LAUSR

Abstract We presented the result of a systematic survey on the population size and distribution of the Endangered Gaoligong hoolock gibbon (Hoolock tianxing) in Houqiao Town, Tengchong City, Yunnan Province of China. A total of 15–18 individuals of H. tianxing in 5–6 gibbon groups and one solitary gibbon were recorded during the survey conducted in November 2019. The mean group size was 2.8 individuals (range 2–4) with a population density of 0.32–0.39 groups/km2. All groups contained an adult pair, and one or two immatures were observed in all but two. Mean dawn time was 07:21 h during the survey, and most vocalizations were produced between 1.0 and 2.5 h after dawn (75% of total song bouts), with an average song bout duration of 22.5 min (n = 12). Our result revealed that the Houqiao subpopulation of H. tianxing is of high conservation significance, since it is one of the largest subpopulations for the species in China and occurs in an unprotected area. The Houqiao forest is subjected to frequent human disturbance and the thriving agroforestry activity is degrading the forest integrity. Immediate conservation interventions are needed to safeguard the future of this important gibbon subpopulation. Discussions on the major threats to the species and relevant conservation recommendations are provided.