Search

Social organisms make collective decisions during group movement, thereby remaining cohesive and providing the ecological and evolutionary benefits of sociality. The ability for groups to make successful collective decisions is dependent on relationships between leaders and followers. We investigated how consistent followers (a fan structure) facilitated successful group movement in a group of Tibetan macaques, Macaca thibetana , at Mt. Huangshan in Anhui, China. We used structural equation modelling to determine the relative influences of sex, age, number of maternal familial connections within the group, dominance and social network centrality on the number of fans that an individual had and the number of other group members that an individual was a fan of (fandom). Our structural equation modelling revealed that dominant females had more fans, while younger, dominant individuals with more familial connections were fans of more individuals. Fans and fandom were most strongly influenced by dominance, displaying a strong network of females occupying top positions in the dominance hierarchy who consistently followed each other. In addition, we examined the relationship between fan structure and movement speed and success. Using regression, we found a positive relationship between fans and speed and a negative correlation between fans and number of unsuccessful movements, suggesting a link between the social connections maintained in a movement and the speed of the movement. Dominant females with more fans initiated slower movements, perhaps because the complex fan structure slowed the joining process. However, individuals with more fans led fewer unsuccessful movements, suggesting a relationship between fans and initiation success. Our findings show a network of social relationships within Tibetan macaque groups that are used during movement organization to maintain cohesion and mediate the benefits of sociality. Highlights • We studied Tibetan macaque decision making during collective movement. • Dominant females had the most consistent followers during movement. • Dominant, younger individuals with more kin consistently followed more individuals. • Individuals with more consistent followers led slower movements. • Individuals with more consistent followers had fewer unsuccessful movement initiations. [ABSTRACT FROM AUTHOR]

In several primate species, adult males are reported to compete for access to reproductive partners as well as forming affiliative and cohesive social bonds based on the exchange of goods or services. We hypothesized that among a broad set of fitness-maximizing strategies, grooming can be used by individual adult males to enhance social relationships through reciprocity and/or through the interchange of grooming for a different but equivalent good or service. We used focal animal sampling and continuously recorded dyadic grooming and agonistic interactions to test a series of predictions regarding male social interactions in a free-ranging group of Tibetan macaques ( Macaca thibetana) at Huangshan, China. During the non-mating season or between males of similar rank throughout the year, grooming effort given was matched by grooming effort received. However, lower ranking males groomed higher ranking males at a greater rate and/or for a longer duration during both the mating and non-mating periods. We found that higher ranking males directed less aggression towards males with whom they formed a frequent grooming partnership, indicating that grooming received was interchanged for increased social tolerance. These data suggest that individual male Tibetan macaques employ alternative social strategies associated with grooming reciprocity or interchange depending on dominance rank and rates of aggression, and highlight the importance of both biological markets and grooming reciprocity as behavioral mechanisms used by resident adult males to form and maintain affiliative social bonds. Am. J. Primatol. 75:1009-1020, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Predicting the spatial distribution of species and suitable areas under global climate change could provide a reference for species conservation and long‐term management strategies. Macaca thibetana and Macaca arctoides are two endangered species of Chinese macaques. However, limited information is available on their distribution, and their habitat needs lack proper assessment due to complicated taxonomy and less research attention. In recent years, scholars widely used the maximum entropy (MaxEnt) model to predict the impact of global climate and certain environmental factors on species distribution. Therefore, we used the MaxEnt model to predict the spatiotemporal distribution of both macaque species under six climate change scenarios using occurrence and high‐resolution ecological data. We identified climatic factors, elevation, and land cover that shape their distribution range and determined shifts in their habitat range. The results demonstrated that temperature range, annual precipitation, forest land cover, and temperature seasonality, including the precipitation of the driest month are the main factors affecting their distribution. Currently, M. thibetana is mainly concentrated in central, eastern, southern, and southwestern China, and M. arctoides is mainly concentrated in three provinces (Yunnan, Guangxi, and Guangdong) in southern China. The MaxEnt model predicted that the suitable habitat for both species will increase with increased greenhouse emission scenarios. We also found that with the further increase in greenhouse emissions M. thibetana is expected to migrate to western China, and M. arctoides is expected to migrate to western or eastern China. This reinterpretation of the distribution of M. thibetana and M. arctoides in China, and predicted potential suitable habitat and possible migration direction, may provide new insights into the future conservation and management of these two species. Highlights: Potential macaque distributions were predicted using different climate change scenarios.Macaque distributions were compared under present and future climate conditions.Suitable habitat areas for Macaca thibetana and Macaca arctoides are expected to increasing.Annual precipitation and annual temperature affected distribution.We believe the two species are migrating to the west of China to adapt to climate change. [ABSTRACT FROM AUTHOR]

In group‐living mammals, an individual's fitness depends, in part, on the quality of social relationships it has with others. Among species of nonhuman primates in which one sex is philopatric, individuals of that sex often develop strong social bonds and alliances with closely related kin. Less is known regarding the social processes used by dispersing adults to form stable bonds with nonkin in their new group. From May to December 2009, April to August 2010, September to December 2011, and February to May 2012, we collected data on grooming interactions in wild Tibetan macaques (Macaca thibetana), a female philopatric species, at Mt. Huangshan, China. Our goal was to compare social interactions and bond formation between resident males, recent immigrant males, and resident females. Our results indicate that recent immigrant males formed stable partner relationships with a small number of resident females and groomed these females more frequently or for longer than they received grooming. In contrast, resident males switched female grooming partners more frequently, received more grooming than they gave, and formed relationships with a greater number of female partners. We argue that the ability of recent immigrant male Tibetan macaques to maintain strong and persistent social bonds with a small set of resident adult females is a primary factor that enables them to establish residence in a new multimale–multifemale group. The present study provides new and important insights into the integrated social strategies used by dispersing males and resident females to maintain group stability. Highlights: Recent immigrant male Tibetan macaques establish strong social bonds and persistent partnerships with a small number of resident females as a social tool to integrate into their new group.In contrast, males who are long‐term residents of the group, frequently change female partners and exhibit less stable partner relationships.The study provides new and important insights into the integrated social strategies used by recent immigrant males, long‐term resident males, and resident females in maintaining group cohesion in a multimale–multifemale primate society. [ABSTRACT FROM AUTHOR]

Coordination and consensus in collective behavior have attracted a lot of research interest. Although previous studies have investigated the role of compromisers in group consensus, they provide little insight into why compromisers would allow such social arrangements to persist. In this study, the potential relationship between group movements and conflict management in Tibetan macaques in Anhui province, China, was investigated using hierarchical cluster analyses. Some members with higher social centrality or social rank often formed a front-runner cluster during group movements. They had higher leadership success than individuals outside the front-runner cluster. Other members with lower social centrality or social rank often followed the group movements initiated by the front-runner cluster, and thus formed the compromiser cluster. Compromisers' proximity relations with front-runners increased with their following scores to front-runners. Compromisers had fewer events of being attacked when they followed group movements initiated by the front-runners. The compromising process made compromisers lose the choice of direction preference, but it could increase their individual safeties. This trade-off suggests that compromisers play a role of decision-maker in coordination and consensus scenarios among social animals. [ABSTRACT FROM AUTHOR]

Leadership is a key issue in the study of collective behavior in social animals. Affiliation–leadership models predict that dyadic partner preferences based on grooming relationships or alliance formation positively affect an individual's decision to follow or support a conspecific. In the case of many primate species, females without young infants are attracted to mother–infant dyads. However, the effects of mother–infant–female associations on affiliation–leadership models remain less clear. In free-ranging Tibetan macaques Macaca thibetana , we used social network analysis to examine the importance of "mother-infant-adult female" social bridging events as a predictor of who leads and who follows during group movement. Social bridging is a common behavior in Tibetan macaques and occurs when 2 adults, generally females, engage in coordinated infant handling. Using eigenvector centrality coefficients of social bridging as a measure of social affiliation, we found that among lactating females, initiating bridging behavior with another female played a significant role in leadership success, with the assisting female following the mother during group movement. Among nonlactating females, this was not the case. Our results indicate that infant attraction can be a strong trigger in collective action and directing group movement in Tibetan macaques and provides benefits to mothers who require helpers and social support in order to ensure the safety of their infants. Our study provides new insights into the importance of the third-party effect in rethinking affiliation–leadership models in group-living animals. [ABSTRACT FROM AUTHOR]

Recent studies highlight that the gut mycobiota play essential roles in mammalian metabolic and immune systems, but to date we lack information on the forces that naturally shape the gut mycobiota of wild primates. To investigate the contributions of host and environmental factors in the taxonomic variation of the gut mycobiota, we examined the effects of age, sex, and season on the fecal mycobiota in wild‐living Tibetan macaques (Macaca thibetana). Using next generation sequencing and a longitudinal set of fecal samples collected over 1 year, we identified a set of core fungal taxa present in the Tibetan macaque's fecal samples. The predominant genera Aspergillus and Penicillium, which promote the digestion of cellulose and hemicellulose in herbivorous mammals, were detected in this study. Similar to humans, we found age and sex effects on the macaques’ fecal mycobiota. We also found that both fecal fungal composition and diversity (alpha and beta diversity) varied significantly by season. In particular, the Penicillium enriched mycobiota in summer samples may aid in the digestion of cellulose and hemicellulose present in mature leaves. The high alpha diversity detected in Tibetan macaques’ winter fecal samples may facilitate a diet rich in fiber ingested during this season. We propose that the gut mycobiota play an important role in the macaques’ ability to adapt to seasonal fluctuations in food availability and nutrient content. [ABSTRACT FROM AUTHOR]

Vocal repertoires are basic and essential components for describing vocal communication in animals. Studying the entire suite of vocal signals aids investigations on the variation of acoustic structure across social contexts, comparisons on the complexity of communication systems across taxa, and in exploration of the evolutionary origins of species-specific vocalizations. Here, we describe the vocal repertoire of the largest species in the macaque genus, Macaca thibetana. We extracted thirty acoustic parameters from call recordings. Post hoc validation through quantitative analyses of the a priori repertoire classified eleven call types: coo, squawk, squeal, noisy scream, growl, bark, compound squeak, leap coo, weeping, modulated tonal scream, and pant. In comparison to the rest of the genus, Tibetan macaques uttered a wider array of vocalizations in the context of copulations. Previous reports did not include modulated tonal screams and pants during harassment of copulatory dyads. Furthermore, in comparison to the rest of the genus, Tibetan macaque females emit acoustically distinct copulation calls. The vocal repertoire of Tibetan macaques contributes to the literature on the emergence of species-specific calls in the genus Macaca with potential insights from social, reproductive, and ecological comparisons across species. Am. J. Primatol. 78:937-949, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Research on leadership is a critical step for understanding collective decision making. However, only 4 of the 22 extant macaque species have been examined for the impact of social rank and affiliation on the initiation of collective movement. It is far from clear whether such impact exists and, if so, how it works among other macaques. To answer these questions, we investigated free-ranging, Tibetan macaques' ( Macaca thibetana) group departures from a provisioning area and tested two alternative hypotheses: personal versus distributed leadership. Personal leadership predicts that a single, highest ranking individual initiates the most group movements, whereas distributed leadership predicts that different members lead the group on different occasions and affiliative individuals have more initiations. We recorded how often and how successfully adults initiated group movements from a provisioning area into the forest, and related these variables to the duration of interindividual proximity and grooming time in the forest. All adults initiated group movements, but did so variably. Social rank was related neither to the number of successful initiations nor to the success ratio of initiations. By contrast, eigenvector centrality based on proximity relations was positively correlated with the number and ratio of successful initiations. Moreover, successful initiations were positively correlated with social grooming. Overall, Tibetan macaques showed a pattern of distributed leadership. Our study demonstrated the relationship between social affiliation and individual leadership in a macaque society. Am. J. Primatol. 78:816-824, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Simple Summary: Social play among immature individuals has been well-documented across a wide range of mammalian species. It represents a substantial part of the daily behavioral repertoire during immature periods, and it is essential for acquiring an appropriate set of motor, cognitive, and social skills. In this study, we found that infant Tibetan macaques (Macaca thibetana) exhibited similar patterns of social play between males and females, juvenile males engaged more aggressive play than juvenile females, and juvenile females engaged more affiliative play than juvenile males. Our results provided more evidence to understand the functional differences of social play in immature nonhuman primates. Theories proposed to explain social play have centered on its function in establishing social relationships critical for adulthood, its function in developing motor skills needed to survive, and promoting cognitive development and social learning. In this study, we compared variations in social play among infant and juvenile male and female Macaca thibetana. Given that this species is characterized by female philopatry and male dispersal, we hypothesized that immature females use social play as a mechanism to develop bonds that persist through adulthood whereas immature males use play to develop social skills needed to successfully enter new groups. The results indicated that social play steadily increased during the infant period and peaked at approximately 12 months of age. There were no significant differences in the frequency or types of social play exhibited between infant males and infant females. During the juvenile period, however, social play was found to decrease with age, with males engaging in social play more frequently than juvenile females. Moreover, whereas juvenile males engaged in more aggressive forms of play, juvenile females engaged in more affiliative forms of play. In addition, juvenile females engaged in higher rates of grooming than juvenile males. These results provide evidence of sex-specific differences and imply the functional variation of social play in Tibetan macaques, with immature males using social play to develop skills needed to enter and enhanced their dominance rank in a new social group and immature females using social play to develop long-term same-sex social bonds in their natal group. [ABSTRACT FROM AUTHOR]

Simple Summary: Sexual interference behaviors (interruption/harassment) by male nonhuman primates can lead copulating individuals to separate and is hypothetically a form of male–male competition for access to sexually receptive females. Tibetan macaques (Macaca thibetana) provide an example of male sexual interference that can be used to discuss the sexual competition hypothesis. We found male sexual interference in this species showed significant seasonal variation. Age did not affect the proportion or type of interference behaviors that a male performed, but his social status did. Dominant males more often interrupted copulations. Subordinate males more often directed harassment behaviors toward dominant males, which reduced copulation duration, especially the post-ejaculatory phase of copulation. Our results suggest that sexual interference (interruption or harassment) may be a tactic to reduce the mating success of other males by either preventing ejaculation or reducing the duration of the post-ejaculatory phase, which is critical for sperm transport and, thus, reproductive success. 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. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]