Social organization of captive monandrous squirrel monkey groups (Saimiri sciureus).

1 adult male and 4 adult female squirrel monkeys were observed together as a group, isolated from all other monkeys. 3 of the 4 females were deafened for a previous experiment. Deafening, however, had no apparent, permanent effect on social behavior. Social dominance hierarchy was evaluated in a variety of situations. The results were compared with those of a similar set of observations on the females prior to the introduction of the male. Before the male was introduced, the dyadic interactions involving food stealing, body grasping, and sexual behaviors were indicative of a female linear rank order. After the male was introduced, the rank order among the females generally remained intact, with the male becoming the highest ranking member in the group. The noteworthy exception to the stability involved the highest ranking female, whose position in the hierarchy was threatened. Heterosexual interactions predominated. Homosexual behavior was also observed, although appreciably reduced in frequency as compared to the all-female group situation. A similar rank order hierarchy was observed in a second group of squirrel monkeys comprised of 1 adult male and 4 adult females. None of these monkeys was deaf.     

Dominance and its Behavioral Measures in a Captive Group of Bonobos (Pan paniscus)

We investigated the existence of a social dominance hierarchy in the captive group of six adult bonobos at the Planckendael Zoo. We quantified the pattern of dyadic exchange of a number of behaviors to examine to what extent each behavior fits a linear rank order model. Following de Waal (1989), we distinguish three types of dominance: agonistic dominance, competitive ability and formal dominance. Fleeing upon aggression is a good measure of agonistic dominance. The agonistic dominance hierarchy in the study group shows significant and strong linearity. The rank order was: 1. female (22 yr), 2. female (15 yr)., 3. male (23 yr.), 4. female (15 yr.), 5. male (9 yr.), 6. male (10 yr.). As in the wild, the females occupy high ranks. There is prominent but nonexclusive female agonistic dominance. Teeth-baring does not fulfil the criteria of a formal submission signal. Peering is a request for tolerance of proximity. Since its direction within dyads is consistent with that of fleeing interactions, it is a useful additional measure to determine agonistic ranks in bonobos. In competitive situations, the females acquire more food than other group members do. The rank obtained from access to food resources differs from the agonistic rank due to female intrasexual social tolerance, expressed in food sharing. We typify the dominance styles in the group as female intrasexual tolerance and male challenging of rank differences. The agonistic rank order correlates significantly with age and has a strong predictive value for other social behaviors.     

Female-female social relationships in wild white-faced capuchin monkeys,Cebus capucinus

A single social group of wild white-faced capuchin monkeys was studied for a period of 26 months at Lomas Barbudal Biological Reserve, Costa Rica. A total of 604 hr of focal animal data was collected on six adult females in a group of 21 monkeys. Females could be ranked in a stable, linear dominance hierarchy. Adult females spent much more time in proximity to other adult females than to adult males. Females groomed other females twice as often as they groomed males, and about 55 times more often than males groomed males. Females tended to groom up the dominance hierarchy, and dyads with smaller rank distances groomed more often. Higher-ranking females nursed infants other than their own at lower rates than did lower-ranking females; however, females nursed infants of females ranked both above and below them. Although lower-ranking females were more likely than higher-ranking females to be the victims of aggression, higher-ranking females were not necessarily more aggressive than lower-ranking females. In 96% of female-female coalitions vs. a female, the victim was lower-ranking than both coalition partners; in the remaining 4%, the victim was intermediate in rank between the two coalition partners. Higher-ranking female-female dyads formed coalitions more often than did lower-ranking dyads. Those female-female dyads that groomed more frequently also formed coalitions more frequently. The patterning of social interactions indicates that Cebus capucinus at Lomas Barbudal are female bonded. © 1996 Wiley-Liss, Inc.     

The formal hierarchy of rhesus macaques: An investigation of the bared-teeth display

Teeth-baring in a large captive rhesus monkey group (Macaca mulatta) was observed over a 30-month period. Its directional consistency among adults was significantly higher than that of aggression. The unidirectionality was so extreme that the facial display must be seen as a formal status indicator; ie, a signal of which the direction is independent of short-term contextual variation. As such, it seems adapted for communication about the state of the relationship. Formal dominance relationships among adults could be arranged in a hierarchy which approached perfect linearity. Focal observations demonstrated that teeth-baring was associated with withdrawal. It was uncommon among foraging monkeys, perhaps because dominant animals paid less attention to their subordinates in this context. The speed of rank acquisition by young females, in terms of received teeth-baring, was highest among peers and lowest against the group's old matriarchs. The age at which dominance over unrelated adult females was achieved correlated negatively with the amount of affiliative contact with these females. This translates into a positive correlation between bonding and rank establishment, indicating that dominance processes may be indistinguishable from social integration.     

Dominance,grooming, and clasped-sleeping relationships among bonnet monkeys in India

Social relationships, including dominance, grooming, and clasped-sleeping, were studied in a troop of bonnet monkeys (Macaca radiata) at Dharwar, India, the study period lasting two months and a half. Three measurements, the peanut test, the drinking test, and the spatial distribution test, were used to analyze dominance relationships. The peanut test showed a straight linear ranking order among adult males and females; however, among females drinking and spatial distribution orders are slightly different from that of feeding (peanut test). Grooming was observed more frequently between adult female and adult female and was seldom observed between adult male and juvenile female or between juvenile male and juvenile female. Apparently all monkeys tend to groom with females. On the other hand, monkeys of the same sex tend to sleep with each other. It is clear that monkeys select their partners when they groom and sleep.     

Toward a comparative socioecology of the genus Macaca: Different dominance styles in rhesus and stumptail monkeys

Captive studies can make a unique contribution to primate socioecology by documenting species-typical social dispositions under controlled conditions. Recent theories seek to connect the dominance relationships, group cohesiveness, and feeding ecology of primates. The present study explores the first two aspects by comparing the social organization of rhesus (Macaca mulatta) and stumptail monkeys (M. arctoides). Data were collected over a period of eight years, with five different methods, on three well-established captive groups in identical environments. The groups were found to share one characteristic: a clear-cut, linear formal dominance hierarchy as expressed in teeth-baring displays. The two main study groups (one of each species) differed significantly, however, with respect to nine of eleven behavioral measures. In addition to a previously reported higher frequency of reconciliation in the stumptail group, this group showed (1) more frequent but less severe aggressive behavior, (2) greater symmetry of contests, (3) greater social tolerance, (4) more nonagonistic approaches, and (5) more allogrooming. The differences can be summarized as a contrast in dominance “style,” with the stumptails having a more relaxed style and placing greater emphasis on social cohesion than the rhesus monkeys. An egalitarian attitude was also reflected in approach behavior: contacts in the rhesus group were mostly initiated by dominants, whereas contacts in the stumptail group were initiated independent of rank. Comparisons with a second rhesus group, and with published reports, suggest that while some of the observed differences are probably representative of the two species, considerable intraspecific variation does exist, and a more comprehensive program of comparative studies is needed.     

Agonistic behavior and dominance relationships in female Phayre's leaf monkeys -- preliminary results

Socioecological theory suggests a link between the strength of competition for food/safety, rates of agonism, structure of dominance hierarchies, and dispersal among group-living females. This study presents preliminary data on agonistic behavior and dominance relationships for female Phayre's leaf monkeys (Trachypithecus phayrei), a species in which females routinely disperse. Behavioral observations were conducted on two groups (four adult females, and five adult females plus two juvenile females, respectively) at Phu Khieo Wildlife Sanctuary, northeast Thailand. Rates of agonistic behavior were analyzed from focal continuous recordings, while dominance hierarchies were constructed from all agonistic behaviors (focal and ad libitum sampling). Overall, female-female agonistic behaviors (aggression, submission, and displacements) occurred at a rate of < 0.25 interactions per hour. Agonistic interactions involving food occurred more frequently than expected based on feeding time. Females in both groups exhibited linear dominance hierarchies with some reversals, and possibly an age-inversed hierarchical structure in the larger group. The results fit well with previous results for colobine monkeys regarding frequency of interactions, displacements predominating agonistic behavior, and the possibility of an age-inversed hierarchy. The results contradict the suggested link between linearity of hierarchies and female philopatry. Future studies should consider the notion that female dispersal may coexist with linear dominance hierarchies.     

A Young Manakin Knows His Place: Evidence for an Age‐Graded Dominance Hierarchy Among Long‐Tailed Manakins

In lek‐breeding systems where many males gather at display sites, males benefit from the establishment of dominance hierarchies to reduce intrasexual aggression and the associated risk of injuries. Long‐tailed manakins (Chiroxiphia linearis) exhibit an exploded lek‐breeding system wherein the two top‐ranking males at each display site team up to perform elaborate coordinated courtship displays for females. Young males undergo delayed plumage maturation whereby they acquire distinct pre‐definitive plumage patterns each year until they attain definitive plumage in their fifth year. This unique characteristic is thought to have evolved as a status‐signalling mechanism to aid in the establishment of an age‐graded dominance hierarchy in which older males are dominant to younger males. Previous research has shown evidence for such a dominance hierarchy among alpha and beta males; however, the presence of this hierarchy among males of other age classes has never been quantified. In this study, we investigated the presence of an age‐graded dominance hierarchy by determining whether older males direct more aggressive behaviours towards younger males. We also investigated whether status signalling is less clear within age classes than between age classes, by determining whether males within the same age class exhibit more aggression towards each other. We found that older males performed aggressive behaviours towards younger males much more frequently than younger males performed aggressive behaviours towards older males. We also found that some aggressive interactions occurred between males within the same age class more frequently than between males from different age classes. Our study provides some evidence for an age‐graded dominance hierarchy among male long‐tailed manakins of all age classes and also provides some support for the status‐signalling hypothesis. However, further research is needed to conclusively establish the presence of a linear dominance hierarchy among younger male manakins. This research may help us better understand the evolution of complex hierarchical systems in animals.     

Social organization and social behavior in two subspecies of squirrel monkeys (Saimiri sciureus).

Social organization and social behavior were examined in two subspecies of squirrel monkeys which differ markedly in the degree of sexual dimorphism. The Bolivian squirrel monkeys, the subspecies with greater sexual dimorphism, manifested a sexually segregated form of social organization, while the social organization of the Guyanese monkeys was sexually integrated. Dominance relationships were found to reflect these patterns of sexual segregation or integration; in the Bolivian social groups separate linear dominance hierarchies were established within each sex while the Guyanese monkeys established a single linear hierarchy which included both males and females. Relationships between males and females in the two subspecies appear to be regulated by two distinct mechanisms, dominance in the Guyanese monkeys and sexual segregation in the Bolivians.     

Rank and age related feeding strategy observed through field experiments in the Koshima group of Japanese macaques

The feeding process of Japanese monkeys on soy beans which were scattered over a sandy beach on Koshima islet was studied. Younger monkeys were able to pick up more beans when 8 kg of beans were divided and given two times (“two times feeding”) than when the whole amount (8 kg) of beans was given at one time (“one time feeding”). The effect of saturation of the food intake capacity in younger monkeys at the first feeding in “two times feeding” did not appear at the second feeding one hour later. The minutely intake of soy beans (feeding speed) for each age class was analyzed. The decline of feeding speed in adult females after the peak in “one time feeding” was not related to the decline in density of beans on the ground, and this decline was caused by saturation of their food intake capacity. Adult females were divided into four classes according to their dominance rank order: high, lower-high, higher-low, and low classes. The total amount of intake in “one time feeding” was far larger in the high class than in any of the other classes. The total amount of feeding in the first feeding of “two times feeding” increased in accordance with rise in the dominance rank class, and there was no relation to rank and total feeding amount in the second feeding of “two times feeding.” Differences existed in the process of feeding between the rank classes. The feeding speed of the low class was as high as that of the high class on the curve of minutely intake, while the low class stopped feeding much earlier than the high class. The lower-high class displayed a low feeding speed, and stopped feeding the latest. The order of the duration to stay and to feed in the feeding area was lower-high > high > higher-low > low, and this order did not change under the three different feeding conditions, “one time feeding,” and the first and second feedings of “two times feeding.” Adolescent females tended to stay the longest duration in the feeding area among all age classes. Both the lower-high class females and adolescent females had an unstable social status in the Koshima group, and their social status affected their feeding behaviors. The feeding behaviors were similar in attitude depending on social status, and are considered to be maintained for a fairly long time. The feeding strategy of the lower-high class, in staying a longer duration in the artificial feeding area, and departing later, may be effective under the artificial feeding conditions, but it may be a bad strategy in a natural habitat where the food is not so clumped as in artificial feeding, and where choice of other food patches is possible. The above results agree well with previous reports for the Koshima group, indicating that the rank of the lower-high class females was unstable (Mori et al., 1989), and that their reproductive success was low (Watanabe et al., 1992).     

Despotic wild patas monkeys (Erythrocebus patas) in Kala Maloue, Cameroon

The socio-ecological model predicts that the quality, distribution, and patch size of food resources determines the dominance hierarchy of female monkeys based on the type of food competition they experience. Comparative studies of closely related species have evaluated the socio-ecological model and confirmed its validity. For example, female patas monkeys in Laikipia, Kenya, form a nonlinear and unstable dominance hierarchy (i.e., egalitarian), whereas females of sympatric, closely related savannah monkeys form a linear and stable dominance hierarchy (i.e., despotic), in accordance with the model's predictions of the characteristics of food resources. I compared agonistic interactions involving food between patas monkeys (Erythrocebus patas) and sympatric savannah monkeys (Cercopithecus aethiops) in Kala Maloue, Cameroon. I found linear dominance hierarchies not only in savannah monkeys, but also in patas monkeys in Kala Maloue. The rates of agonistic interactions during feeding between patas monkeys were equivalent to those between savannah monkeys in Kala Maloue; further, these rates were significantly higher than those of both Laikipia patas and savannah monkeys. The results imply that patas monkeys in Kala Maloue are not egalitarian, but are despotic, similar to savannah monkeys. Disparity in the dominance hierarchies of patas monkeys between Kala Maloue and Laikipia were attributable to the differences in the characteristics of food resources. Although patas monkeys in Laikipia subsist on small and dispersed food resources within a high-density area, those in Kala Maloue subsisted on food resources that were clumped in intermediate-sized patches within a low-density area. This study shows that the socio-ecological model is applicable not only for interspecific comparisons but also for intraspecific comparisons.     

Female social relationships in a captive group of Campbell's monkeys (Cercopithecus campbelli campbelli)

A study group of Campbell's monkeys (Cercopithecus c. campbelli) provided data on affiliative and agonistic relationships between females. Over a period of two years (involving 111 hr), we conducted observations of a captive group which had a composition similar to wild groups. We were able to identify a monitor-adjust social system with frequent affiliative interactions, directed gazing and avoidances rather than aggressive acts. We described long-term differentiated affiliative bonds: adult females interacting more often with some group mates than others, especially if they were relatives. Interactions between matrilines concerned essentially play and young adult females. We found a significant linear hierarchy of dominance with rare reversals and a stable intermatriline dominance. In contrast to other single-male groups, our adult male was socially integrated into the group although this may have been because of the housing conditions. Comparisons with the social organization of other captive and wild guenon groups are discussed.     

Individual participation in intergroup contests is mediated by numerical assessment strategies in black howler and tufted capuchin monkeys

Asymmetries in resource-holding potential between opposing groups frequently determine outcomes of intergroup contests. Since both numerical superiority and high intergroup dominance rank may confer competitive advantages, group members should benefit from assessing the relative strength of rivals prior to engaging in defensive displays. However, differences in individual assessment may emerge when cost–benefit trade-offs differ among group members. We examine the influence of numerical superiority and intergroup dominance relationships on individual participation in intergroup encounters in black howler monkeys (Alouatta pigra) and tufted capuchin monkeys (Sapajus nigritus). Black howlers responded with longer vocal displays during encounters with neighbours with an equal number of resident males, while tufted capuchins increased their participation with increasing relative male group size. Within each species, males and females responded similarly to varying numerical odds, suggesting that despite pay-off asymmetries between males and females, both sexes were similarly influenced by numerical asymmetries in deciding to participate in collective group defence. Whereas the outcome of contests among tufted capuchins was determined by relative male group size, reflected in a pronounced intergroup dominance hierarchy, the absence of dominance relationships among black howler groups may have provoked prolonged vocal displays in order to assess rival groups with matching competitive abilities.     

Longitudinal study of dominance relations among captive patas monkeys

Eight and a half years of dominance relations within a captive group of patas monkeys were analyzed. It was found that matrilineal kinship significantly influenced individuals' ranks. In contrast, with the exception of certain intramatriline changes, increasing age had no predictable effect on overall rank, at least for females (this was untestable for males). Offspring typically challenged maternal dominance and in eight of twelve dyads, offspring either rose fully over their mothers (three cases, all daughters) or at least achieved dominance ambiguity with them. Additionally, two of the four younger sisters with an opportunity to rise in rank over an older sister did so. The group dominance hierarchy was unstable for 75% of the study due to a combination of agonistically induced and demographically induced rank changes. Concentration of the highest ranks in a single matriline showed a stronger association with group hierarchy stability than did the presence of an adult, nonnatal male. Group hierarchy stability was associated with increased affiliation (sitting close and sitting touching), but otherwise there were no behavioral correlations. Individuals' ranks within the group hierarchy were unrelated to their chances of being wounded or having diarrhea. Adult females' ranks were over twice as stable as the group hierarchy (57.1% stability), but stability/instability was not correlated with any behavioral changes. Available evidence suggests that dominance relations play only a minor role in the organization of patas monkeys' intragroup behavior. Am. J. Primatol. 42:41–51, 1997. © 1997 Wiley-Liss, Inc.     

Initiation of feeding by provisioned patas monkeys: Evidence for the protection hypothesis

The applicability of the baboon-based protection hypothesis was tested with data from a provisioned, free-ranging group of Erythrocebus patas.The age/sex class of the individual which first approached and fed from one of the food hoppers during early morning feeding sessions was noted for 114 mornings. The presence of an observer, and periodically, rhesus monkeys,near the hopper made these approaches analogous to progressions described for feral baboons. Adult patas of both sexes approached and ate first significantly more frequently than was expected based on their respective proportions in the group, and immature monkeys less often. For adult females,initiating feeding was not correlated with dominance rank, although females in the middle and lower thirds of the hierarchy (n = 6 in each third) initiated feeding more frequently than did the females in the top third. The protection hypothesis accounts for the observed behavioral pattern, while explanations based on competitive exclusion and dominance relationships do not adequately account for the results.     

The First Description of Dominance Hierarchy in Captive Giraffe: Not Loose and Egalitarian,but Clear and Linear

Wild giraffes live in extensive groups in the fission fusion system, maintaining long social distances and loose social bonds. Within these groups, resources are widely distributed, agonistic encounters are scarce and the dominance hierarchy was reported in males only, while never deeply analysed. In captivity, the possibility to maintain inter-individual distances is limited and part of the resources is not evenly distributed. Consequently, we suggest that agonistic encounters should be more frequent, leading to the establishment of the dominance hierarchy. Based on the differences in resource-holding potential, we suggested that the rank of an individual would be affected by age and sex. Based on hypotheses of prior ownership, we tested whether rank was positively affected by the time spent in a herd and whether it was stable in adult females, which were present long-term in the same herd. We originally monitored four herds of Rothschild giraffes (Giraffa camelopardalis rothschildii) in Dvůr Králové zoo (n = 8), Liberec zoo (n = 6), and two herds in Prague zoo: Prague 1 (n = 8) and Prague 2 (n = 9). The Prague 1 and Prague 2 herds were then combined and the resulting fifth herd was observed over three consecutive years (2009, 2010, and 2011) (n = 14, 13, and 14, respectively). We revealed a significantly linear hierarchy in Dvůr Králové, Prague 2 and in the combined herd in Prague. Rank was significantly affected by age in all herds; older individuals dominated the younger ones. In females, rank was positively affected by the time spent in the herd and adult females in Prague maintained their rank during three consecutive years. This study represents the first analysis of the dominance hierarchy in the captive giraffe, and discusses the behavioural flexibility of the social structure in response to monopolisable resources in a captive environment.     

麋鹿发情期主要活动的时间分配及行为研究

本文报道麋鹿在白天主要处于休息状态,早晨、黄昏是它们的摄食时间;成年雌体中的各项活动频率未显示出有明显差异;但雄鹿与雌鹿之间在活动时间分配上有明显差异,而且,雄鹿中的统治者与被统治者之间也表现出有所不同。在攻击行为方面,群内表现出有不同的特权形式;而在交往行为中,发现较多的频次出现于相同性别、年龄和同一阶层中。     

Food Competition and Linear Dominance Hierarchy Among Female Chimpanzees of the Taï National Park

Dominance rank in female chimpanzees correlates positively with reproductive success. Although a high rank obviously has an advantage for females, clear (linear) hierarchies in female chimpanzees have not been detected. Following the predictions of the socio-ecological model, the type of food competition should affect the dominance relationships among females. We investigated food competition and relationships among 11 adult female chimpanzees in the Taï National Park, Côte d'Ivoire (West Africa). We detected a formal linear dominance hierarchy among the females based on greeting behaviour directed from the subordinate to the dominant female. Females faced contest competition over food, and it increased when either the food was monopolizable or the number of competitors increased. Winning contests over food, but not age, was related to the dominance rank. Affiliative relationships among the females did not help to explain the absence of greetings in some dyads. However comparison post hoc among chimpanzee study sites made differences in the dominance relationships apparent. We discuss them based on social relationships among females, contest competition and predation. The cross-site comparison indicates that the differences in female dominance hierarchies among the chimpanzee study sites are affected by food competition, predation risk and observation time.     

Time budgets ofMacaca mulatta

We measured the amount of time that 20 rhesus monkeys,Macaca mulatta, (four adult males, 10 adult females, four juvenile males, and two juvenile females) contained in two enclosed social groups devoted to 16 activities. For 14 of these 16 behaviors we found significant differences between age-sex classes. For 14 behaviors, there were also differences between individual monkeys. Twelve of the 16 activities showed significant diurnal variations. We discuss the relation between the use of time and social position, the adaptive significance of diurnal variation, and compare our data with that available for free ranging rhesus.     

A review of sexual initiating behavior by male and female cynomolgus monkeys and some species comparisons

The sexual initiating behavior of male and female cynomolgus monkeys (Macaca fascicularis) observed during standard laboratory tests is reviewed and compared with that of rhesus monkeys (M. mulatta) observed under identical conditions. Species differences in sexual behavior are related here to differences in habitat, sexual dimorphism, and the dominance gradient between the sexes. Compared with rhesus monkeys, cynomolgus monkeys appear to be more arboreal, less sexually dimorphic, and have a smaller dominance gradient between the sexes. They exhibit a facultative single-mount copulatory pattern rather than the serial mount pattern of the rhesus monkey. Female cynomolgus monkeys are less dominated than rhesus females by their male partners. Direct aggression between mates is more frequent and redirected aggression occurs less often than in rhesus monkeys. These behavioral differences affect the interpretation of changes in initiation rates that occur (1) during the menstrual cycle, (2) when females are ovariectomized and given hormone replacement treatments, and (3) when males are castrated and treated with androgens. We conclude that estradiol in the female and testosterone in the male increase the sexual motivation of both the treated and the untreated partner. Valid interpretations of changes in initiation rates depend on accurate and exclusive definitions of behavior and on a consideration of the behavioral context in which they are made.