A rare observation of group prey processing in wild leopard seals (Hydrurga leptonyx)

Abstract

Cooperative feeding is often observed among predators with strong social bonds; however, it is unexpected in solitary predators. During 2016, several mass predation events were witnessed in St Andrews Bay and Right Whale Bay, South Georgia, where up to 36 leopard seals (Hydrurga leptonyx) were seen feeding together at king penguin (Aptenodytes patagonicus) colonies. Three post-mortem prey-processing events were observed where two leopard seals actively fed on the same carcass in an unusual display of tolerance for a species where anti-social behaviour is the norm. The seals were observed repeatedly tearing adult king penguins between themselves, while floating alongside each other at the surface of the water. This is the first record of co-feeding in this difficult-to-study species; however, it is expected that the behaviour is rare within the population. We propose that the high density of predators combined with the readily available prey, makes it costlier to defend a kill than it is to tolerate kleptoparasitism. It is unclear whether this behaviour shows cooperative feeding, which would likely enable more efficient prey processing: by holding the prey in their jaws, each seal provides an anchor on the prey that others can pull against to stretch and tear it.