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One-male Units (one-male + unit)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

One-male units and clans in a colony of hamadryas baboons (Papio hamadryas hamadryas): effect of male number and clan cohesion on feeding success

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2006
Fernando Colmenares
Abstract In the multilevel societies of hamadryas baboons, adult males can be attached to single one-male units (OMUs) or to clans containing several such OMUs. This paper examines the effect of male number and rivalry between males within a clan on their ability to compete for access to a clumped food resource. The data come from a study of a multilevel colony of hamadryas baboons (Papio hamadryas hamadryas) housed at the Madrid Zoo. The colony consisted of 12 harem-holding males and 40 sexually mature females, and was organized into five single OMUs and two clans (containing three and four OMUs, respectively). The top-ranking male of one of the clans was removed and later reintroduced, so the study involved an analysis of the composition of clans and OMUs and of the males' use of the feeding area across three study periods: preseparation, separation, and reintroduction. The findings reported indicate that both males and females derived clear advantages in the context of contest competition for access to clumped food if they were members of clans, because the males and females from large clans had a feeding advantage over those from smaller clans and single OMUs. Furthermore, rivalry among males within the clan reduced their ability to compete for food against males outside their clan. This paper provides empirical evidence for one of the potential advantages that hamadryas males may enjoy if they are attached to clans, and also provides empirical support for the general hypothesis that a large number of males in a group may provide fitness-related benefits to the group members, provided they are able to cooperate with each other. Am. J. Primatol. 68:21,37, 2006. © 2006 Wiley-Liss, Inc. [source]

Eurasian blackbird predated by wild Rhinopithecus roxellana in the Qinling Mountains, China

INTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 3 2008
Dapeng ZHAO
Abstract Although there are some reports that have described primates eating animals, it is unknown whether predation on vertebrates exists in herbivorous leaf-eating primates. We have witnessed firsthand wild Sichuan snub-nosed monkeys (Rhinopithecus roxellana) preying on and consuming Eurasian blackbirds (Turdus meruld) in the Qinling Mountains of China. This event suggests that R. roxellana, which has previously been described as a herbivorous leaf-eating primate, may be partially carnivorous and the correct classification of this species would be omnivorous. Furthermore, food-share behavior among higher-ranked members occurs in a one-male unit when vertebrate prey is hunted by this species. [source]

A Bayesian analysis of the temporal change of local density of proboscis monkeys: Implications for environmental effects on a multilevel society

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010
Ikki Matsuda
Abstract To understand the effects of environmental factors on a social system with multilevel society in proboscis monkey units, the temporal change of the local density of sleeping sites of monkeys was investigated along the Menanggul river from May 2005 to 2006 in Malaysia. Proboscis monkeys typically return to riverside trees for night sleeping. The sleeping site locations of a one-male unit (BE-unit) were recorded and the locations of other one-male and all-male units within 500 m of the BE-unit were verified. In addition, environmental factors (food availability, the water level of the river, and the river width) and copulation frequency of BE-unit were recorded. From the analyses of the distance from the BE-unit to the nearest neighbor unit, no spatial clumping of the sleeping sites of monkey units on a smaller scale was detected. The results of a Bayesian analysis suggest that the conditional local density around the BE-unit can be predicted by the spatial heterogeneity along the river and by the temporal change of food availability, that is, the local density of monkey units might increase due to better sleeping sites with regard to predator attacks and clumped food sources; proboscis monkeys might not exhibit high-level social organization previously reported. In addition, this study shows the importance of data analysis that considers the effects of temporal autocorrelation, because the daily measurements of longitudinal data on monkeys are not independent of each other. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source]

The fourth level of social structure in a multi-level society: ecological and social functions of clans in hamadryas baboons

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2009
Amy L. Schreier
Abstract Hamadryas baboons are known for their complex, multi-level social structure consisting of troops, bands, and one-male units (OMUs) [Kummer, 1968. Social organization of hamadryas baboons. Chicago: The University of Chicago Press. 189p]. Abegglen [1984. On socialization in hamadryas baboons: a field study. Lewisburg, PA: Bucknell University Press. 207p.] observed a fourth level of social structure comprising several OMUs that rested near one another on sleeping cliffs, traveled most closely together during daily foraging, and sometimes traveled as subgroups independently from the rest of the band. Abegglen called these associations "clans" and suggested that they consisted of related males. Here we confirm the existence of clans in a second wild hamadryas population, a band of about 200 baboons at the Filoha site in lowland Ethiopia. During all-day follows from December 1997 through September 1998 and March 2005 through February 2006, data were collected on activity patterns, social interactions, nearest neighbors, band fissions, and takeovers. Association indices were computed for each dyad of leader males, and results of cluster analyses indicated that in each of the two observation periods this band comprised two large clans ranging in size from 7 to 13 OMUs. All band fissions occurred along clan lines, and most takeovers involved the transfer of females within the same clan. Our results support the notion that clans provide an additional level of flexibility to deal with the sparse distribution of resources in hamadryas habitats. The large clan sizes at Filoha may simply be the largest size that the band can split into and still obtain enough food during periods of food scarcity. Our results also suggest that both male and female relationships play a role in the social cohesion of clans and that males exchange females within clans but not between them. Am. J. Primatol. 71:948,955, 2009. © 2009 Wiley-Liss, Inc. [source]

Social dynamics of the golden snub-nosed monkey (Rhinopithecus roxellana): female transfer and one-male unit succession

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 8 2009
Xiao-Guang Qi
Abstract Among primates that form multilevel societies, understanding factors and mechanisms associated with the movement of individuals between groups, clans, and one-male social units offers important insight into primate reproductive and social strategies. In this research we present data based on an 8-year field study of a multilevel troop of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains of China. Our study troop contained 78,126 individuals, and was usually organized into 6,8 one-male units (OMU). The majority of OMUs were composed of networks of unrelated females and their offspring. We found that 59.7% (43/72) of subadult and adult females in our study troop transferred between OMUs (n=66) or disappeared (n=7) from the troop. In the majority of cases, two or more females transferred together into new OMUs or troops. In R. roxellana, new OMUs formed in several ways. During 2001,2008, 16 adult males appeared in the study troop. Over this period, we observed 13 different males who became harem leaders either by taking over an existing harem or by attracting females from other OMUs into their harem. We also observed four OMUs from a neighboring troop to successfully immigrate into the study troop. The number of individuals in these newly immigrated OMUs was significantly smaller than that number of individuals in resident OMUs. During harem formation, fighting between adult males was rarely observed, and female mate choice appeared to play a crucial role in harem male recruitment and replacement. These results suggest that golden snub-nosed monkeys are organized in a nonmatrilineal social system. Female mate choice and possibly incest avoidance appear to play important roles in female transfer, male tenure, and OMU stability. Am. J. Primatol. 71:670,679, 2009. © 2009 Wiley-Liss, Inc. [source]

Female social dynamics in a provisioned free-ranging band of the Sichuan snub-nosed monkey (Rhinopithecus roxellana) in the Qinling mountains, China

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2008
Peng Zhang
Abstract Little information is available on the social dynamics of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana). Here, we provide 5-year observational data on a provisioned free-ranging band in the Qinling Mountains, central China, from October 2001 to December 2005. The results of this study suggested that females place a high priority on maintaining long-term relationships with other female in their one-male units (OMUs). Females had more social interactions with unit members than with nonunit individuals. They showed relatively high rates of affiliation with their unit females, intermediate levels with the resident males, and low levels with individuals outside the unit. Females had few interactions with other resident males. Social interactions, especially affiliative interactions, were more symmetrical between focal females and their unit females than between focal females and the resident males. Thus female social interactions appeared to resemble those of other female-bonded primate societies. On the other hand, female transfers occurred sometimes. We recorded 11 cases of female immigration and 5 cases of female disappearance, 1 case of female intraband shift, and 2 cases of "merging of OMUs," which suggested that unit females might be loose-knit in this species. We discussed influencing factors on female Sichuan snub-nosed monkey social dynamics, by comparing them with those of Hamadryas and gelada baboons that also have multilevel societies. Am. J. Primatol. 70:1013,1022, 2008. © 2008 Wiley-Liss, Inc. [source]

Dominance relationships among one-male units in a provisioned free-ranging band of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains, China

AMERICAN JOURNAL OF PRIMATOLOGY, Issue 7 2008
Peng Zhang
Abstract We studied the dominance relationships among one-male units (OMUs) in a provisioned free-ranging band of the Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in the Qinling Mountains of central China from 2001 to 2005. The band was composed of 6,8 OMUs that stayed in the band for several years. Linear dominance orders could be detected using displacement interactions with directional asymmetry among OMUs in 82.3±5% of interactions, and ambiguous and reversed interactions in 17.7±5%. The dominance rank of OMUs was positively related with the duration of their stay in the band, and this may be attributed to the association of the resident male with adult females, rather than the fighting ability of resident males, as males do not fight seriously with each other. Subordinate units were observed to merge with dominant units resulting in an elevation of their rank order. The linear dominance relationship among OMUs in the Sichuan snub-nosed monkeys may have evolved as a result of competition for preferred food trees. Am. J. Primatol. 70:634,641, 2008. © 2008 Wiley-Liss, Inc. [source]