Behavioural Correlates of Female Social Status and Birth Mass of Male and Female Calves in Reindeer

In polygyny, male breeding success depends more than female success on body size, and male birth mass may therefore be more strongly correlated with mother's social dominance status. Among female reindeer, Rangifer tarandus , the rate at which a female took over winter feeding craters from conspecifics depended on rank and the mass loss decreased with increasing rank. Birth mass of male calves depended on mother's social rank, but that of female calves did not. Male foetuses appeared to be more effective than females to utilize resources associated with mother's phenotypical superiority.