Abstract: The species in Hylobatidae are specialized arboreal primates that barely move on the ground in the wild. In the previous monitoring studies, no records of bipedal walking behavior of Hainan gibbon (Nomascus hainanus) were re ported. Here, we recorded seven cases of the bipedal walking behaviors of the Hainan gibbon using a combination meth od of infrared cameras and human tracking in Bawangling area of Hainan Tropical Rainforest National Park from Janu ary 2020 to August 2023. The background, duration and activities after each action are described in detail. The behaviors were classified into active bipedal walking and passive bipedal walking, the causes are analyzed, and the topographic fea tures of the possible bipedal walking location are proposed, and the key monitoring regions are delimited. This report can not only protect the Hainan gibbon population more effectively but also provide updated data for compiling the be havior spectrum of Hainan gibbon.

Key words: Hainan gibbons (Nomascus hainanus), Bipedal walking behavior, Protection

关键词: 海南长臂猿, 下地行为, 保护