Ecological adaptations of moult in some British gulls

Abstract

The moult sequences of the Herring, Great and Lesser Black-backed Gulls are similar. All three commence their complete moult towards the end of the breeding cycle which means that Lesser Black-backed Gulls moult later than the two other species. Rarely, late nesting gulls start primary moult during incubation. The complete moult takes about four months. Unlike the other species, the Lesser Black-backed Gull is a migrant and its wing moult occurs both on the breeding and wintering grounds, but birds may interrupt the moult so as to migrate without gaps in the wings. Adult gulls probably raise their young when food is most eastily obtained but they also need to be efficient in flight at this time, which might result in a delay to the onset of moult. Immatures are not under these pressures and replace their primaries during the time the adults are breeding. It is possible that this early moult makes breeding difficult for sexually mature, but immature plumaged gulls. © 1971 Taylor and Francis Group, LLC.