Abstract: Primates are important vectors for seed dispersal in forest ecosystems. Foraging behavior and habitat use by primates could determine their contribution to the effectiveness of seed dispersal and forest regeneration. Hoolock tianxing is a flag species in Gaoligongshan, Yunnan, China. Information on fruit use and seed dispersal is needed to understand the role ofH. tianxingas a potential seed disperser and its contribution to forest regeneration. In this study, we investigated fruit food and seed dispersal by a family group of H. tianxingfrom October 2017 to December 2018. The results showed that H. tianxing foraged fruits from 33 species belonging to 26 genera, 21 families. Foraging frequency of fruits by H. tianxing varied among four seasons, with the highest foraging frequency in the autumn (from September to November). Fruit traits were the most important in affecting food use by H. tianxing. Small fleshedfruits and fruits with green or red color were preferred by H. tianxing. However, H. tianxing also feed on fruits with other colors during fruit-rich seasons. A total of 5099 intact seeds were found in 104 feces, with the density of Toddalia asiatica,Cayratia japonica,and Vaccinium mandarinorum seeds being significantly higher than that of other species. Our results indicated that H. tianxingplays an important role in seed dispersal for more than 10 plant species. Further studies should consider the role of H. tianxing in seed dispersal effectiveness and forest regeneration.

Key words: seed dispersal, Hoolock tianxing, fruit food, Gaoligongshan.