Breeding biology of Magellanic Penguins (Spheniscus magellanicus) at the Beagle Channel: interannual variation and its relationship with foraging behaviour

SCIOSCIA G; A RAYA REY; A SCHAIVINI

journal of ornithology

springer

Año: 2016 p. 1 - 13

Interannual variation in seabird foraging orreproductive behaviour may reflect fluctuations in marineresources. In this study, we evaluated different foragingand breeding parameters of Magellanic Penguins(Spheniscus magellanicus) from Martillo Island in theBeagle Channel, and the relationships between theseparameters at different stages within the season (incubation,early and late chick-rearing) over three consecutivebreeding seasons (2006?2007, 2007?2008 and 2008?2009).In 2007, we observed greater adult foraging effort (longerforaging trip duration and vertical travel distance, VTD)and lower chick feeding frequency, together with a slowergrowth rate and later fledging date of chicks, which wesuggest was linked to lower food availability near thecolony that year. The increased foraging effort appeared tobe compensated by enhanced feeding activity (e.g., numberof wiggles per dive). However, this increase did not coincidewith a larger amount of food load brought to colony,which may have been due to a change in the type or size ofprey consumed by the penguins. Magellanic Penguins fromMartillo Island showed great plasticity in foraging behaviour,as evidenced by changes in consumed prey type orincreased foraging effort and feeding activity when theconsumption of their main prey item, Sprattus fuegensis,seemed to decrease. Moreover, during this particularbreeding season, although the growth rate of chicks waslower, the breeding success remained constant throughoutthe study period, suggesting that the penguins managed tocompensate for the apparent decrease in Fuegian sprat.