Winter migration of rockhopper penguins ( Eudyptes c. chrysocome) breeding in the Southwest Atlantic: is utilisation of different foraging areas reflected in opposing population trends?

KLEMENS PÜTZ,; RAYA REY, ANDREA; ADRIAN CARLOS MIGUEL SCHIAVINI; ANDREA CLAUSEN,; BERNHARDT LÜTHI,

POLAR BIOLOGY

Springer Verlag

Lugar: Heidelberg; Año: 2006 vol. 149 p. 125 - 137

0722-4060

A total of 22 magellanic penguins (Spheniscus magellanicus) from Isla Martillo in the Beagle Channel, Argentina, was successfully satellite tracked in 2004 (n = 7), 2005 (n = 7) and 2006 (n = 8) to monitor their winter migration after moult. With one exception, all penguins left the island in an easterly direction, rounded Cabo San Diego, the southeasterly tip of South America, and continued northwards in inshore waters mostly less than 50 km away from the coast, only occasionally venturing further offshore. By the end of the transmission period, the most northerly positions were obtained from birds foraging in the area of the Peninsula Valdés, Argentina, at a latitude of around 42°S, about 1,500 km away from their breeding site. The mean maximum distance to the colony was, however, only 624 ± 460 km, whereas the mean minimum distance covered was 1440 ± 685 km, which was mainly due to the fact that most individuals remained in certain coastal areas for various time periods until transmissions ceased. One magellanic penguin, however, migrated northwards in the Pacific Ocean. The northbound inshore migration of magellanic penguins is thus assumed to be driven by the formation and dissolution of areas characterised by enhanced primary productivity as the season progressed and light levels and day lengths decreased. However, these findings also imply that magellanic penguins are increasingly threatened by human activities, such as fisheries or oil pollution, which are much more pronounced in coastal areas and intensify as penguins migrate northwards. The results obtained are discussed with regard to these threats and related to those obtained from conspecifics from other breeding sites.