Seasonal movements and metapopulation structure of the Australian fairy tern in Western Australia

Abstract

The Australian fairy tern metapopulation in Western Australian is distributed over an extensive stretch of coastline (≤2500km). Using mark–recapture and coordinated community-based resightings of marked birds, this study reveals important insights into the seasonal movement, interchange and key locations used by Australian fairy terns. The Western Australian metapopulation consists of a widely distributed, partially migratory spring/summer-breeding population and a smaller, winter-breeding, sedentary population on the Pilbara coast. The spring/summer-breeding population winters, primarily, around the northern islands of the Houtman Abrolhos, before migrating to breeding areas as far south as Point Malcolm on the eastern south coast and as far north as the Ningaloo coast (Exmouth). Thus, in Western Australia, Australian fairy terns from the same population reproduce in both tropical and temperate marine regions. Associations between birds, persisting over multiple seasons, suggest that group adherence may be an important behavioural trait of these small terns. Based on the recent use of breeding sites and the likely spatial extent of exchange of breeding adults and natal recruits, seven ‘neighbourhoods’ are proposed, which likely represent the best units to underpin a conservation strategy for this threatened coastal seabird. The combination of small population size, strong area fidelity and the potential for strong group adherence among individuals are important considerations for the development of effective conservation strategies in Western Australia. Maintaining the Australian fairy tern population size within the suggested management units is critical for the long-term conservation of this species.