Inter-colony comparison of diving behavior of an Arctic top predator: implications for warming in the Greenland Sea

The goal of this study was to assess how diverse oceanographic conditions and preycommunities affect the foraging behavior of little auks Alle alle. The Greenland Sea is characterizedby 3 distinct water masses: (1) the East Greenland Current (EGC), which carries Arctic waterssouthward; (2) the Sørkapp Current (SC), which originates in the Arctic Ocean but flows northalong the west coast of Spitsbergen; and (3) the West Spitsbergen Current (WSC), which carrieswarm Atlantic-derived water north. Each of these 3 water masses is characterized by a distinctmesozooplankton community. Little auks breeding adjacent to the EGC have access to large,lipid-rich Calanus copepods, whereas those adjacent to the SC have medium sized prey, whilethose near the WSC are limited to even smaller, less profitable prey. We used time&\#8722;depthrecorders to compare the time allocation and diving behavior of little auks adjacent to each ofthese 3 water masses. We predicted that birds in the EGC would not have to forage as intensivelyas those in the SC or WSC. We found that little auks foraging in the EGC spent less time at sea,spent less time flying, dived less often, made fewer long, deep dives, and made fewer V-shapedsearching dives. This indicates that the EGC provides a more favorable foraging environmentthan do the warmer water masses to the east. Comparing the foraging behavior of little auk populationsconfined to Arctic versus Atlantic-influenced waters can provide insight into the potentialimpacts of future warming in the Greenland Sea.