Flexible foraging for finding fish: variable diving patterns in Magellanic Penguins Spheniscus magellanicus from different colonies
SALA, J., WILSON, R., FRERE, E. & QUINTANA, F.
INTERNATIONAL JOURNAL OF ORNITHOLOGY
Año: 2014 vol. 155 p. 801 - 817
Seabirds have to deal with environmental variabilityand are predicted to modulate foraging behavior tomaximize fitness, with particularly strong selection pressurefor optimal behavior during chick provisioning whenenergy demands are high. We reported data from 42breeding birds equipped during the early chick-rearingperiod with depth recorders at four different colonies[Punta Norte (42S), Bahı´a Bustamante (45S), PuertoDeseado (47S) and Puerto San Julia´n (49S)] in patagonianArgentina. Although Magellanic penguins are purportedto show little flexibility in foraging behavior, wediscovered marked inter-colony differences in divingbehavior. Even though the southern marine ecosystems, ingeneral, and the area exploited by Magellanic penguinsfrom the studied colonies, in particular, are usually characterizedby their stability, we cannot entirely exclude thatinterannual differences may have also affected our results.The colonies located in the center of the breeding distribution,Bahı´a Bustamante and Puerto Deseado, showed thegreatest diving and foraging effort with Bahı´a Bustamantepenguins having the deepest and longest dives of all birdsand requiring the longest post-dive recovery durations atthe surface. Puerto Deseado had the birds with the highestvalues of diving effort parameters. Penguins from bothcolonies also had the highest descent and ascent ratesduring dives. We assume that the clear variation in divingbehavior reflects the response of the birds to the varyingprey types and availability around the different colonies,but note that, despite this, some colonies fare markedlybetter than others in breeding