Bottlenose dolphins (Tursiops truncatus) aggressive behavior towards other cetacean species in the western Mediterranean

J L Crespo-Picazo,F J Aznar,M Melero,V Marco-Cabedo,C Rubio-Guerri,J M Sánchez-Vizcaíno,M A Jiménez,P Gozalbes,D García-Párraga

doi:10.1038/s41598-021-00867-6

Abstract

Aggressive behavior of bottlenose dolphins (Tursiops truncatus) towards conspecifics is widely described, but they have also often been reported attacking and killing harbour porpoises (Phocoena phocoena) around the world. However, very few reports exist of aggressive interactions between bottlenose dolphins and other cetacean species. Here, we provide the first evidence that bottlenose dolphins in the western Mediterranean exhibit aggressive behavior towards both striped dolphins (Stenella coeruleoalba) and Risso’s dolphins (Grampus griseus). Necropsies and visual examination of stranded striped (14) and Risso’s (2) dolphins showed numerous lesions (external rake marks and different bone fractures or internal organ damage by blunt trauma). Indicatively, these lessons matched the inter-tooth distance and features of bottlenose dolphins. In all instances, these traumatic interactions were presumed to be the leading cause of the death. We discuss how habitat changes, dietary shifts, and/or human colonization of marine areas may be promoting these interactions.

Highlights

Aggressive behavior of bottlenose dolphins (Tursiops truncatus) towards conspecifics is widely described, but they have often been reported attacking and killing harbour porpoises (Phocoena phocoena) around the world
An often-reported example of aggressive interactions between cetaceans are the attacks on harbour porpoises (Phocoena phocoena) by bottlenose dolphins (Tursiops truncatus)
Barnet et al.[39] reported that aggression from bottlenose dolphins might have led to the death of at least one Risso’s dolphin (Grampus griseus), one long-finned pilot whale (Globicephala melas), one striped dolphin (Stenella coeruleoalba), and four short-beaked common dolphins (Delphinus delphis) on the southwest coast of England

Summary

Introduction

Aggressive behavior of bottlenose dolphins (Tursiops truncatus) towards conspecifics is widely described, but they have often been reported attacking and killing harbour porpoises (Phocoena phocoena) around the world. Necropsies and visual examination of stranded striped (14) and Risso’s (2) dolphins showed numerous lesions (external rake marks and different bone fractures or internal organ damage by blunt trauma) These lessons matched the inter-tooth distance and features of bottlenose dolphins. An often-reported example of aggressive interactions between cetaceans are the attacks on harbour porpoises (Phocoena phocoena) by bottlenose dolphins (Tursiops truncatus). Such incidents of aggression are reported relatively frequently from UK and western USA waters and occasionally Northwest Spain, and may often lead to mortalities[11,12,13,14,15,16,17]. Aggressive interactions with bottlenose dolphins were proposed as the leading cause of death

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