Seascape modeling of southern giant petrels from Patagonia during different life-cycles

Abstract

Presence-only models such as Ecological Niche Factor Analysis (ENFA) compare distributions of environmental variables and species, generating habitat suitability (HS) maps. Here, we determined the factors affecting distribution of southern giant petrels (SGP) from northern Patagonian colonies (Isla Arce: 45° 00ʹS; 65°29′W, and Isla Gran Robredo: 45°08ʹS; 66°03′W) using ENFA, improving estimates of their potential year-round feeding habitats. Data on movements of 17 adult and 9 first-year juvenile SGP were gathered using satellite telemetry. Model eco-geographical variables (EGV) overlapped the tracked animals. The resulting HS maps included most of the tracking locations along the Argentinean Shelf and reflected characteristics that congregate procellariiformes elsewhere. Wind conditions and primary productivity shaped foraging HS of petrels over the year. However, different EGVs influenced this population differently depending on the requirements of their life stage. For example, 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 specializations. Contrarily, wintering petrels showed plasticity in the selection of their foraging environments being distribution of fisheries one of the variables influencing their distribution. This study highlights the importance of the Argentinean Shelf for conservation of the marine environment.