Meta-population evidence of oriented chain migration in northern gannets (Morus bassanus)



Although oriented migrations have been identified in many terrestrial bird species, the post-breeding-season movements of seabirds are generally regarded as dispersive. We used geolocator tags to reveal post-breeding movements and winter distribution of northern gannets (Morus bassanus) at a meta-population scale. By focusing on five breeding colonies of European gannets, we show that their breeding and wintering grounds are connected by a major flyway running along the coasts of Western Europe and Africa. Moreover, maximum winter distance to colony was similar across colonies despite their wide latitudinal range. In contrast with the general opinion that large pelagic birds such as gannets have unlimited ranges beyond the breeding season, our findings strongly suggest oriented chain migration in northern gannets (a pattern in which populations move uniformly southward) and highlight the benefit of meta-population approaches for studying seabird movements. We argue that the inclusion of such processes in ocean management plans is essential to improve efforts in marine biodiversity conservation.