Patterns of male residency and intergroup transfer in gray-cheeked mangabeys (Lophocebus albigena)

We describe the movements and fates of 36 collared gray-cheeked male mangabeys (Lophocebus albigena) that resided in seven social groups in Kibale National Park, Uganda. The male mangabeys were captured, radiotagged, and then contacted regularly over a period of up to 8 years. Individuals varied considerably in how tightly they were associated with their groups. "Central" males were usually found in close spatial association with their own groups, but they sometimes visited others. "Peripheral" males were often found several hundred meters away from their own groups. Most adult males were characterized by repeated intergroup transfers, manifested as "visits" and "dispersals." Visits were transfers that did not result in mating. The visits were brief, and ranged from a few minutes to a few days before the male returned to his previous group, moved on to another group, or returned to solitary life. The term "dispersal" refers to a transfer that results in mating, after which the male remains in the new group. Young males began to drift away from their natal groups in early subadulthood, but the timing of first associations with estrous females in other groups was highly variable. Natal dispersers were generally solitary for a month or more, and at least half moved into nonadjacent groups. Secondary dispersal was common. After they immigrated, adult males remained in a group for a median of 19 months before they emigrated again, with the probability of departure being approximately constant in time. Secondary dispersal was usually made into an adjacent group and lasted less than 7 days. Emigration and immigration were not seasonal, and males emigrated singly and apparently independently; however, immigrations were clumped in time, and male dispersal contributed to considerable heterogeneity of group composition. L. albigena dispersal patterns are intermediate between those described for Papio baboons and forest Cercopithecus, and models that predict demographic consequences of dispersal for baboons can be refined to apply to mangabeys.     

An assessment of gum-based environmental enrichment for captive gummivorous primates

In the wild, many primates consume gums exuded from trees, and many species are gum specialists. In spite of this, few data exist concerning gum feeding in captivity. Using a web-based survey of 46 zoos in 12 countries, we evaluated the extent to which zoos feed gum to primates. We found that although callitrichids and galagos receive gum-based enrichment, cercopithecines generally do not. Environmental enrichment is important for stimulating naturalistic behavior to promote the psychological wellbeing of animals. Thus, gum-based enrichment is important for captive gummivores. Our study highlights the need to improve environmental enrichment for captive gummivores, in particular that of cercopithecines. This is most striking for the patas monkey (Erythrocebus patas), an obligate gummivore. The exchange of ecological data between field research and captive settings is crucial, and is just one way primate caretakers can contribute to the conservation and welfare of some of our closest living relatives.     

Seed-eating by West African cercopithecines, with reference to the possible evolution of bilophodont molars

Data on tooth use in eating fruits and seeds were collected on 12 West African monkeys representing five species of cercopithecines, Cercopithecus aethiops, Cercopithecus campbelli, Cercocebus atys, Erythrocebus patas, and Papio papio. Field observations and information in the published literature were used to select fruits for captive feeding trials. A total of over 27,000 tests were conducted to determine the preferences of the monkeys for 78 fruits. Data were collected on the selection of fruit parts, as well as tooth use, in eating 88 fruit species. All five monkey species had remarkably similar fruit part preferences. Seeds were eaten in 86% of the tested fruits and represent the fruit part most frequently eaten by all the tested monkeys. With few exceptions, molars were used to puncture and crush the seeds. It is suggested that the development of bilophodont molars might be an adaptation by Old World monkeys to seed predation. Given their large size relative to other arboreal frugivores, seed predation could provide a dietary niche for Old World monkeys.     

Red-Tailed Guenons (Cercopithecus ascanius) and Strychnos mitis: Evidence for Plant Benefits Beyond Seed Dispersal

I report data collected on red-tailed guenon (Cercopithecus ascanius schmidti) fruit processing behaviors between June 1993 and April 1994. Red-tailed guenons consumed the fruit of Strychnos mitis in 542 of 2,930 fruit-eating events (FEEs). The monkeys spat out cleaned seeds of Strychnos mitis in a majority of these records (477/542; 88%); seeds were occasionally swallowed whole, but only when pulp was unripe (69/542; 12%). In 83% of the FEEs on Strychnos, the red-tailed guenons spat out seeds within 10 m of the removal site; they typically stayed in the same tree while processing fruit, and in 56% of the FEEs, they moved <1 m before spitting seeds. I monitored spat seeds to evaluate the impact of monkey fruit processing on seed fate. Results indicate that 83% of seeds spat out by the red-tailed guenons germinated, while only 12% of unprocessed seeds survived to germination (p < 0.01). Of the processed seeds that germinated, 60% survived to germination and seedling establishment, while only 5% of unprocessed seeds survived to seedling establishment (p < 0.01). Unprocessed seeds were also more likely to be attacked by seed predators (p < 0.01) and fungus (p < 0.01). Although there is generally high mortality in seeds/seedlings, mature trees of Strychnos mitis are found in groves of adults, under which dense populations of seedlings and saplings can occur. These data suggest that Strychnos mitis does not conform to expectations of the Janzen-Connell model of seed escape from parent trees. Instead, I suggest that by removing pulp, a process that results in a reduction of fungal pathogen attack, red-tailed guenons positively effect the seed survivorship of Strychnos mitis. Although this effect has been observed in pulp-cleaning ant species, it is a hitherto undescribed effect of primates on their fruit resources.     

Dental morphometric variation between African and Asian colobines, with special reference to the other Old World monkeys

In order to reveal differences between Asian and African colobines (nonhuman primates) in terms of dietary adaptation and evolutionary development, a large number of the species of the cercopithecoids (Old World monkeys) was analyzed with morphometric methods. In addition to the raw data and ratios, deviations of the colobines, predicted from allometric baselines derived from the cercopithecines, were analyzed by univariate and multivariate analyses. Some results indicated that there exists significant differentiation between colobines and cercopithecines; the latter exhibit a larger dental scale relative to body size, and the less developed front teeth of the colobines may be related to their fewer frequent incisal use, compared with those of the cercopithecines. With regard to variations between the two subtribes of the colobines, which are found in African (Colobina) and Asia (Presbytina), the Asian subtribe displays a larger scale of postcanine teeth, referring to the results of the raw data. This may correspond to their larger body size. While ratios were considered, the variation between Presbytina and Colobina was diminished greatly. This implies that, unlike the scenario postulated to reflect the relationships between colobines and cercopithecines--which supposes that their differentiation is in both size and shape--the variation between the two subtribes is principally size associated: relative to body size Colobina exhibits more emphasized incisors, but less developed postcanine teeth--with the exception of width of M3s. In other words, the relationships between teeth and body size of the African colobines are more similar to those of the cercopithecines. This implies, compared to their Asian partners, that African colobines share more similarities with cercopithecines. This may be related to the episodes in which African species underwent a longer period of sharing environmental and climatic patterns with the cercopithecines that moved to Asia about 5 or 8 million years ago. Canines were found to be important in distinguishing colobines from cercopithecines and in separating one subtribe from the other.     

Secondary sex ratios by maternal rank,parity, and age in captive rhesus macaques (Macaca mulatta)

Analysis of 645 conceptions by captive rhesus macaques (Macaca mulatta) with known reproductive histories indicated that maternal age and parity had little effect on the sex of progeny. There was, however, a slight indication that high-ranking females produced a higher proportion of daughters and relatively fewer sons than did low-ranking females. These results provide only weak support for the “advantaged daughter” hypothesis suggested by three previous studies of cercopithecine monkeys, and therefore they further confound the conflicting results for macaques and baboons in general.     

Social structure,infant handling,and mothering styles in group-living old world monkeys

I argue that in Old World monkeys, infant handling by individuals other than the mother is a heterogeneous phenomenon in structural and functional terms; species differences in maternal tolerance of infant handling are related to differences in the relative proportion of abusive to affiliative responses made to infants by adult females other than the mother; and infant handling by adult females is related to the species-typical social structure, with particular reference to social relationships among females and patterns of food competition. I apply the proposed relationship among social structure, infant handling, and mothering style to explain the observed variation in mothering styles between and within the subfamilies Colobinae and Cercopithecinae.