Social Correlates of Variation in Urinary Cortisol in Wild Male Bonobos (Pan paniscus)
Cortisol excretion in males of group living species is often associated with social rank and competition for oestrous females. Rank-related patterns of cortisol levels can be used to study mechanisms of rank maintenance and costs associated with mate competition. Bonobos (Pan paniscus) are interesting because males form a linear dominance hierarchy but are not dominant […]
Behavioural responses to season and adult sex ratio in the fantail darter Etheostoma flabellare
Social behaviours such as competition for mates, which can indicate the strength and direction of sexual selection, may change either directly or indirectly in response to the operational sex ratio (OSR). Field studies indicate flexibility in social behaviours in response to a changing OSR, in particular as the OSR changes across the breeding season. Remaining […]
Competitor size, male mating success and mate choice in eastern mosquitofish, Gambusia holbrooki
Males usually compete for mates but, by choosing a favourable social environment (e.g. avoiding stronger competitors), males might increase their reproductive success. We first tested whether the mate choice of male eastern mosquitofish depended on the size of potential competitors. In two-choice trials, focal males preferred to associate with a group of large males over […]