Vocal Communication Serves As Social Function In Golden Snub-Nosed Monkey(Rhinopithecus Roxellana)

Vocal signaling is most common behavior and plays an effective role in animal daily life.Animals maintain individual affiliation by vocal communication in species with complex social structure.Multilevel societies,the most complex social structure,occur in only a few primates,including the snub-nosed monkey(Rhinopithecus roxellana).Here we examined social affiliation in wild golden snub-nosed monkeys(Rhinopithecus roxellana),a species of nonhuman primate that forms a modular or multilevel society composed of several one-male harem units that aggregate to form a breeding band that can contain up to several hundred individuals.In this complex social structure,there are complex social connections between individual to maintain group stability,but the function between vocal communication and social affiliation remains unclear.The study was carried out in the northern slope of the Qinling Mountains in the village of Yuhuangmiao,in the Zhouzhi National Nature Reserve(ZNNR),Shaanxi Province,China from 22 September 2018 until 4 June 2019.We conduct a research on golden snub-nosed monkeys breeding band was composed of 16 OMUs to evaluate the social affiliation function of vocal communication.We used focal animal sampling and instantaneous scan sampling,used all-occurrence sampling method to record the behaviors of all individuals,including spatial proximity,grooming,aggressive-submissive behaviors and vocalization.Social network analysis(SNA)was used to conduct the association matrices based on spatial proximity,grooming and vocal communication.Quadratic Assignment Procedure(QAP)to analyze the affiliate relationship matrix,respectively.David's Score was used to calculate the dominance of each unit in the Breeding band.SPSS V24.0 was used to compare the differences in voice communication among individuals.The results showed that individual form social bonds with another individual from else OMU by vocal communication within the breeding band.Quadratic Assignment Procedure(QAP)correlation analysis reveals that vocal communication was significantly correlated with spatial proximity,but shows no correlation with grooming in units.Among OMUs in the GNG-Breeding band,we calculated a linear hierarchical dominance relationship,and result show that the individuals with a higher position in the dominance also have the lead in the vocal communication.Males vocalized more than did females in each unit,and almost twice that of female-initiated vocal communication.The results indicated that resident males have selective vocal communication with females who has infant(infants less than 12 months old).Given that no affiliation behavior except for vocal communication can be found among units in golden snub-nosed monkeys,vocal communication may serve as a critical function in affiliating different units.Our results might provide new evidence for the co-evolutionary relationship between diverse behavior pattern and complex social systems.