Selezione dell'habitat del più piccolo uccello marino europeo nel Mediterraneo

Habitat selection is one of the central themes of ecological and evolutionary studies due to its influence on foraging behavior, niche separation, life-history tactics and adaptations. There is an increase need in identifying important marine areas to preserve ocean biodiversity and its ecosystem services. Characterizing habitat suitability for marine organisms, however, requires an understanding of the environmental heterogeneity over the range in which individuals move. Prey distribution and nutrients in the ocean vary spatially and temporally in response to macroscale fluctuations of oceanographic conditions and mesoscale processes. We investigated how a highly mobile pelagic seabird, during their incubation period, interact with dynamic (i.e., Sea Surface Temperature, chlorophyll-a, eddy kinetic energy) and static (i.e., bathymetry) oceanographic features. We combined direct tracking locations (n = 2883) of Mediterranean Storm-petrels (Hydrobates pelagicus melitensis; n = 39) breeding in four Mediterranean colonies during incubation period over multiple years (2019-2021). We considered near-real-time remotely sensed oceanographic variables and use Generalized Linear Mixed Models (GLMMs) to investigate birds’ habitat selection. We used complete foraging trips locations from the largest colony at Benidorm Island (n = 21) to identify their foraging location (ARS analysis) and the relative importance of each variable in describing the foraging areas of the petrels. Results from this first analysis indicated that water temperature (SST), Chlorophyll-a concentration and kinetic energy are the most important variables that characterize foraging area. Based on these results, we determined the foraging habitat suitability for the western Mediterranean and identified the Alboran Sea, the North Africa coast, the Gulf of Lion and the Ebro River Delta as the most suitable regions. Habitat suitability maps showed an overlap between the area predicted by the model and the observed foraging localizations of petrels from the other three study colonies of s’Espartar, Cabrera and Menorca. This study helped to identify priority conservation areas and diversity hot-spots for a declining seabird species in the Mediterranean Sea.