Mother-Infant Interactions in a Wild Population of \u3ci\u3eMacaca nemestrina\u3c/i\u3e (Linnaeus)

Until now, mother-infant relationships have not been studied in a wild population of the Southern Pig-tailed Macaques Macaca nemestrina. We observed six mother-infant dyads from April 2016 to September 2016 in the Segari Melintang Forest Reserve, Peninsular Malaysia using focal sampling methods from the perspectives of both individuals. We hypothesized that as infant age increased, the same important mother-infant behaviours, previously observed to change in captive pig-tailed macaque mother-infant studies, would also change over time in field conditions. We expected that as the infant ages, mothers would decrease their rates of restraint and retrieval, and increase their rates of punishment. Two separate generalized linear mixed models (GLMM) of mother permissive behaviour and mother-infant contact duration as the outcome variables each showed infant age as the sole significant predictor variable indicating that as infant age increased, maternal behaviours changed as expected above, and mother-infant contact duration decreased. Mothers’ interactions with other group members appeared influenced by mothers’ associations with their offspring: adult females and juveniles were significantly more likely to be within 1-5 m proximity of mothers as infant age increased. Our data show that mother permissive behaviour, mother-infant contact duration, and proximity are crucial elements to consider when examining wild Southern Pig-tailed Macaque mother-infant relationships and infant independence, similar to what has been observed in captive settings

The prospect of rising in rank is key to long-term stability in Tibetan macaque society

One of the most fundamental questions in behavioural biology is why societies can persist for a long period of time. While researchers in animal behaviour have been hindered by a lack of an aggregate measure (such as social mobility) to quantify the dynamics of animal societies, researchers in social sciences have been challenged by the complexity and diversity of human societies. As a result, direct empirical evidence is still lacking for the hypothesized causal relationship between social mobility and social stability. Here we attempt to fill the void by examining a much simpler society in the Tibetan macaque (Macaca thibetana), which we have tracked for 30 consecutive years. By testing two group level hypotheses based on benefit-cost analysis and social stratification, we show the first quantitative evidence that an annual 2-to-1 stay/change ratio in the hierarchy with a 3-to-1 upward/downward ratio in intragenerational social mobility provides a substantive expected benefit for adult members to stay in the group and wait for their chances to advance. Furthermore, using a Markov transition matrix constructed from empirical data, we demonstrate that the 3-to-1 upward/downward ratio could lead to long-term structural stability in Tibetan macaque society

Seasonal Variation and Synchronization of Sexual Behaviors in Free-Ranging Male Tibetan Macaques (Macaca thibetana) at Huangshan, China

Although seasonal breeding has been documented in many non-human primates, it is not clear whether sexual behaviors show seasonal variation among male individuals. To test this hypothesis, the focal animal sampling method and continuous recording were used to investigate seasonal variation and synchronization of sexual behaviors in five male Tibetan macaques (Macaca thibetana) at Mt. Huangshan from Oct 2005 to Sept 2006. Both copulatory and sexually motivated behaviors (i.e., sexual chase, grimace, and sexual-inspection), which were significantly higher in the mating season than non-mating season. Furthermore, seasonal variations of sexual behaviors, including copulatory and sexually motivated behaviors, were synchronized among males. The results shed light on sexual competition and tactics for reproductive success of male M. thibetana and other non-human primates with seasonal breeding

Male Tibetan Macaques’ (Macaca Thibetana) Choice of Infant Bridging Partners

Adult male Tibetan (Macaca thibetana), Barbary (M. sylvanus), and stump-tailed macaques (M. arctoides) engage in bridging, a ritualized infant-handling behavior. Previous researchers found a bias toward the use of male infants for this behavior, but its function is debated. Explanations include three hypotheses: paternal care, mating effort, and agonistic buffering. We studied a group of habituated, provisioned Tibetan macaques to test whether adult males’ affiliative relationships with females predicted their use of an infant for bridging. We also examined biases for sex, age, and individual in males’ choice of bridging infant. We collected data via all occurrences, focal animal, and scan methods, from August to September 2011 at the Valley of the Wild Monkeys, China. We found that male infants were significantly preferred over females for bridging, but of three male infants in the group, only one was used by all males, while one male infant was used less often than expected. Adult males had females they were significantly more likely to be proximate to and/or to groom, but these corresponded to the mother of the bridging infant for only one male. Our results are most consistent with the agonistic buffering hypothesis: lower-ranked males used the alpha male’s preferred bridging infant in an attempt to regulate their interactions with the alpha

Tourist Behavior and Decibel Levels Correlate with Threat Frequency in Tibetan Macaques (Macaca thibetana) at Mt. Huangshan, China

Tourism is a common component of management practices directed toward endangered species and habitats, but few studies have explored the potential stressors that may occur to nonhumans as objects of tourism. We examined the impact that tourists have on provisioned, habituated Tibetan macaques (Macaca thibetana). Data were collected during August 2005 at the Valley of the Wild Monkeys (VWM), Mt. Huangshan, China. From a tourist viewing platform, we measured tourist densities, behaviors (for example, foot, hand, and mouth noises; mimicking monkeys; throwing objects or food), and decibel levels. Frequencies of monkey threats in the provisioning area of their range were recorded. The tourists\u27 collective behaviors correlated with monkey threats (Pearson\u27s correlations; r=0.391, p=0.014), as did decibel levels on the viewing platform (r=0.334, p=0.038). No relationship between tourist density and monkey threats, or between particular tourist behaviors and monkey threats, was significant. Based on these results, we recommend park staff be trained on how to discourage noise often associated with tourists and regulate prohibited tourist behaviors, such as feeding the monkeys. Enforcement of park rules will decrease chances that tourist-monkey interactions at VWM will escalate into situations where injuries occur, as has happened at some other macaque tourism sites. Finally, we suggest the development of tourist education materials

Sequences of Tibetan Macaque (Macaca thibetana) and Tourist Behaviors at Mt. Huangshan, China

Previous research on Tibetan macaques (Macaca thibetana) at Mt. Huangshan, China, suggested that ecotourism can have detrimental consequences. This study identified sequences of behaviors that typically occur in macaque-tourist interactions to examine whether particular tourist behaviors precipitate monkey responses. Focal sampling was used to record relevant behaviors from tourists and 10 macaques over 28 data collection sessions in August 2006. Data collectors recorded whether each behavior occurred as part of a sequence. Sequences were defined as two or more behaviors in which each behavior occurred within five seconds of the previous behavior. Of 3,129 total behaviors, 2,539 (81.1%) were from tourists and 590 (18.9%) were from monkeys. Tourists initiated significantly more sequences than did macaques (412 [84.6%] versus 75 [15.4%]). Tourist pointing, rail slapping, fleeing, and rock showing occurred significantly more than expected in tourist-macaque sequences. Points were also among the most common tourist behaviors preceding macaque threats. By discouraging tourists from engaging in these behaviors, macaque threats could be reduced, thereby improving macaque-tourist interactions. These results may aid in the management of other macaque tourist sites to minimize stress-inducing interactions

Behaviors that Predict Personality Components in Adult free-Ranging Tibetan Macaques (Macaca thibetana)

To further the potential for applied personality studies, we present a methodology for assessing personality in nonhuman animals without a priori assumptions, using behavioral measures to discriminate personality survey results. Our study group consisted of 12 free-ranging, provisioned, adult Tibetan macaques (Macaca thibetana) at the Valley of the Wild Monkeys, China. We asked familiar Chinese park guards and scientists to rate each of the 12 macaques using 27-item personality surveys. We also recorded behavioral observations (\u3e 100 hrs) from August–September, 2012. The personality surveys showed reliability in 22 of the items that were then utilized in a principal component analysis that revealed five components: Insecurity, Reactivity, Boldness, Sociability, and Leadership. Prior personality research on Macaca show comparable components. In order to determine which behaviors would best predict those five personality components, we conducted ­discriminant analyses using behavioral measures as predictors. We found that behavioral measures of avoidance, lunging, fear-grinning, self-directed behaviors, touching, proximity and chasing could significantly predict personality component scores in certain situations. Finally, we analyzed the effects of situation (provisioning and tourists) and found situation influenced proximity and rates of avoidance and self-directed behaviors. Wider implementation of this methodology may permit long-term analysis of personality using behavioral proxies for established personality traits, in particular on research investigating the effects of tourism and provisioning on personality

Sexual Interference Behaviors in Male Adult and Subadult Tibetan Macaques (\u3ci\u3eMacaca thibetana\u3c/i\u3e)

Male nonhuman primate sexual interference, which includes copulation interruption and copulation harassment, has been related to reproductive success, but its significance has been challenging to test. Copulation interruption results in the termination of a copulation before ejaculation, whereas copulation harassment does not. We conducted this study using the all-occurrence behavior sampling method on sexual interference behaviors of seven adult and four subadult male Tibetan macaques (Macaca thibetana) in mating and non-mating seasons at Mt. Huangshan, China, from August 2016 to May 2017. Our results showed that males’ individual proportion of copulation interruption and harassment was higher during the mating season than during the non-mating season. In addition, dominant males more often performed interruption, whereas subordinate males more often performed harassment. We found no difference in the individual proportion of copulation interruption or harassment between adult and subadult males. Adult and subadult males both directed copulation interruption and harassment more often toward the mating male than toward the mating female. Lastly, the post-ejaculation phase of copulation was shorter when copulation harassment occurred than when it did not. Our results suggest that sexual interference may be an important mating tactic that adult and subadult males use in male–male sexual competition

Comparative Investigations of Social Context-Dependent Dominance in Captive Chimpanzees (Pan troglodytes) and Wild Tibetan Macaques (Macaca thibetana)

Theoretical definitions of dominance, how dominance is structured and organized in nature, and how dominance is measured have varied as investigators seek to classify and organize social systems in gregarious species. Given the variability in behavioral measures and statistical methods used to derive dominance rankings, we conducted a comparative analysis of dominance using existing statistical techniques to analyze dominance ranks, social context-dependent dominance structures, the reliability of statistical analyses, and rank predictability of dominance structures on other social behaviors. We investigated these topics using behavioral data from captive chimpanzees (Pan troglodytes) and wild Tibetan macaques (Macaca thibetana). We used a combination of all-occurrence, focal-animal, and instantaneous scan sampling to collect social, agonistic, and associative data from both species. We analyzed our data to derive dominance ranks, test rank reliability, and assess cross-context predictability using various statistical analyses. Our results indicate context-dependent dominance and individual social roles in the captive chimpanzee group, one broadly defined dominance structure in the Tibetan macaque group, and high within-context analysis reliability but little cross-context predictability. Overall, we suggest this approach is preferable over investigations of dominance where only a few behavioral metrics and statistical analyses are utilized with little consideration of rank reliability or cross-context predictability

Effects of Hierarchical Steepness on Grooming Patterns in Female Tibetan Macaques (\u3ci\u3eMacaca thibetana\u3c/i\u3e)

Hierarchical steepness, defined as status asymmetries among conspecifics living in the same group, is not only used as a main characteristic of animal social relationships, but also represents the degree of discrepancy between supply and demand within the framework of biological market theory. During September and December 2011, we studied hierarchical steepness by comparing variation in grooming patterns in two groups of Tibetan macaques (Macaca thibetana), a primate species characterized by a linear dominance hierarchy. Using a focal sampling method, we collected behavioral data from two provisioned, free-ranging groups (YA1 and YA2) at Mt. Huangshan, China. We found that female dominance hierarchies were steeper in the YA1 group (0.81 based on the proportion of wins-losses and 0.66 based on dyadic dominance indices) than among members of the YA2 group (0.76 based on the proportion of wins-losses and 0.56 based on dyadic dominance indices). Females in the YA1 group groomed more frequently and for longer duration than females in YA2. Further analysis showed that grooming patterns of high- and low-ranking females did not differ between the two groups. However, middle-ranking females in YA1 groomed conspecifics more frequently and for longer duration than middle-ranking females in YA2. Our results suggest that the steepness of a dominance hierarchy plays an important role in the set of social strategies used by middle-ranking females to avoid a reduction in rank, as well as to increase their rank (the dilemma of middle class hypothesis). We suggest that future studies focus on individuals of middle-rank in order to better understand how the dynamics of rank stability and rank changes influence social relationships, and affiliative and competitive interactions in non-human primates