THE DIVING BEHAVIOR OF MAGELLANIC PENGUINS AT PUNTA-NORTE, PENINSULA VALDES, ARGENTINA

During November and December 1994 and December 1995, the diving behavi or of nine Magellanic Penguins (Spheniscus magellanicus) breeding at P eninsula Valdes,,Argentina was studied using time/depth recorders. Bir ds spent most of their time underwater close to the surface although t here 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 individu al ever dived deeper than 12 m during darkness. There were positive re lationships between a number of dive parameters and maximum depth reac hed during the dive: total dive duration, descent duration, ascent dur ation, 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 de pth during the ascent. The dive patterns exhibited by Magellanic Pengu ins were similar to those of other penguin species. More detailed comp arison with other congeners showed differences in dive angles and dive durations as a function of maximum dive depth. These could not, howev er, be definitively ascribed to species-specific differences because i ntra-specific inter-site variability appears high.