Dominance Hierarchy And Affinitive Behavior Of The Fran(?)ois' Langur In Captivity

Data on social behaviors were collected from three groups of Fran?ois'langur (Trachypithecus francoisi) in captivity at the Primate Reproductive Center, Nanning Zoo, Guangxi, between July 2007 and November 2008 using Focal Animal Sampling, Behavior Sampling and Continuous Recording. A total of 14,902 social behaviors were collected. The main object is to explore the characters of social structure in Fran?ois'langur, as well as the factors influencing their social structure.The results indicated that:(1) In Fran?ois'langur groups, the affinitive behaviors were main types of social behavior, and occurred most frequently. However, the frequencies of aggression behaviors and display behaviors were lowest in the social behaviors. This indicates friendly social structure in Fran?ois'langur groups.(2) Based on date on the direction and frequency of conflict behavior and submissive behavior among individuals, the dominance index was calculated for each individual, and the dominance among individuals was ranked. The results indicated that: in cageâ… #, it was M1>F1>F3>F2; in cageâ…¢# , it was M3>F8>F9>F7; in cageâ…¦# , it was M2>F4>F5>F6. We documented a linear dominance ranking order existing in each one-male-unit, and adult males were dominant to adult females. Among adult females, high-ranking individuals initiated aggression behavior more frequently than the low-ranking individuals. Moreover, they also received more submissive behaviors.(3) There were significant variations in initiation and acceptance of affinitive behaviors among individuals. Except for F8, the frequency of affinitive behaviors decreased with the dominance. The allogrooming behaviors occurred most frequently in the affinitive behaviors. There was significant variations in the frequency of allogrooming behaviors among different individuals (X2 = 46.83, P <0.001; X2 = 124.609, P <0.001; X2 = 355.059, P <0.001). Allogrooming behaviors occurred more frequently between adult females than between adult males and females. We suggest that in Fran?ois'langur group, allogrooming serves not only hygienic function, but also a number of social functions, such as mitigating the tension between individuals and establishing union. Moreover, allogrooming is an expression of mutual attraction.