Yun Nan Wuliangshan Indo-Chinese Gray Langur Social Structure And Fission-fuison

Social organization and social structure respond to strategies by social primates to adapt specific habitats.Compared to other primates taxons,Asian colobines showed a high degree of diversity in the social organization.The diversities occur bothinterspecies and intraspecies.thereby provide the opportunities to explore the ecological factors with the limitation on phylogenetic effects.Indo-Chinese gray langur(Trachypithecus crepusculus,Colobinae,Cercopithecidae,Primates)is distributed in northeastern and central Thailand,northern Vietnam,eastern and southwestern Laos and Wuliangshan,Ailaoshan which is located southwestern China along the eastern bank of the Salween River and Xishuangbanna,Nangunhe Huanglianshan and other regions in China.Indo-Chinese gray langur manifested a remarkable flexibility in the social organization: southern populations formed small groups with less than 20 individuals in each group,similar to other Asia langur,while northern peripheral population could form large groups with more than 100 individuals.During this study,a northern large group even showed fission-fusion phenomenon.These phenomena help us to understand the influence of ecological factors on the social organization.To better understand Wuliangshan Indo-Chinese gray langur social organization and social structure,from May 2010 to April 2016,we conducted a study on the social organization and fission-fusion events of a habituated group of Indo-Chinese gray langur at Dazhaizi in the Mountain Wuliang,Jingdong,Yunnan,China.we aimed at,s(which has been habituation)We also monitored the dynamics of the langur's diet,activity time budget with 10 min interval scan sampling,and daily path length and home range with 30 min GPS location.In order to reveal the social structure,we recorded the number of individuals in different age and gender within 5 m radius of focus adult males.The results showed: from the beginning of May 2010,a group of gray langur in Dazhaizi was increasing(80 individual),and the group increased to about 120 individuals in 2014,and dividied into two sub-groups(group A with about 80 individuals and group B with about 50 individuals).In April,September and November 2015,two subgroups combined temporary.During the three years before group fission,148 plant species belong to 57 families was recorded consumed by langurs feeding 27 ± 8 kinds of species per month,food species contributed >1% of the annual diet consumed of Indo-Chinese gray langur are 24,24,29 at three years before fission group;after fission group was recorded feeding 49 families and 104 species of plants,feeding 20 ±15 kinds of species per month,group A.food species contributed >1% of the annual diet consumed of Indo-Chinese gray langur are 22 There was no significant difference in the monthly fooddiversity before and after fission group.Before and after fission group,Indo-Chinese gray langur exhibits differences on the food composition: Compared with before fission group,group A feeding proportion of fruits,seeds,flowers and soil risen;feeding proportion of leaves and buds,old leaves decline.Every year Indo-Chinese gray langur were mainly feeding on young leaves and buds in February to May were mainly feeding on mature leaves in May to September,were mainly feeding on fruits and seeds in September to December.After fission group,Indo-Chinese gray langur improve the time of traveling and feeding,reduced the time of resting and social behavior.This difference is more obvious when Indo-Chinese gray langur were mainly feeding on fruit and seeds,and not obvious when Indo-Chinese gray langur were mainly feeding on young leaves and buds.Indo-Chinese gray langur traveling slightly shorter in daily path length after fission group,but the difference was not significant compared with before fission group.In the month prior to feeding fruits and seeds and feeding young,leaves and buds of the month Indo-Chinese gray langur daily path length also have no significant difference among fission group.Moreover,the gray langur home range is significantly smaller after fission group: the home range is 446 ha before fission group,the home range of group A is 239 ha,the home range of group B is 276 ha,there are large areas of overlapa with two groups home range.When the polymerization two subgroups of temporary area is 183 ha.We collected 1588 times accurately identify valid data with the number of individuals in different age and gender in the focus adult male with the scope of 5 m.(at least one other individual).Among them,the probability of other adult males was 42.1%around the focus adult male,the number was 0.55 ± 0.79 individual;while the probability with appeared simultaneously adult male and adult female is 31.5%.When on feeding,he probability of other adult males around the focus adult male(47.1%)and the number(average 0.71)which are greater than on resting and traveling,the maximum number is five adult male.Our results suggested that the study group did not live in multi-level society that composed of several one-male units and all male units,but live in multimale-multifemale group.Our results also demonstrated that tolerance between adult males in this group was high,especially during feeding.Up to 18 individuals feeding within 5 m to the focal male suggested that food resources were abundant in Wuliang Mountain,at least during certain seasons,which partly explained why Indochinese gray langurs could live in such large groups in the area.