Too Much is Bad: Increasing Numbers of Livestock and Conspecifics Reduce Body Mass in an Avian Scavenger

摘要

Variation in body mass can serve as early warning signals of changes in the fitness prospects of animal populations facing environmental impacts. A 19-yr monitoring of changes in the body mass of Canarian Egyptian vultures (Neophron percnopterus) shows that it would be dependent of the availability of small ver- tebrate carcasses, which would be favored by variability in primary productivity, but depleted by high livestock pressure. In addition, increasing vulture population numbers negatively affect body mass, suggesting density-dependent competition for food. Individual plastic traits may help to assess the response of secondary consumers to human-induced environmental changes.