Sex differences in foraging behaviour can arise in monomorphic species when reproductive roles differ. How these differences shape foraging behaviour during the pre-laying period—an understudied reproductive stage in seabirds—remains unclear. In a monomorphic procellariform seabird, the Manx shearwater ( Puffinus puffinus ), we compare foraging behaviour between sexes during pre- and post-laying periods. Prior to laying, sex r...