Observation of offspring sex ratio in quenda, Isoodon fusciventer

Sex ratios in wild populations of mammals often differ from parity. Here, we describe variation in offspring sex ratios in a population of quenda (Isoodon fusciventer, Marsupialia: Peramelidae), along with observations of maternal body mass and home range size. We evaluate whether the Local Resource Competition (LRC) or Trivers-Willard hypothesis best explains the observed patterns in offspring sex ratio. During the study period, young (small) females over-produced sons, whereas older (larger) females tended to produce more daughters, providing evidence consistent with the LRC hypothesis in this species. There were, however, observed shifts in adult sex ratios compared to previous years. We further discuss the possibility of adaptive sex-ratio adjustment by female quenda to reduce competition with their kin.