Many animals show sexually divergent foraging behaviours reflecting different physiological constraints or energetic needs. We used a bioenergetics approach to examine sex differences in foraging behaviour of the sexually monomorphic northern gannet. We used the relationship between dynamic body acceleration and energy expenditure to investigate energetic cost of prey capture attempts (plunge dives). Fourteen gannets were tracked using GPS, TDR, and accelerometers. All plunge dives in a foraging trip represented <4% of total energy expenditure,...