At-sea distribution, movements and diving behavior of Magellanic penguins reflect small-scale changes in oceanographic conditions around the colony

BLANCO, G. S.; GALLO, L.; PISONI, J. P.; DELL?OMO, G.; GEREZ, N. A.; MOLINA, G.; QUINTANA, F.

MARINE BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2022 vol. 169

0025-3162

Penguins are highly specialized divers that are expected to reflect environmental variation by adjusting their foraging behavior.We performed a comprehensive analysis of the at-sea distribution, diving, and foraging performance of Magellanicpenguins (Spheniscus magellanicus) during the early chick-rearing period over two consecutive breeding seasons. The studywas conducted at Cabo dos Bahías, (44° 54′ 50″ S; 65° 32′ 37″ W) a breeding colony located south of the latitudinal range ofpenguins? main prey item Argentine anchovies (Engraulis anchoita). We also linked penguin foraging behavior to sea surfacetemperature (SST) to examine how birds cope with differences in oceanographic conditions. For this, we instrumented 37adult penguins (18 in 2015 and 19 in 2016) with data loggers. In addition, we recorded chick growth in body mass duringthe first 12 days of life. Overall, the diving patterns of adult Magellanic penguins were similar in both breeding seasons.However, during 2015, adult breeders spent more time at the sea surface between foraging dives and performed more foragingdives per hour. The time spent foraging was higher in 2016 than in 2015. Foraging penguins also expanded their foragingrange more than 100 km during 2016. Temperature records gathered by diving penguins during 2016 showed significantlyhigher temperatures, both at the sea surface as well as at the bottom of dives. Adults performed a higher foraging effort andchicks gained weight faster during 2016. Site-specific variability in prey distribution and abundance may be responsible forinter-seasonal discrepancies in the foraging and diving patterns. We reasoned that any environmental change could cause ashift in the distribution of anchovies, which would change the foraging behavior of penguins as they attempted to optimizetheir chick growth. Penguins from Cabo dos Bahías appear to face this environmental challenge with a highly sensitive at-seaforaging performance by increasing foraging effort when necessary.