Trophic links in a high-elevation bird species: the Northern Wheatear as prey and predator

Mountains are considered particularly threatened, because of several pressures such as climate change, land-use change and human disturbance. In the Western Alps, the expansion of forest and loss of open grasslands is threatening alpine species. However, our knowledge of even the basic ecology of many mountain species is much lower compared to other habitats, thus hampering our ability to develop conservation strategies for mountain species. This thesis focused on the ecology of an alpine grassland bird, the Northern Wheatear Oenanthe oenanthe. Both intrinsic (influence of male age) and extrinsic (trophic interactions at both lower and higher trophic levels) factors affecting breeding performance were analysed to understand the main demographic drivers. Although many elements of the ecology and demography of alpine birds still need to be explored in depth, this thesis demonstrated that in the short-term, generalist alpine species like the Wheatear may be able to adapt to some effects induced by climate change, like potential variations in food resources. However, this likely ability to adapt to some changes is limited as they do not seem to have the capability to adapt to changes in habitat, being strongly related to open areas. Moreover, the results revealed unexpected interactions as rodents were the main predators of Wheatear nests in alpine grasslands. This showed that overlooking predator-specific effects may limit our capacity to understand and predict ecological processes driving breeding success, emphasizing the need for studies on species interactions