Reproductive Parameters of Wild Female Hainan Gibbons (Nomascus hainanus): Implications for Conservation

As a Critically Endangered primate species endemic to China, the Hainan gibbon (Nomascus hainanus) represents a conservation priority requiring urgent research attention. A study of its reproductive parameters can provide a scientific basis for the population recovery of this species. From October 2010 to December 2025, we recorded information on female reproduction and infant survival of the Hainan gibbon populations through direct observation. Meanwhile, we also integrated previously published reproductive data from November 2002 to June 2013. Based on 48 births of gibbons, we quantitatively analyzed reproductive seasonality, infant mortality, and interbirth interval. The results showed that gibbons reproduce throughout the year, and most births occur from November to March. Four infant deaths (i.e., within the first 2 years of life) were recorded, accounting for 8% of the total births during the 15‑year study period. Infants of primiparous females had 50% mortality, whereas the infant mortality of multiparous females was only 3%. The average interbirth interval was 29 months. Infant death resulted in a shorter subsequent interbirth interval. The year-round breeding patterns and relatively short interbirth intervals in female gibbons indicate that the current population has a moderate reproductive potential. However, emergency plans should be formulated to address the risk of infant mortality in females' first reproduction, so as to maximize the survival rate of infants and facilitate the population recovery of Hainan gibbons.