Does habitat use and ecological niche shift over the lifespan of wild species? Patterns of the bearded vulture population in the Western Alps

We analysed bearded vulture (Gypaetus barbatus) occurrences collected through long-term monitoring (from 1993 to 2010) in the Western Alps (1) to test whether ecological niches shift due to individual development and (2) to verify whether these patterns could reflect their spatial distribution. Thus, we compared the distribution patterns of three age classes ('young', 'sub-adults' and 'adults') through the K-select analysis. We then computed ten species distribution models (SDMs) and their average prediction to test for differences in age class distribution. The K-select analysis showed highly significant differences in the ecological niche among all the age classes and we also found highly significant differences in all the SDMs among the three age classes considered. Our results quantitatively showed that target species exhibits age specific shifts in the ecological niche and changes in the spatial distribution of individuals. Our methods are potentially widely applicable for testing differences among age classes of other species and thus, defining the best conservation actions (such as re-introduction) by taking into account different requirements in different stages of the individuals' life.