Golden snub-nosed monkey
Rhinopithecus roxellana

SOCIAL ORGANIZATION AND BEHAVIOR

Golden snub-nosed monkeys are usually considered to have two tiers of social organization with smaller social groups almost always conglomerating into well-organized larger troops, which can contain up to several hundred individuals and as many as 600 (Hu et al. 1980 cited in Kirkpatrick et al. 1999; Poirier & Hu 1983; Kirkpatrick 1995; Ren et al. 1998; Kirkpatrick et al. 1999; Ren et al. 2000; Zhang et al. 2006; Tan et al 2007). Some researchers, however, divide golden snub-nosed monkey social organization into three tiers; the basic social units, several basic social units organized into bands, and several bands organized into large troops while others place organization at just two levels, the smaller unit and the larger troop composed of the smaller units (Ren et al. 2000; Su et al. 2002; Tan et al. 2003).

Such aggregations of smaller social units into troops seasonally fluctuate, breaking up and aggregating at different times of the year, possibly due to human disturbance, thermoregulation, movement in snow, and availability of food items (Kirkpatrick 1995). Some researchers suggest that there is a fission-fusion social system within the troop while other researchers suggest that troops are stable and do not fluctuate in size (Ren et al. 2000; Tan et al. 2003). The basic social groups are of two types, the multi-female one-male unit (OMU) (possibly the primary social unit) and the all-male unit (AMU) (Ren et al. 1998; Ren et al. 2000; Zhang et al. 2006; Tan et al. 2007). OMUs average 9-18 individuals while all-male units average 4-7 individuals (Ren et al. 1998; Ren et al. 2000; Zhang et al. 2006). OMUs usually have stable membership and consist of several females, one male, and immature individuals (Poirier & Hu 1983; Kirkpatrick et al. 1999; Ren et al. 2000; Zhang et al. 2006). The male is the highest-ranking monkey in the OMU, with females ranking second after the adult male, occupying an unstable hierarchy amongst themselves. Sub-adult and juvenile individuals occupy the lowest ranks within the OMU (Li et al. 2006). Within a larger troop, one-male units have a hierarchical organization, with some units dominant to others (Zhang et al. 2003; Li et al. 2006). In addition, OMUs normally have one adult male but it is possible to have more than one (Ren et al. 2000; Zhang et al. 2006).

AMUs can contain 3-6 males but are not present in all instances (Kirkpatrick et al. 1999; Ren et al. 2000; see Wang et al. 2004). At one study site, the large troop consisted of adult males (10.5%), adult females (29.7%), sub-adult males (6.9%), adolescents (26.3%), juveniles (12.5%) and infants (14%) (Ren et al. 2000). When the troop is at rest or feeding, juveniles and infants will aggregate into groups that can be larger than 40 individuals (Ren et al. 1998). Homosexual mounting during play occurs between juvenile males and might function in social bonding (Lu et al. 2007).

When moving as a group, males buffer both ends of the troop with OMUs at the middle. As such, males act as a vanguard and rearguard for the group while traveling (Yan et al. 1995; Ren et al. 1998; Ren et al. 2000). The pattern is similar during foraging with males distributed at the front, center, and back of the troop with both females and infants more towards the center of the troop. Sub-adult males are mostly found at the center and back of the troop (Zhang et al. 1999c). When a threat is perceived in the environment, dozens of group males will aggregate, display, and vocalize in the direction of the threat (Ren et al. 2000).

There is a dominance hierarchy among both males and females in a smaller social unit (Ren et al. 1990b; 2000; Tan et al. 2003). Within an OMU the male and females won't interact aggressively but adult females will fight with one another, with sub-adults, and with the young (Ren et al. 2000). In addition, in conflicts between females, males will intervene and help to pacify the females (Ren et al. 1991). In captivity, females within a unit can be dominant to the male (Ren et al. 1990b cited in Ren et al. 2000).

Grooming most often occurs within the same unit (92.4%) and only rarely with individuals in other units in the troop (Zhang et al. 2006). More intense and faster grooming is used to reconcile after a conflict (Ren et al. 2000). Allogrooming frequencies are influenced by social ranking and the primary motivation for grooming is hygiene (Li et al. 2002b).

In captivity, types of aggression include threats, chases, hitting, and biting. Post-conflict interactions include open mouth, rapid grooming, embrace and crouching behaviors (Ren et al. 1991). In the wild, males often aggressively interact with one another and generally do not accept the presence of other males when near females (R.M.Ren pers. comm. cited in Grüter & Zinner 2004; Grüter & Zinner 2004). Takeover of a OMU occurs when either a single male or the members of an AMU invade and oust the resident male using threats, displays, fighting and chasing; the outcome of which is possibly at least partially due to female preference (Guo pers. comm. cited in Wang et al. 2004; Wang et al. 2004). In addition, aggression between OMUs is quite common and occurs on average of 11 times per day (Tan et al. 2003).

Males leave their natal OMU when they are forced out at 3 years old by their father while most females seem to stay in their natal OMU (Ren et al. 2000).

REPRODUCTION

The wild golden snub-nosed monkey has a polygynous mating system in which a male in a OMU can mate exclusively with the adult females within his group (Li & Zhao 2007). However, extra-unit copulations are known in wild populations, albeit rare (Zhao et al. 2005). Breeding is seasonal in the wild in the Qinling Mountains, with copulations most frequent between September and November, peaking in November with a corresponding birth season between March and May, peaking in April (Li & Zhao 2007). Females avoid mating competition by staggering conception times (Ren et al. 2003). In captivity, birth seasonality is also observed but varies with the location of the captive population (Poirier & Hu 1983; Ren et al. 1995; Zhang et al. 2000; Ren et al. 2003). It is suggested that the seasonality of reproduction is timed such that births occur during favorable environmental conditions most conducive for the survival of the infant (Zhang et al. 2000). In captivity, in spite of seasonal breeding, some mating behavior occurs throughout the year (Ren et al. 1995).

In both the wild and captivity, it is primarily females who initiate copulation, although males will do so rarely (Ren et al. 1995; Liang et al. 2000; Ren et al. 2003; Zhao et al. 2005; Li & Zhao 2007). The typical solicitation posture of females in both the wild and captivity is the "prostration" posture. First, the female will look at the male, run a small distance and then lay with her head down and arms outstretched with her legs curled up and her buttocks exposed (Qi 1986; Ren et al. 1995; Zhao et al. 2005; Li & Zhao 2007). In the wild, a second type of female courtship is observed in which the female will perform a chest curl with a lowered head and show her back to the male without exposing her buttocks (Li & Zhao 2007). In rare instances of male solicitation, they may use "open mouth" solicitation gestures, female pattern "prostration" postures, "stare courtship," or "approach courtship" behaviors (Ren et al. 1995; Li & Zhao 2007). In the wild, copulation consists of the male mounting the female from behind and grasping both ankles and lasts an average of 16 seconds. After copulation the pair will groom, huddle, or move away from one another (Li & Zhao 2007).

In the wild, both sub-adult and adult females will attempt to disrupt copulation between a male and another female by vocalizing, physically contacting the pair and interfering prior to and during copulation (Li & Zhao 2007).

In captivity, females generally start soliciting and mating at around 3 years of age, although first births occur at around 5. Males first copulate at around 4 but usually don't impregnate females until 6.5 years old and may not successfully reproduce until 7-8 years old (Liang et al. 2000; 2001). The appearance and development of the upper-lip warts in males is generally considered to be an indicator of sexual maturity (Liang et al. 2002).

The average estrous cycle lasts 27-29 days and is longer in the non-reproductive season (Gao & Liu 1995; Hama et al. 1995). Observed captive gestation lengths range between 174 to 208 days (5.7-6.8 months) and in the wild, this range seems roughly accurate as gestation is estimated at 6 months (Rapaport & Mellen 1990; Hama et al. 1995; Yan et al. 2003; Li & Zhao 2007). Interbirth interval is 18-20 months (Ren et al. 2003).

PARENTAL CARE

Birth in captivity usually occurs at night and the natal coat consists of long black hairs on the back and head with the rest of the body including the ventral areas covered with white-grey hair (Qi 1986; Rapaport & Mellen 1990). Golden hairs start to appear on the cheeks and arms at 9 days old but by three weeks of age, there is still dark gray hair in the pelage. The skin around the mouth and the palms and fingers is pink at birth but this color fades in the first several weeks (Rapaport & Mellen 1990).

At birth in captivity, the newborn sleeps and feeds in its mother's arms. At about two weeks old, it will become more independent, eating and playing near its mother (Qi 1986). In the wild, infants are first seen separate from their mother at 23 days old and begin exploratory play at 68 days old. Social play starts at around 2-3 months and increases through 7 months old, with infants preferring to play with other infants of similar age (Li et al. 2004). Solid food is consumed in the wild at 5 months old and infants travel with the group at 6 months old. Infants can be found in contact with caregivers for the first year, however as the infant ages, the amount of contact is less and less and independence increases (Li et al. 2005). Infants are allomothered by other females within their natal OMU and are protected by all group members of both sexes (Poirier & Hu 1983; Su et al. 1992; Su & Ren 1992). Other female unit members will snatch or kidnap, protect and care for the offspring of other females in their OMU. Males have affinitive and tolerant relationships with infants, however they will not typically carry infants (Su et al. 1992; Su & Ren 1992; Su et al. 1992 cited in Ren et al. 2000; R. M. Ren pers. comm. cited in Grüter & Zinner 2004). Weaning conflict starts between an infant and its mother around a year of age and complete weaning occurs around the 19th and 20th month (Su et al. 1992; Su & Ren 1992; Su et al. 1992 cited in Ren et al. 2000).

During periods of group rest, aggregations of up to 60 juveniles attended to by one or several males are reported in wild populations, coming together for play or exploration (Ren et al. 2000). Due to the large numbers of juveniles involved, such gatherings must involve the young from different OMUs (Grütter & Zinner 2004).

Infanticide by adult males has been reported in captive golden snub-nosed monkeys (Zhang et al. 1999a).

COMMUNICATION

Vocal communication in the golden snub-nosed monkey is marked by the species' ability to vocalize in a ventriloquial manner, meaning that they are capable of vocalizing without any visible sign that they are doing so. This is possibly due to their large nostrils. However, they also often vocalize with corresponding mouth and facial movements as well (Tenaza et al. 1988; Clarke 1990; Li et al. 1993). Vocal communication in the wild stabilizes the population by leading troop activity, maintaining group order, and reducing the energy expenditure of group members (Li et al. 1993; Li & Yang 1994).

There are 18 different types of vocalization reported for the species in the wild (Ren et al. 2000). In the wild, six general categories of vocalization are described, amazement calls, alarm calls, warning calls, peaceful calls, contacting calls, and other vocalizations (including whines, chucks, hoos, belches, and moans). Amazement calls are uttered when the monkeys meet other animals. Alarm calls are heard when approached by strangers (Li et al 1993). There are five general types of alarm calls; astonishing calls, light alarm calls, alarm calls, frightened alarm calls, and directional alarm calls (Ren et al. 2000). Warning calls are used to threaten subordinates and peaceful calls are heard during moving, eating, playing and resting. Contacting calls are used when meeting strangers and coalescing groups into larger troops. Other types of vocalizations are only heard rarely (Li et al 1993). There are five types of affinitive vocalizations, as well as aggressive vocalizations used between adults, and calls used by females and their offspring when separated (Ren et al. 2000).

In captivity, both sexes produce all types of vocalizations, but there are significant differences by sex in the production of several types (Tenaza et al. 1988). Finally, it is important to note that the majority of vocalizations are highly variable and often grade into one another (Tenaza et al. 1988).

In captivity, vocal exchanges occur in which one animal vocalizes and another immediately responds (Tenaza et al. 1988; Clarke 1990). This calling and responding in captivity between pairs may be similar to choruses of several individuals in the wild emitting calls together for several seconds at a time (Tenaza et al. 1988). In the wild, males participate in call and respond vocalizations with other males, termed "hello-respond" interactions. In addition, families will chorus while the group is at rest, using several different calls (Ren et al. 2000).

In captivity, social communication by postures and facial expressions is divided into aggressive, display, submissive and friendly behaviors, including 17 social repertoires (Ren et al. 1990a). Threats are communicated in the golden snub-nosed monkey by a closed mouth, staring, and pointing the head at the adversary. To make the threat stronger, vocalizations are added and the shoulders are shrugged (Ren et al. 2000). In the wild, displays function to not only to show the monkey's strength and power, but also to conduct or urge the group to move (Ren et al. 2000). Submission is shown by crouching. Affinitive feelings are indicated by the "open mouth" gesture. This "open mouth" gesture is used by adult males in conjunction with a raised head and a stare in the "waiting for" behavior which serves to communicate encouragement to overcome travel difficulties (Ren et al. 2000). Fifty-four behavioral repertoires and action patterns of the golden snub-nosed monkey are recognized. Eight social behavioral repertoires and action patterns are observed only in golden snub-nosed monkeys or are only rarely observed in other primates (Yan et al. 2006).

Although unstudied, the upper-lip wart-like growth in adult males might produce secretions which could potentially serve a communicatory purpose (Liang et al. 2000).

Content last modified: November 20, 2007

Written by Kurt Gron. Reviewed by Renmei Ren.

Cite this page as:
Gron KJ. 2007 November 20. Primate Factsheets: Golden snub-nosed monkey (Rhinopithecus roxellana) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/golden_snub-nosed_monkey/behav>. Accessed 2013 May 26.