| The resident population of estuarine dolphin, Sotalia guianensis (P.J. van Bénéden, 1864), in Norte Bay, Santa Catarina, southern Brazil, was studied from 2000 to 2003. Systematic one-day cruises were undertaken aboard a 5 m sail boat equipped with an outboard motor. Applying the focal-group method, information such as geographical position, predominant behavioural patterns, group size, cohesion index and the presence of calves, were registered at every five-minute interval, totalling 198 hours of direct observation of the dolphins. The estuarine dolphin used preferential areas for each behavioural pattern. The mean group size was approximately 29 individuals, and the presence of calves occurred throughout the entire year, but with a significant increase... |
