Primate Research Supplement

One-male unit (OMU) is the basic social unit in multi-level societies of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana). From October, 2001 to December, 2005, we studied dominance relationships between OMUs in a free ranging group in the Qinling Mountains, central China. The group was comprised of 6 to 8 OMUs that were cohesively associated. We analyzed a total of 2366 replacement interactions among these OMUs during eight different study periods. The results suggested a linear dominance relationship among the units in each study period. We suggest three factors that may influence dominance relationships among units: long-term association, competition for food trees and influence of provisioning. The results showed time positive ranks in the group, which is units associating for longer time in the group tend to have higher dominance rank. In addition, we reported for the first time that two cases of 'merger of OMUs', in which one resident male replaced the other, and merged two units into one. We discussed the dynamics of merger of OMUs.

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Inter-group encounters provide a medium whereby inferences regarding the nature of resource competition between conspecific primate groups can be made. Where encounters are aggressive, they may reflect: 1) female competition for access to food; 2) male competition for mating access; 3) indirect male mating competition through defence of food; and 4) male threat of infanticide as a coercive means. These are not mutually exclusive. This study tested whether social vigilance may indicate competitive regime. Individual variations may contextually reflect gender-based competitive strategies. Vigilance was analyzed in relation to the above hypotheses. Encounters did have an impact on vigilance as expected. I argue that vigilance in C. vellerosus is more a function of male behaviour and less related to female feeding competition.

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Introduction: Assessments of chimpanzees with the Hominoid Personality Questionnaire (HPQ) has revealed the presence of a broad chimpanzee-specific Dominance factor and five factors analogous to those in humans --- Extraversion, Conscientiousness, Agreeableness, Neuroticism, and Openness. These factors were reliable, generalized to naturalistic and laboratory settings, and related to behavior and subjective well-being. In Japan, 80 chimpanzees at Sanwa were assessed using the Yatabe-Guilford Personality Inventory (YG). We wanted to determine whether the HPQ yields similar personality domains in Japanese chimpanzees and whether they were related to the YG domains and subjective well-being.
Methods: Three raters assessed each of the 80 chimpanzees on the Y-G and HPQ and at least 2 raters assessed 30 additional chimpanzees on the HPQ and a subjective well-being questionnaire.
Results: Principal components analyses (PCA) revealed 4 YG domains and 6 HPQ domains. YG Extraversion was correlated to HPQ Extraversion, Dominance, Openness, and Agreeableness; YG Neuroticism was negatively correlated to all HPQ domains except Openness; YG Depression was negatively correlated to HPQ Dominance and Extraversion; and YG Dominance was correlated to HPQ Dominance, Extraversion, Conscientiousness, and Agreeableness. As expected, HPQ Dominance, Extraversion, and Neuroticism were correlated to subjective well-being.
Discussion: The HPQ can be used to compare the personality of Japanese chimpanzees to that of chimpanzees in other countries or related species, including humans.

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Eight mother-young pairs of free ranging Japanese macaques, sampled equally from two groups and divided in two set of young (weaned infant less than one year old and juveniles aged between 1.5 and 2 years old), were followed during three months in winter 2005-2006. I systematically recorded the intense behavioural observation directed toward elder by young of the two age-classes, the items manipulated by the elder and closely observed and the immediate post-behaviour displayed by young as well as the items or the location explored. Moreover, I estimated the mothers and juveniles diet from the proportion of occurrences for each food items ingested and from the quantity of fresh matter ingested. It appeared that the intense behavioural observation of both infants and juveniles were directed toward elders engaged in a feeding behaviour on the main food items (mainly fruit, seed) or in an insect foraging behaviour. Infants exhibited the intense behavioural observation more frequently than juveniles. They also showed the intense observational behaviour toward elder other than their mothers, while juveniles did not. Moreover, after having paid an attentive attention the elder's foraging behaviour, infants displayed the same behaviour as the elders and that more frequently than juveniles. These results match the juveniles-adult dependent model of social transmission of information described by King (2005). Furthermore, the intense behavioural observations relevant of late infant stage corresponded to the phase of transition between a milk diet and a solid diet and might be certainly considered as a behavioural process to obtain information about critical survival skills as edible and rich-food in sugar, lipid and protein selection and location.

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