DRONE-RECORDED AGGRESSIVE BEHAVIOR TOWARD A MOTHER-CALF PAIR OF GUIANA DOLPHINS (Sotalia guianensis) IN SOUTHEASTERN BRAZIL: A RARE BEHAVIORAL OBSERVATION

Aggression toward mother and calf of Guiana dolphin in Brazil

Abstract

Cetaceans exhibit complex social behaviors, ranging from cooperation to aggression. In situations of resource scarcity or reproductive competition, males may attack females with calves to induce the return of the estrous cycle, a behavior that has already been documented in several odontocete species. For Guiana dolphins (Sotalia guianensis), this type of aggression is rare and has been documented only once in Sepetiba Bay (Rio de Janeiro, Brazil) through direct observation. In April 2024, a new episode was recorded, when four adults chased a mother and her calf, with attempted copulation and physical aggression. The use of drones was essential for obtaining a detailed description of the interaction. This record highlights the need to investigate the ecological factors underlying this behavior in Guiana dolphins, while also demonstrating the potential of remote monitoring technologies to expand the knowledge of their behavioral ecology.