Sexual conflict theory predicts that, in species with sexual reproduction, separate sexes and conventional sex roles, reproductive success (RS) of females depends mainly on resources and is largely independent of the number of males available, whereas RS of males mainly depends on mating opportunities and should increase with the availability of fertilizable females (Bateman, 1948;Clutton-Brock, 2009;LeBas, 2006;Trivers, 1972). Female availability depends on the operational sex ratio (OSR), that is, the ratio of sexually active males to receptive (fertilizable) females within the population (Emlen & Oring, 1977). However, increasing evidence is accumulating that mate limitation can increase competition for access to mates and negatively affect RS not only in males but also in females as well, in particular under female-biased sex ratios (Ah-