Bottlenose dolphin predation on flathead grey mullets using barrier feeding techniques: a visual and acoustic case study in the Mediterranean Sea

We report first-time evidence of barrier feeding techniques in the population of common bottlenose dolphin (Tursiops truncatus) at the estuary of the Tiber River (Rome, Italy), used to prey on the flathead grey mullet (Mugil cephalus). We describe an event that occurred in summer 2023, consisting of dolphins forcing schools of mullets against different types of barriers, i.e. sea surface, coastal breakwater blocks and other dolphins. We provide the first visual and acoustic account of this predation modality in the Mediterranean Sea, showing that bottlenose dolphins adopted techniques to fragmentate prey assemblages and then to limit prey escape routes by forcing them against barriers. In this way dolphins were able to catch the mullets both in air and in the water. Such a technique possibly depends on the ability of sensing each other in the hunting group and of exchanging information through different types of vocalizations.