The diving behavior of Magellanic Penguins at Punta Norte, Peninsula Valdes, Argentina

During November and December 1994 and December 1995, the diving behavior of nine Magellanic Penguins (Spheniscus magellanicus) breeding at Peninsula Valdes,,Argentina was studied using time/depth recorders. Birds spent most of their time underwater close to the surface although there was extensive activity at depths around 60 m. Maximum dire depth recorded was 97 m which likely reflects the water depth. Maximum dive depth was clearly regulated by ambient light intensity and no individual ever dived deeper than 12 m during darkness. There were positive relationships between a number of dive parameters and maximum depth reached during the dive: total dive duration, descent duration, ascent duration, bottom duration (the time spent at the deepest part of the dive), rate of change of depth during the descent and rate of change of depth during the ascent. The dive patterns exhibited by Magellanic Penguins were similar to those of other penguin species. More detailed comparison with other congeners showed differences in dive angles and dive durations as a function of maximum dive depth. These could not, however, be definitively ascribed to species-specific differences because intra-specific inter-site variability appears high.