DO RINGTAILED LEMURS EXHIBIT A SKEWED BIRTH SEX RATIO DEPENDING ON SOCIAL AND ENVIRONMENTAL CONDITIONS? A PRELIMINARY ANALYSIS OF A WILD POPULATION

In a 13-year study, we examined the birth sex ratio (BSR) of wild ringtailed lemurs at Berenty Reserve in Madagascar. Their BSR represented an equal sex ratio at the population level, irrespective of population change. High-ranking females did not always overproduce sons or daughters. In newly formed groups, females did not always overproduce daughters, and the BSR of young females was similar to an equal sex ratio. Thus, our data do not support the Trivers-Willard, local resource competition-population, or local resource enhancement hypotheses. Only one significant skewed BSR was observed: low-ranking females in medium-sized groups overproduced sons. This finding may support the local resource competition-individual hypothesis, but does not do so robustly.