From May to October 2016,we conducted a survey on the population size and distribution of Sichuan snubnosed monkeys(Rhinopithecus roxellana) in Louguantai Experimental Forest Farm(43 026 hm2) located on the northern slope of Mt.Qinling in Shaanxi province.And then the social structure was analyzed.By using a V-shaped transects for the survey and long-term monitoring of infrared cameras,the monkeys were encountered 2 times at 2 different sites and the individuals of each group were counted:one was 65 individ...