Spatial structure in a Sichuan golden snub-nosed monkey Rhinopithecus roxellana group in Qinling Mountains while being in no-locomotion

Based on the identification of each individual,spatial structure of a provisioned group of golden snub-nosed monkey Rhinopithecus roxellana was conducted by instantaneous and scan samplings and all occurrence sampling.We found that the fundamental unit of spatial structure in the monkey group was their social units.Using spatial distance as the judgment of social unit,we found that individuals from the same social unit flock in the same tree or two adjacent trees with high frequencies 60.6% and 29.1% respectively when they are in no-locomotion.The spatial distances between individuals range from 0 to 10 m while their main distribution ranges form 0 to 5 m,which displays a frequency downtrend with the growth of distance.However,we also found that the spatial distances between individuals from different social units mainly range from 10 to 30 m,with the peak between 20 and 25 m,considerably longer than those between individuals from the same social unit.Thus,this research finding could provide a method for the judgment of one-male unit for future surveys of wild Rhinopithecus roxellana.When the monkeys were resting and foraging,the spatial pattern of the group had the appearance of either a circle or an oval.The social units were assigned to one of four concentric circles(layers)that were used to distinguish their relative spatial orientation.The statistics showed that the higher-ranking social units always appeared in the two most central layers(df=1,χ~2=166.97,P0.005).Lower ranking social units appeared most frequently in the outer most layer(df=1,χ~2=12.60,P0.005)and middle ranking units usually located in the middle layers(df=1,χ~2=21.54,P0.005).Higher-ranking units occupied larger and higher quality space.As the rank order of the social unit decreased,the quality and size of the space occupied also decreased.The characteristic shape of the group during movement was fluid.The monkeys’ spatial structure was closely related to their socio-ecological constraints,such as foraging and mating strategies,and predator avoidance