Modelling the distribution of short-toed eagle (Circaetus gallicus) in semi-arid Mediterranean landscapes: identifying important explanatory variables and their implications for its conservation

Mediterranean semi-arid landscapes are currently experiencing accelerated land use changes which are affecting species distributions. An important fraction of the European short-toed eagle (Circaetus gallicus) population, a specialised snake predator, breeds in this kind of landscapes. Information on the habitat characteristics that may affect the occurrence of this species is of paramount importance to try to evaluate how this species could be affected by ongoing territory changes. In this study, we use hierarchical partitioning analysis to identify environmental variables (natural vegetation, agricultural uses, hydrological web, topography, human pressure and climate) at two resolution scales (1 and 4 km²) that may influence the presence of the short-toed eagle in a populated Mediterranean region in southeastern Spain. Results were highly consistent between scales. Forest was the most important variable determining the presence of the short-toed eagle in the study area, showing a positive effect, particularly those inland forests with nearby presence of sunny open scrublands where the species may find its prey. On the contrary, herbaceous crops and all variables related to human pressure, including urbanisations, dispersed houses and roads, are negatively affecting the occurrence of the species. These variables are strongly related to the main driving forces that change landscapes in our study area, including the abandonment of traditional territory uses and the expansion of urbanised areas. These results indicate that the increasing number of housing developments projected in inland areas would have a detrimental effect on the short-toed eagle, especially if they are located close to pine forests and rivers.