The role of environmental variables in the habitat selection of the Southern Giant Petrel

The Ecological Niche Factor Analysis (ENFA) is a presence-only model that generates habitat suitability (HS) maps by understanding the choices of resources that are unequally used when they are equally available in a study area. Here, we determined the factors affecting foraging distribution of the Southern Giant Petrel (SGP) from northern Patagonian colonies (Isla Arce and Isla Gran Robredo) using ENFA. Data on movements of 17 adults and nine first-year juvenile SGP were gathered using satellite telemetry. Model eco-geographical variables (EGVs) (geographic, biological, and oceanographic) overlapped at a temporal and spatial scale the tracked animals. The resulting HS maps included most of the tracking locations along the Argentinean Continental Shelf. Wind conditions and primary productivity shaped the HS of petrels over the year. However, different EGVs influenced differently this population depending on the requirements of their life stage. Juveniles showed high marginality (values of EGVs different from the mean values available). Breeding adults´ HS was determined by a small range of values within those available, showing high specialization. Contrarily, wintering petrels showed higher plasticity in the selection of their foraging environments. The resulting HS maps of SGP in the present study also congregates different species of seabirds and marine mammals, which highlights the importance of the ACS for the conservation of the marine environment.