Sex predicts response to novelty and problem-solving in a wild bird with female-biased sexual dimorphism.

A wide range of animals, including a number of bird, fish, mammal and reptile species, show sex differences in cognitive tests. Hardly anything is known, however, about whether and how sex-specific non-cognitive factors (e.g. response to novelty) affect the expression of cognition in the wild. We used a series of learning and problem-solving tasks in wild breeding skuas, a species in which females are the larger sex (female-biased sexual size dimorphism). We also evaluated the birds' response to novelty (novel objects) before and after the tasks were administered. Both sexes performed equally well in learning () and re-learning () food associations with colour and spatial cues, but female skuas outperformed males in problem-solving tasks (, ). Females were also less neophobic than males: they were faster at accepting a food reward in novel situations. Better female performance may not imply higher cognition . Sex-specific size differences may translate into less or more neophobic behavioural types, which, in turn, predict females' problem-solving success and response to novelty. Species with female-biased sexual dimorphism may present a useful model to assess the interactions between sex, non-cognitive factors and cognition in the wild.