Co-occurring species sharing a limited resource are thought to adopt alternative strategies to coexist. Here, we investigate four species of co-occurring albatrosses in southern New Zealand that share food resources but differ in dominance status to test for variation in strategies to acquire supplemental food provided by ecotourism boats. We found evidence for distinct foraging strategies consistent with each species’ dominance rank. Buller’s albatross (Thalassarche bulleri) was the most subordinate species and frequently pursued scraps of fish on the periphery of the feeding flocks and avoided interacting with other species. Salvin’s albatross (Thalassarche salvini) and White-capped albatross (Thalassarche cauta) were intermediate in dominance status; both had fast responses to food and typically pursued the main food source, though T. cauta successfully stole fish while T. salvini did not. In contrast, Southern Royal albatross (Diomedea epomophora) was the dominant species and did not avoid interactions with other species and pursued the main food source but was slower to respond compared with some subordinates. Natural food sources mirror the scenarios seen behind ecotourism boats, suggesting that differences in foraging strategies are likely present without human intervention. Overall, our results suggest that foraging strategies associated with dominance hierarchies could help structure seabird communities.
Allen Keast International Exchange Fund
Erskine Visiting Fellowship from the University of Canterbury (Christchurch)