An Observation of Coordinated Collaboration in Wild Brown Skua (Stercorarius antarcticus).

Examples of non-human animals cooperatively problem-solving during foraging are rare in the natural world. However, early reports on Stercorariidae species describe mutualistic collaboration in which pairs of birds apparently coordinate to remove meat from animal carcasses. For the first time, we provide video evidence of this behaviour in brown skua (Stercorarius antarcticus) on the Antarctic Peninsula and analyse it against four categories of collaboration described in the literature. We observe that this feeding behaviour does have characteristics of some of the dependent measures required for actively coordinated collaboration. Skua were coordinating their actions over space and time, including appearing to wait for partners when working together and using a different feeding technique when the partner was unavailable. Skua held the carcass without shaking when waiting for the collaborator, and then repeatedly pulled in unison. By contrast, they shook or pecked the carcass when alone. Experimental studies are now needed to determine the extent to which skua understand the causal role of their partner. The behaviour we analyse is noteworthy, not only for its apparent rarity in wild animals, but because it provides a real-world example of the task captive animals are trained to undertake in classic cooperation experiments (coordinated pulling to obtain a food reward). We highlight Stercorariidae species as promising models for future research on avian social cognition and identify potential research questions that would help uncover both the ultimate and proximate mechanisms driving their collaborative behaviour.