Variation in foraging strategies of New Zealand albatross species within a dominance hierarchy

Abstract

ABSTRACT 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 fish and typically pursued the largest fish scraps, 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 largest fish scraps but was slower to respond compared with some subordinates. Natural food sources approximate 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.