Recruitment to the breeding group in the Black-legged Kittiwake Rissa tridactyla

In their recent paper, Rothery, Harris, Wanless & Shaw (2000), Atlantic Seabirds 4: 17-28, use the assumption that the Black-legged Kittiwakes breeding on Fair Isle are an inbreeding, isolated group or population and that the recruits to this breeding group are all or mainly produced from within that small island. This assumption is almost certainly incorrect. While many Kittiwakes, particularly males, are philopatric and return to breed where they hatched, an appreciable proportion of both sexes move considerable distances and breed elsewhere (Coulson & Neve de Mevergnies 1992, Ardea 80:187-197). For example, at the study colony at North Shields, northeast England, two ringed breeding birds were reared in Norway, two hatched at Dunbar, east Scotland and several were from the Farne Islands, northeast England. Chicks from North Shields and the Farne Islands subsequently bred in Sweden, Helgoland, Scilly Isles, southwest England and France, and there are many other records of similar movements. At North Shields, fewer than 40% of the recruits to the breeding group were hatched there. In another colony being currently studied, philopatric breeding birds comprise fewer than 10% of the total number nesting. This dispersal behaviour is not restricted to the Kittiwake and similar patterns are known from studies on Larus gulls. This dispersal of young from the natal area is of great importance in developing management policies for colonies of large Larus gulls. It also moderates local, poor breeding performance.