Density-dependent productivity in a colonial vulture at two spatial scales.

摘要: Understanding how density dependence modifies demographic parameters in long-lived vertebrates is a challenge for ecologists. Two alternative hypotheses have been used to explain the mechanisms behind density-dependent effects on breeding output: habitat heterogeneity and individual adjustment (also known as interference competition). A number of studies highlighted importance territorial species, but less information exists processes colonial species. For these, we expect operate at two spatial scales: colony unit. In this study, long-term data from recovering population Cinereous Vultures (Aegypius monachus) southern Spain. We analyzed set with 2162 attempts four colonies over nine-year period (2002-2010) evaluate environmental influencing output. Our results suggest that productivity subject nest site scale best explained by competition. Factors intrinsic each colony, well constraints linked physiography human presence, also play role regulatory processes. detected existence trade-off between disadvantages nesting too close conspecifics benefits coloniality. These could be mediated agonistic interactions pairs derived social sharing individuals. propose may defining structure hold true other bird findings important management implications conservation threatened