Intra- and interannual variation in the diet of the Magellanic penguin (Spheniscus magellanicus) at Martillo Island, Beagle Channel

SCIOSCIA G; A RAYA REY; R SAENZ SAMANIEGO; O FLORENTIN; A SCHIAVINI

POLAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2014 vol. 37 p. 1421 - 1433

0722-4060

Knowledge of seabirds? diet at each breedingsite and its temporal variation is key to understanding andevaluating how changes in marine resources affect eachseabird population. In this study, we determined the diet ofMagellanic penguins (MP, Spheniscus magellanicus) atMartillo Island, accounting for sex, breeding stage andyear. We analyzed a total of 144 stomach contents duringthree consecutive breeding seasons (2006?2007,2007?2008 and 2008?2009) and stages (incubation, earlyand late chick-rearing). MP fed mainly on fuegian sprat(Sprattus fuegensis), which represented 75 % of the biomassconsumed by birds during the entire study. The nextimportant prey was squat lobster (Munida gregaria), followedby Patagonian squid (Loligo gahi). Both sexesconsumed similar prey items. We observed variation in dietrelative composition among breeding years and stages.Fuegian sprat consumption decreased throughout the yearswhereas squat lobster increased. Penguins consumed ahigher proportion of squat lobster and Patagonian squidduring the incubation stage than in the chick-rearing stages,whereas fuegian sprat was almost the only prey itemconsumed during the late chick-rearing stage. MPs showcertain flexibility in the use of resources probably as aresponse to changes in prey populations. Variability in thediet among different reproductive stages could be related tochanges in the distribution and abundance of their mainprey near the colony during the breeding season togetherwith changes in the energy requirements of seabirds.