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.     

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.     

Influence of availability of perches on the behavioral well-being of captive,group-living mangabeys

Environmental enrichment is expected to increase the well-being of animals. Changes in well-being can be measured by variations in behavioral patterns. This study reports on behavioral changes induced, in arboreal monkeys, by progressively increasing the number of perches, from none to five, in an “experimental cage.” A cage equipped with five perches was used as the control cage. The behaviors of a group of seven gray-cheeked mangabeys in the control cage and in the “experimental” cage were compared. A total deprivation of perches yielded an increase in aggressive behaviors and locomotion, and a decrease in cohesiveness. Placing perches progressively in the experimental cage restored the level of all the variables to levels found in the control cage. This restoration to control levels actually occurred only when the number of perches in the experimental cage was close or equal to that in the control cage. Therefore perches constitute a necessary feature of an adequate environment for mangabeys. We suggest that this restoration is a consequence of providing appropriate structure of the utilizable space for the monkeys. This structure might increase the control and the predictability that monkeys should have over social events. © 1996 Wiley-Liss, Inc.     

Evolution of SIVsm in humanized mice towards HIV-2

Through the accumulation of adaptive mutations, HIV-2 originated from SIVsm. To identify these evolutionary changes, a humanized mouse model recapitulated the process that likely enabled this cross-species transmission event. Various adaptive mutations arose, as well as increased virulence and CD4⁺ T-cell decline as the virus was passaged in humanized mice.     

Predation on mammals by the grey-cheeked mangabeyLophocebus albigena

Behavioral observations were made on a habituated group of grey-cheeked mangabeys (Lophocebus albigena) in the Dja Reserve, Cameroon, using 5-min scan sampling periods at 15-min intervals. On two occasions male mangabeys captured and fed on mammalian prey, a squirrel and a bushbaby. Although grey-cheeked mangabeys have been studied at several sites, these are the first observations of carnivory by them.     

Correlates of Intergroup Transfer in Male Grey-cheeked Mangabeys

We studied factors influencing intergroup transfer in male mangabeys (Lophocebus albigena) inhabiting 7 social groups in Kibale National Park over a 2-year period. The sample consisted of 40 males including 36 that we captured and marked during the study. Intergroup transfers are movements between groups that culminate in either long-term (dispersal) or short-term (visits) residency by males in the new groups. Both dispersers and visitors had a greater tendency to move into groups that contained higher numbers of estrous females than their prior group. Using averages of weekly group counts, we found a significant positive relationship between the number of estrous females in a group and the number of adult males in a group, but not between the number of nonestrous females and the number of adult males in the 7 study groups. There is no evidence that dispersal events were released by aggression. For a sample of males followed 2 mo before emigration, aggression did not increase just before emigration. Results suggest that spatiotemporal availability of estrous females is a major proximate factor influencing intergroup transfer in mangabeys. The results also suggest that dispersing males are more sensitive to relative numbers of estrous females than to measures of female availability such as operational sex ratio, socionomic ratio, and the number of excess females that take into account the potential for male-male competition.     

Threats to observers,keepers, visitors,and others by zoo mangabeys (Cercocebus galeritus chrysogaster)

The facial threats of ten captive golden-bellied mangabeys (Cercocebus galeritus chrysogaster) were categorized by object threatened. Adult males threatened more than did females except when the object was a nonhuman primate in a neighboring cage. Juvenile mangabeys threatened mainly in play within their own enclosures. Keepers and observers did not differ in frequency of being threatened by the mangabeys. Adult female mangabeys seemed more concerned with neighboring cages of nonhuman primates than were the juveniles and the males. Human visitors to the enclosures received by far the most threats of any targets, certainly far more than the observers and keepers. They were treated like interlopers. Keepers were treated like familiar conspecifics, observers like familiar neighbors. The implications of these findings for captive management of primates and for observational methods in behavioral primatology are discussed.