The dispersal and migration of the Northern Gannet Morus bassanus from Channel Islands breeding colonies

Abstract

Around 7,500 pairs of Northern Gannets Morus bassanus nest at two long- established gannetries off Alderney, Channel Islands, the second and third most southerly colonies in the world. This paper describes the temporal and spatial distri- bution within five geographic zones of recoveries of birds ringed as chicks at these colonies. First-year birds migrate south in autumn earlier than those from gannetries further north, many to waters off northwest Africa and some as far south as Senegal, while others move into Mediterranean Waters, perhaps more readily than juveniles from more northern colonies. Some remain in southern latitudes during their second summer but most have returned at least into West European Waters. After their second winter, immature birds tend to summer in Northern Waters, with recoveries often in the vicinity of different gannetries. Most Channel Islands birds probably recruit into their natal colonies, but some have recruited into more recently established gannetries, on Helgoland, Germany and Gjesvær, Finnmark, Norway. Recoveries of adults were mainly from Northern Waters, but also along the coasts of the Bay of Biscay and Atlantic Iberia, at all times of year.