies in southern Spain, we evaluated the infl uence of environmental and population factors on breeding performance, both at the nest site and colony scale. At both scales, density-dependent processes regulated breeding productivity and were best explained by interference competition (i.e., at higher densities increased competition for resources reduced productivity). We also detected the existence of a trade-off between the benefi ts of coloniality and the disadvantages of nesting too close to conspecifi cs. We propose that this trade-off may play a role in defi ning how colonies are spatially structured in this and other colonial bird species.

Factors affecting population regulation of a colonial vulture

“…Studies on similar systems have mainly reported regulation through IAH (Fern andez et al 1998, Oppel et al 2015, Fern andez-Bellon et al 2016) with a few studies on colonial species supporting the HHH (Kokko et al 2004). Studies on similar systems have mainly reported regulation through IAH (Fern andez et al 1998, Oppel et al 2015, Fern andez-Bellon et al 2016) with a few studies on colonial species supporting the HHH (Kokko et al 2004).…”

“…The HHH has obtained a great deal of support from studies of territorial species, as under increasing populations there is no increase in high-quality territories, and resources are monopolized by territory holders (Tella et al 2001). Notwithstanding, in colonial species IAH seems to play a major role (Newton 2013) and the scant literature in colonial raptors suggests an important function of IAH (Bretagnolle et al 2008, Fern andez-Bellon et al 2016. The densitydependent effects can take place at different spatial scales: at large scales, IAH might arise from competition for better feeding areas, preferential access to resources, food depletion or the need to travel further distances to find food (e.g.…”

How to fit the distribution of apex scavengers into land‐abandonment scenarios? The Cinereous vulture in the Mediterranean biome

“…The species breeds in loose colonies reaching up to hundreds of pairs (45–312) with nests separated by distances from a few metres to several kilometres apart. It usually nests on the top of large trees (Cramp & Simmons, ; Dobado & Arenas, ; Moreno‐Opo & Guil, ) avoiding areas with high human disturbance (Donázar, Hiraldo, & Bustamante, ; Fernández‐Bellon, Cortés‐Avizanda, Arenas, & Donázar, ; Morán‐López, Sánchez Guzmán, Borrego, & Sánchez, ; Poirazidis, Goutner, Skartsi, & Stamou, ). The Cinereous vulture feeds on small‐sized and medium‐sized carcasses being the European rabbits ( Oryctolagus cuniculus ) the most important item (3%–60% of diet) in Mediterranean regions (Corbacho, Costillo, & Perales, ; Hiraldo, ).…”

A recipe for scavenging in vertebrates – the natural history of a behaviour

“…In flight, birds are able to gather a wealth of information from other foragers, be they conspecifics or otherwise (Jackson et al 2008, Kane et al 2014, Moleón et al 2014b). Again, returning to vultures, the genus Gyps consists of highly social and colonially nesting species (Fernández-Bellon et al 2015). These behaviours allow them to forage far more efficiently because one bird can scrounge information on the location of food from another successful forager (Cortés-Avizanda et al 2014).…”