Navigating unpredictable oceans: mapping fine-scale temporal and spatial variability in little penguin foraging areas

Faced with unpredictable prey in dynamic ecosystems, seabirds have developed strategies to efficiently locate food, particularly during breeding when time and space are constrained. Using 13 yr of GPS data from 422 little penguins Eudyptula minor, we tested whether they rely on consistent foraging areas to reduce search times or respond to dynamic environmental cues. Our results suggest a combination of these strategies, depending on the spatial scale. Little penguins used only 32% of the potential foraging range, concentrating in shallow waters within 70 km and mostly east of their colony, as confirmed by our spatial density models. However, finer-scale analyses using kriging maps showed no recurring foraging hotspots over 13 yr, suggesting high interannual variability in prey availability. Despite this variability, penguins consistently spent more time in the most productive areas and also exploited more areas with favourable environmental conditions to access prey (thermocline, current, waves), even as these conditions shifted within and across breeding seasons. In years of poor conditions, they foraged farther from the colony, resulting in lower breeding success. These results emphasise the adaptability of little penguins to dynamic environmental conditions, but underscore the vulnerability of their foraging and breeding success to oceanographic variability in a climate-impacted ecosystem.