Orca (Orcinus orca) prey-handling and harassment of southern right whales (Eubalaena australis) in Península Valdés, Argentina

We report the first video-documented case of orca ( Orcinus orca ) cooperative prey-handling and feeding behavior on a southern right whale (SRW, Eubalaena australis ) calf carcass, along with harassment events and whale responses, recorded in the Natural Protected Area El Doradillo in Península Valdés, Argentina. Drone footage and shore-based observations were conducted on September 5, 2025, revealing an orca group refloating and feeding on a sunken whale calf carcass. The orca group consisted of six identified individuals from the Península Valdés population. Drone footage (total recording time: 1 h 37 min) showed coordinated behavior among orcas, who alternated in holding, lifting, and releasing the carcass, suggesting cooperative handling. The orcas engaged in forty-six harassment events targeting southern right whales, especially mother–calf pairs. Defensive responses described as 360° turns and zigzag pattern were elicited more often when orcas approached from the latero-caudal angle with respect to SRW head. These results expand the knowledge on the behavioral ecology of this orca population and underscore the ecological significance of orca–right whale interactions in one of the most important SRW breeding grounds in the Southwestern Atlantic Ocean.