Postmortem Attentive Behaviour in Indian Ocean Humpback Dolphins (Sousa plumbea)

Postmortem attentive behaviour (PAB) has been recorded across several mammalian species. Here, we document two instances of PAB in the Indian Ocean humpback dolphin (Sousa plumbea) along the Sindhudurg coast in Maharashtra, India. We describe the subsequent behaviours displayed by the care-giving individuals and other group members. In both cases, an adult ‘postmortem attender’, was observed to support and erratically move around a dead calf. In the second case, the adult–calf pair was escorted by a second adult individual. An examination of the carcass in the first instance revealed blunt force trauma under the right flipper of the calf. These findings suggest that closely associated group members may be distressed by injury to or death of an offspring and stress the importance of long-term behavioural studies. We also discuss the evolutionary significance of PAB in the larger context of social behaviour across mammalian groups and the importance of cataloguing these incidents.