A brief report on the social behavior of the crested mangabey (Cercocebus galeritus galeritus) with a comparison to the sooty mangabey (C. torquatus atys)

A group of 38 free ranging crested mangabeys in the Tana River Primate Reserve was studied over a 6-week period for a total of 209.5 hr and behavioral comparisons made to a captive group of sooty mangabeys. Although quantitative comparisons between these two mangabey species are not possible, the present data suggest that these geographically separated mangabeys share several behavioral similarities. Copulatory behavior in both species involved a pattern of female darting and female vocalizing following the mount by the male. Several similarities in agonistic behavior also existed: 1) The victim often returned or stayed within 1 m of the aggressor following an agonistic episode; 2) retaliation in which the victim first fled or avoided the aggressor, then subsequently, chased or lunged at the aggressor, typically while screaming; and 3) frequent redirection of aggression by the victim following an agonistic episode. A dominance rank reversal occurred between the two adult male crested mangabeys with no severe wounding. The rank reversal seemed to be related to two subsequent behaviors which included infant carriage by the deposed alpha in the presence of the new alpha male and female demonstrations of extreme protectiveness of their infants in the presence of the new alpha male. Both of these behaviors have been reported in the sooty mangabey group.     

Familiarity and dominance relations among female sooty mangabeys in the Taï National Park

Dominance relationships of female sooty mangabeys have thus far been studied exclusively in captive groups. In captivity, adult females form a stable linear hierarchy as would be expected in species exhibiting strong contest competition. However, the same individuals do not exhibit other aspects of behavior that would be expected where contest competition occurs. For example, they show no kin‐based alliances leading to hierarchies in which the members of each matriline occupy adjacent ranks. The goal of this study was to provide the first data on dominance relationships of sooty mangabey females in their natural environment in the Taï National Park, Ivory Coast. In our study group, adult females formed a linear dominance hierarchy. Aggression over food increased in food patches, as would be expected for species that experience contest competition. Moreover, females formed highly differentiated social relationships, showing particular affinities with females of adjacent rank. Am. J. Primatol. 56:137–153, 2002. © 2002 Wiley‐Liss, Inc.     

Food competition in captive female sooty mangabeys (Cercocebus torquatus atys)

We studied the social and foraging behavior of two captive groups of sooty mangabeys under two different spatial food situations. These food conditions were clumped (food was placed in a box) and dispersed (food was dispersed over the entire enclosure). In each group five adult females and two adult males were observed. As a criterion for food competition, individual differences in the relative food intake were used. Adult female mangabeys had a linear, stable, and unidirectional dominance hierarchy. Access to food was rank dependent among females only under clumped food distribution, as current models of the evolution of primate social systems predict. However, feeding success appeared to be mediated not by female but by male agonistic behavior toward females. High-ranking females received relatively less aggression from males and could, therefore, stay and feed longer in the feeding area. Male tolerance of higher-ranking females seems to mediate female feeding success under restricted food resources. The establishment of a special relationship with a high-ranking male might, therefore, be a strategy to get better access to food. This study demonstrates that female competition for access to food should not be analyzed separately from male influences on females and suggests that a more integral role of males in socioecological models of the evolution of primate social systems should be considered.     

The structure and patterns of support in the encounters of the brown macaque (Macaca arctoides)

Aid and cooperation in agonistic encounters have been studied in two groups of stumptail macaques keeping in the open-air cages of nature type. The basic agonistic ranks are found and the cases of aid in encounters are classified. A quantitative analysis using the coefficient reflecting the individual rank, kin and frequency of different aids is carried out. The existence of mechanisms of aggression removal within group is revealed, the role of individual ranks and kin in keeping stability in group is shown.     

Attacks on neonates by a male mangabey (Cercocebus atys)

Aggressive behavior by an adult male toward selected infants and their mothers was observed during a long-term study of reproduction in a captive social group of sooty mangabeys (Cercocebus atys). The highest-ranking adult male in this group was observed to attack and bite three neonates out of a total of 13 infants born in 1982. All three attacks were directed attacks in which infants were grabbed from their mothers and bitten in the head. The first infant was fatally injured; the other two probably would have sustained fatal wounds had the male's canines not been blunted beforehand and had observers not intervened. The attacks were preceded by a pattern in which the male persistently stalked or chased the mother-infant pairs, a behavior first observed in the hours immediately following parturition. Unlike attacks in wild baboon groups following male immigration, these attacks on infants occurred in a stable social group in which the male attacker had been a lifelong resident. This male, however, had gained alpha rank only 3 months before attacking the first infant. These attacks, in the context of other evidence of aggression and wounding, are discussed relative to current models of infanticide in primates.     

Agonistic aiding: Kinship,rank, age,and sex influences

An analysis of 3,774 episodes of agonistic aiding collected during a two-year study of a rhesus monkey group (Macaca, mulatta) indicated the differential influence of kinship and rank relationships on the participation of different age-sex classes in both aid to victims and aid to aggressors. Most aiding favored victims rather than aggressors and was much more likely to occur when matrilineal kin were involved. Females were more likely to aid than were males, and the frequency of their participation increased with age. Females were much more influenced by kinship than were males and defended or aggressively supported kin against any third party regardless of dominance relationships. Adult males seldom aided against animals that were dominant to themselves; the rare exceptions occurred when adult males defended kin. Aiding was far more likely to occur if the victim was squealing, and noisy agonistic episodes often involved multiple aiders on both sides. Aiding patterns had some potential to insure dominance rank inheritance within families, in accordance with the Kawamura hypothesis. In aiding animals outside of their own matrilines, however, group members aided randomly with respect to this model. There was little evidence that aiding functioned to support individuals when they targeted animals to which they should be dominant as adults based on matrilineal dominance relationships. Most defensive aiding seemed to function primarily to defend victims (primarily kin) of aggression. Aggressive support of the attacker, on the other hand, seemed to function primarily to reinforce coalitions with the attacker. The identity of the victim was unimportant as long as it was neither kin to nor dominant to the aider. Aggressive support of attackers did not overturn existing dominance relationships.     

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.     

Infant carrying by adult male mangabeys (Cercocebus atys)

Sixty-five interactions where an adult male carried an infant in the proximity of a second male were observed during a 19-mo period in a captive sooty mangabey (Cercocebus atys) social group. The behavior was distributed nonrandomly in both the adult male and infant classes. In all but three of the interactions, the recently deposed alpha male carried an infant in the presence of the newly ascendant dominant male. In the first phase of the study, infants that were carried included the entire unweaned infant cohort (n = 5) born before the rank reversal. The rate of carrying in this class declined as a function of increasing infant age and time since the rank reversal. Infant carrying was not observed in the context of fighting, which was rare, and intermale aggression never preceded the behavior. However, in 40% of the cases, carrying occurred after an infant had been threatened by the dominant male. These results suggest that infant carrying served to protect the infant from aggression rather than to exploit the infant as an agonistic buffer. The data did not unequivocally support the postulate that carrying may be a form of paternal care since paternity could not be assessed. The similar structural and contextual patterns of infant carrying in this species suggest a common origin for triadic male-infant interactions in mangabeys and baboons.     

Function and distribution of coalitions in captive bonobos (Pan paniscus)

We examined the distribution of support behaviour within a captive group of bonobos. Most support was evoked by inter-sexual conflicts with the two highest ranking females. Within a dyad, the usual winner was most often supported. Individuals that challenged the rank order by aggressions and pestering were aggressed more often by their targets in the company of an ally. The two lowest ranking males served as scapegoats, receiving 80% of the contra-support. In coalitions, inviduals did not aggress victims they would not dare to attack without supporters. However, the victims of coalitions reacted more strongly with fear and rarely counteraggressed than when being attacked alone, indicative of the high impact of aggression in support. The alpha female showed some control behaviour when intervening in conflicts. The data fitted with several functional hypotheses: coalitions functioned to maintain existing ranks, to acquire ranks, to reduce tension, and to test or strengthen the bond. We suggest that support behaviour fulfilled a crucial role in the maintenance of the power of the two highest ranking females over the males. Among the females themselves the dominance relationships were not based on coalitions, but on individual attributes.     

Dominance hierarchy and social relationships in a group of Captive black-and-white snub-nosed monkeys (Rhinopithecus bieti)

Different types of dominance hierarchies reflect different social relationships in primates. In this study, we clarified the hierarchy and social relationships in a one-male unit of captive Rhinopithecus bieti observed between August 1998 and March 1999. Mean frequency of agonistic behaviour among adult females was 0.13 interactions per hour. Adult females exhibited a linear hierarchy with a reversal of 10.9%, indicating an unstable relationship; therefore, R. bieti appears to be a relaxed/tolerant species. The lack of a relationship between the agonistic ratio of the adult male towards adult females and their ranks indicated that males did not show increased aggression towards low-ranking females. Differentiated female affiliative relationships were loosely formed in terms of the male, and to some extent influenced by female estrus, implying that relationships between the male and females is influenced by estrus and not rank alone. A positive correlation between the agonistic ratio of adult females and their ranks showed that the degree to which one female negatively impacted others decreased with reduction in rank. Similarly, a positive correlation between the agonistic ratio of females and differences in rank suggests that a female had fewer negative effects on closely ranked individuals than distantly ranked ones. These data indicate that rank may influence relationships between females. A steeper slope of regression between the agonistic ratio and inter-female rank differences indicated that the extent of the power difference in high-ranking females exerting negative effects on low-ranking ones was larger during the mating season than the birth season, suggesting that rank may influence the mating success of females.     

Patterns of coalition formation by adult female baboons in Amboseli, Kenya

Coalitionary support in agonistic interactions is generally thought to be costly to the actor and beneficial to the recipient. Explanations for such cooperative interactions usually invoke kin selection, reciprocal altruism or mutualism. We evaluated the role of these factors and individual benefits in shaping the pattern of coalitionary activity among adult female savannah baboons, Papio cynocephalus, in Amboseli, Kenya. There is a broad consensus that, when ecological conditions favour collective defence of resources, selection favours investment in social relationships with those likely to provide coalitionary support. The primary features of social organization in female-bonded groups, including female philopatry, linear dominance hierarchies, acquisition of maternal rank and well-differentiated female relationships, are thought to be functionally linked to the existence of alliances between females. Female savannah baboons display these characteristics, but the frequency and function of their coalitionary aggression is disputed. In our five study groups, 4-6% of all disputes between females led to intervention by third parties. Adult females selectively supported close maternal kin. There was no evidence that females traded grooming for support or reciprocated support with nonkin. High-ranking females participated in coalitionary aggression most frequently, perhaps because they derived more benefits from group membership than other females did or could provide support at lower cost. Females typically supported the higher ranking of two contestants when they intervened in disputes between subordinates, so most coalitions reinforced the existing dominance hierarchy. Results indicate that female baboons participate in coalitionary aggression in a manner strongly influenced by nepotism and individual benefits.     

Long-term changes in dominance ranks among ring-tailed lemurs at Berenty Reserve, Madagascar

A study was conducted between 1989 and 2001 to monitor changes in the dominance ranks among adult ring-tailed lemurs (Lemur catta) at Berenty Reserve, Madagascar. Adult females were observed to be dominant over adult males. Their rank fluctuated greatly. However, in some troops, female rank orders were fairly stable over a period of several years. In general, male ranks were more unstable than female ranks. Most young females aged 3 years occupied the lowest ranks among adult females. However, several were also observed to have attained relatively higher ranks, placing them right beneath their high-ranking mothers; this suggested the existence of dependent ranks. Mothers were dominant over their daughters. Similarly, older sisters were usually dominant over younger sisters. The mean duration of alpha status for females was 1.95 years, although considerable variation was observed in the duration of the alpha status (1–5 or more years). Most young males aged 3 years initially occupied the lowest ranks in their natal troops, and then they migrated to non-natal troops around the age of 4 years. They ascended in rank between the ages of 4 and 6 years, although there was considerable variation in the acquirement of high rank. The mean duration of alpha status for males was 2.2 years. Larger males were observed to occupy higher ranks. Occasionally, both males and females showed intense aggression (i.e., targeting aggression) towards others.     

Grooming,rank, and agonistic support in tufted capuchin monkeys

Studies investigating the relation between allogrooming and social rank in capuchin monkeys (genus Cebus) have yielded inconsistent results. In this study, we investigated the relation between grooming, agonistic support, aggression and social rank in a captive group of tufted capuchin monkeys (C. apella). Differently from most previous studies, we based our analyses on a relatively large database and studied a group with known genealogical relationships. Tufted capuchin females did not exchange grooming for rank‐related benefits such as agonistic support or reduced aggression. Coherently with this picture, they did not groom up the hierarchy and did not compete for accessing high‐ranking grooming partners. It is suggested that a small group size, coupled with a strong kin bias, may make the exchange of grooming for rank‐related benefits impossible or unprofitable, thus eliminating the advantages of grooming up the hierarchy. We provide several possible explanations for the heterogeneity of results across capuchin studies that have addressed similar questions. Am. J. Primatol. 71:101–105, 2009. © 2008 Wiley‐Liss, Inc.     

Paternity in Sooty Mangabeys

We determined paternity for 78 sooty mangabeys [(Cercocebus torquatus atys (Groves, 1978) equivalent to C. atys (Napier and Napier, 1967)], born between 1986 and 1993, using DNA profile analysis. The analysis is based on two independent assays of the genome of each individual via multilocus DNA probes. The mangabeys were members of either a large (n = 98) or a small (n = 18) group. Overall, during two periods of analysis in the large group, higher-ranking males sired more offspring than their lower-ranking counterparts did, though during one period the correlation between dominance rank and reproductive success is not significant. Of the two males in the small group, the alpha male sired all of the offspring during one period. There is a significant correlation between mounts and the number of surviving offspring each male sired in one birth year. Moreover, the same male did not always sire the offspring of a given female from year to year. Behavioral data focusing on male–offspring interactions show that offspring (n = 15) did not preferentially affiliate with their sire and that males affiliated with infants too infrequently for analysis. Thus, in a large sooty mangabey colony: (1) dominance rank generally predicts reproductive success; (2) adult males are not preferentially attracted to their offspring, or infants to their sires; and (3) the same male generally does not sire the offspring of a given female from year to year.     

Seasonal rank changes for adolescent and subadult natal males in a free-ranging group of rhesus monkeys

Changes in dominance rank for adolescent and subadult natal males in a semi-free-ranging rhesus macaque group were seasonal. Three 4-year-old natal males of the highest-ranking matriline occupied high ranks in the adult male dominance hierarchy during the premating period. In the mating season they dropped in rank, and this decrement was related to a concomitant drop in their alliances. After the mating season, these males rose in rank along with their two 3-year-old kin to occupy ranks 2–5 and 7–8 in the adult male dominance hierarchy. Three-year-old natal males of matrilines lower ranking than first did not become integrated into the hierarchy at this time.     

Grooming, social bonding, and agonistic aiding in rhesus monkeys

An analysis of simultaneous grooming bouts in a captive group of rhesus monkeys (Macaca mulatta) failed to provide evidence of competition to groom high ranking partners. Not only were grooming supplantations rare, but the highest ranking individuals performing grooming did not groom the highest ranking animals receiving grooming. Lower ranking partners, however, did more grooming in nonkin dyads. Grooming partners aided one another in agonistic episodes, but the individual receiving the aid did not groom the individual providing the aid more than vice versa. Kin dyads did aid and groom one another at greater than expected rates, but the aider did not receive the greater proportion of grooming in the dyad. Males participated in more grooming than expected, but their grooming was not related to aiding either with regard to one another or female partners. Animals that were targeted in joint aggression, or aided against, received significantly less grooming from their opponents. A general social relationship expressed in partner preferences, social grooming, and agonistic aiding better explained the observed pattern than any model based on the exchange of services for favors in different currencies.     

Affiliative behavior of adult female sooty mangabeys (Cercocebus atys)

A 14-month study of 30 adult female members of a captive group of sooty mangabeys investigated their affiliative interactions with group members of varying age and sex. The adult females preferentially affiliated with other adults and interacted less than expected with immature group members. Dyadic frequencies suggested especially frequent affiliation with the three resident adult males, although the pattern of interaction with each male was distinct and apparently was related to age and dominance status of the males. Females of the alpha matriline showed significantly greater affiliation with the males than did those of other matrilines, but this preference was not reciprocated by the males. A preference for grooming older group members (some of the matriarchs and the oldest adult male) was also suggested. In consideration of the taxonomic distinctness of the sooty mangabey from the gray-cheeked mangabey, comparison of these results with those available for albigena were made. Few differences were apparent. Comparisons with the affiliative behavior of Papio females also suggested limited differences, despite the apparently isolated position of the sooty mangabey within the tribe Papionini.     

Absence of strongly kin-preferential behavior by adult female sooty mangabeys (Cercocebus atys)

The objective of this study was to test the hypothesis that kin-preferential behavior would be present in sooty mangabeys (Cercocebus atys), a species taxonomically close to baboons and macaques. The affiliative behavior of the adult female members of a large captive group of these mangabeys was analyzed to test this prediction. These females groomed, were approached by, were in proximity to, and were in contact with their kin significantly more than expected, but only when all kin were included in the analysis. Removal of only the mother-infant (less than 1 year) dyadic interactions removed all significant kin effects. Kin-preferential behavior was also absent in affiliative interactions among the adult females as a class. Affiliation between mothers and offspring significantly exceeded that for all other kinship categories (such as siblings, etc.), and affiliation with kin other than offspring did not differ from that with nonkin adults. In their interactions with nonkin, the adult females showed some preference (duration of grooming) for those adult females of similar age, an effect predicted by the intensity of interaction among members of the same age cohort during development. These similar-aged females may also be paternally related. In comparing these results with the existing literature on kin-preferential behavior, two conclusions may be reached: (1) age and degree of kinship are primary factors that must be considered in order to avoid the existing overgeneralization of the importance of kinship in primate social organization, and (2) the role and importance of affiliative behavior in kin-selection theory should perhaps be re-examined in light of questions raised by this study.     

Spoiled Brats: Is Extreme Juvenile Agonism in Ring‐Tailed Coatis (Nasua nasua) Dominance or Tolerated Aggression?

Ring‐tailed coatis exhibit an extreme form of juvenile agonism not found in other social mammals. Two groups of habituated, individually recognized, coatis were studied over a 2.5‐yr period in Iguazu National Park, Argentina. Dominance matrices were divided by year and group, resulting in four dominance hierarchies which were analyzed using the Matman computer program. Strong general patterns were seen in both groups during both years. Adult males (one per group) were the highest ranking individuals, followed by male juveniles, female juveniles, adult females, and male and female subadults. The pattern in which young, physically inferior individuals were able to outrank larger adults is different from other social mammal species in that the juvenile coatis aggressively defended food resources and directed aggression towards older individuals. These agonistic interactions may not reflect ‘dominance’ in the traditional sense, and appear to be a form of ‘tolerated aggression.’ This tolerated aggression leads to increased access to food, and should help juveniles during a period in which they need to rapidly gain weight and grow. Because this tolerance of juvenile aggression is reinforced through coalitionary support of juveniles by adult females, agonistic patterns are also consistent with the hypothesis that juvenile rank is being influenced by high degrees of relatedness within coati groups. Although some interesting parallels exist, there is little evidence indicating that these dominance patterns are the same as those found in other social mammals such as hyenas, lions, meerkats, or Cercopithicine primates.     

Incident of intense aggression by chimpanzees against an infant from another group in Mahale Mountains National Park,Tanzania

We document here an unusual case of intense aggression against an infant male from another group by chimpanzees (Pan troglodytes schweinfurthii) of the Mahale Mountains National Park, in Tanzania. Adult males of the study group collectively attacked an unknown male infant. Although an unknown female, probably the mother, tried to retrieve him, the infant was seriously injured and most likely died. During this incident, the unknown female attacked and injured two researchers. After the aggressive encounter, it was found that six of the nine adult males in the study group were wounded. Attacking the extragroup male infant may have the effect of weakening the future power of the neighboring group, leading to better access to resources and enhanced safety in the future for the study group.