Variabilität im Jagdverhalten des Humboldtpinguins (Spheniscus humboldti) unter verschiedenen ozeanographischen Bedingungen
This study deals with the adjustment of behaviour to environmental conditions and the extent to which these adaptations affect an animal's fitness. The adjustments by Humboldt Penguins (Spheniscus humboldti) to different oceanographic conditions and the consequences of the behaviour for reproduction were investigated. During the austral summer breeding seasons 1997/98 and 1998/99 data on foraging effort, foraging success, and reproductive success were collected at two penguin breeding colonies in Chile. Data on oceanographic conditions were compiled from several sources. The effects of the strong El Niño 1997/98 were given particular attention. The results showed that Humboldt Penguins mainly adjust the horizontal components of their foraging behaviour, particularly foraging trip duration, according to prey availability. It is hypothesised that the highly variable environment puts a selection pressure on the variability of horizontal components of the foraging behaviour, and that the Humboldt Penguin adjusts foraging trip duration according to prey availability balancing proximate with lifetime reproductive success.