An Aggressive Interaction Between Bottlenose Dolphins (<I>Tursiops truncatus</I>) and Estuarine Dolphins (<I>Sotalia guianensis</I>) in Southern Brazil

Abstract

For the first time we report on an aggressive interaction between wild bottlenose dolphins (Tursiops truncatus) and estuarine dolphins (Sotalia guianensis) observed in Baia Norte, southern Brazil. Three bottlenose dolphins aggressively herded a Sotalia guianensis calf, which was the main target of the aggressive and threatening behaviours of the bottlenose dolphins. Another two to four adult S. guianensis were involved in the interaction and were constantly chased by the bottlenose dolphins. After approximately two hours, the bottlenose dolphins left the calf and the area, and no dead or wounded animals were seen afterwards. We provide a detailed spatial and temporal description of the interaction, and discuss the potential causes of this event.