Abstract:
Half of the world population of king penguins breed at the sub-Antarctic Crozet Archipelago and Prince Edward Islands. Because of their large biomass and high energy requirements, and thus their large functional effects on marine ecosystems they are considered sentinels of ocean health. Determining the influence of their foraging behaviour on their population responses is thus critical for understanding the impact of climate variability on the marine ecosystem. Two recent studies revealed a hitherto unknown foraging area for king penguin breeding adults from Marion Island (Prince Edward Islands. and juveniles from Possession Island (Crozet Archipelago. during winter (the least known part of their life cycle.. This area is situated around 800km southwest of Marion Island along the Southwestern Indian Ridge and almost 2000km off the Crozet archipelago. Combining for the first time tracking and diving datasets from the two island groups allowed a refined examination of the use of this area by two populations of top predators potentially in competition for the same food. The productivity of this area is likely due to interactions between the bathymetry and currents. Habitat selection models including oceanographic covariates such as sea level anomalies, currents, eddies and mixed layer depth allowed the identification of important, dynamic foraging habitat common to both populations, at a fine spatial scale. We discuss the importance of this zone with respect to the closer Polar Front, especially used by the breeding birds during summer. The area may be particularly important for king penguins in winter - the period of scarcity of their main prey resources. The area is also used by many others marine predators such as penguins, seals, whales and albatrosses. Understanding the area’s significance for these two important king penguin populations is thus critical, especially given projected poleward shift of the Antarctic Polar Front. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
