Patterns of Frugivory in Three West African Colobine Monkeys

We studied the comparative feeding ecology of three species of colobus (Procolobus badius, Procolobus verus, and Colobus polykomos) on Tiwai Island, Sierra Leone. We collected dietary data on each species by scan-sampling habituated groups. Because these groups were observed in the same study area during overlapping time periods, the confounding effects of temporal and spatial variability in food availability were reduced. Our results show that the annual diets of the two larger species (Procolobus badius and Colobus polykomos) include roughly equal proportions of fruits (including seeds), young leaf parts, and mature leaf parts, although P. badius had a greater intake of floral parts. Procolobus verus consumed almost no mature leaf parts, few fruits and seeds, and many young leaf parts. Colobus polykomos commonly fed from lianas. Seeds were the dominant fruit item eaten by all three colobus, and the fruits they selected were generally dull and non-fleshy, in contrast to the brightly-colored, pulpy fruits eaten by guenons. Leguminous plants contributed substantially to the diets of both the larger species, but comparisons with other African forest sites indicate that colobine biomass is not closely correlated with the abundance of leguminous trees in the forest. (Deceased)     

Scramble Competition Among <Emphasis Type="Italic">Colobus vellerosus</Emphasis> at Boabeng-Fiema,Ghana

We investigated the occurrence of scramble competition among Colobus vellerosus at Boabeng-Fiema, Ghana. If scramble competition had an impact on feeding efficiency among females, we expected a positive relationship between group size and the proportion of time spent feeding, day journey length, or home range size assuming resource availability is similar among the groups compared. We collected focal data on the feeding behavior of adult females and males over 11 mo (September 2000–August 2001) on 2 study groups: WW (n = 31–33 individuals) and B (n = 8–16 individuals). We also collected ranging data on group movements at half-hour intervals. The large group (WW1) had a significantly longer day journey length than the small group (B1), and females in the large group spent a significantly greater proportion of time feeding in the wet season, a period of low food availability, which suggests it may be a bottleneck period when food resources are scarce and Colobus vellerosus is close to being energy limited. The proximity data suggested females may be able to reduce or adjust for competition by having fewer neighbors when they feed and by spreading out when in a larger group. However, we found no relationship between home range size and group size or that females spent a greater proportion of time feeding than adult males did. Our results highlight the need to factor in differences in food availability when investigating scramble competition. Though equivocal, our results suggest scramble competition occurs among Colobus vellerosus, leading us to suggest there was a match with the potential competitive regime, i.e., food distribution.     

Predicting the Competitive Regime of Female <Emphasis Type="Italic">Colobus vellerosus</Emphasis> from the Distribution of Food Resources

We examined the spatial and temporal distribution of the foods of ursine colobus (Colobus vellerosus) at Boabeng-Fiema, Ghana as a means to predict the monopolizablity and usurpability of their food resources. Recent evidence suggests that food may not be limiting for folivorous primates, and that male sexual coercion may be a more important influence on folivore social organization. To address the question, we collected focal data on the feeding behavior of adult females and males over 11 mo (September 2000-August 2001) on 2 groups: WW (n = 31–33 individuals) and B (n = 8–16 individuals). We also conducted phenological monitoring and a tree survey of the two-group home ranges to establish food availability and distribution. We used 2 behavioral or organism-defined indicators of feeding behavior to assess potential resource contestability: food site residence time and distance moved between food sites. The colobus fed on a high diversity of species, most of their food trees were not clumped in distribution, within-tree interfood distances were short, and food trees were large. The only condition associated with the potential for monopolization was low food tree density. However, low food tree density may be offset by the colobus’ use of large trees. Taken together, the ecological and behavioral indicators suggest the food resources of Colobus vellerosus had a low potential for monopolization. Our results also indicate mature leaves had the longest food site residence time, which may suggest they should be the most usurpable plant part, though their presumed low quality and high abundance probably counteracted the effect. The pattern implied the potential for direct feeding competition among Colobus vellerosus at Boabeng-Fiema was low and agonistic interactions over food are not expected. Instead, a group size effect on feeding efficiency should be a more predominant influence on feeding efficiency, if food is limiting for the species.     

Fragmented living: Behavioural ecology of primates in a forest fragment in the Lopé Reserve, Gabon

A 17-month study was made of the primates using a 9-ha “island” of forest, surrounded by savanna, in the northern part of the Lopé Reserve, Gabon. One group ofCercopithecus cephus (plus a young maleCercopithecus nictitans who was in permanent association with them) were resident in the fragment and groups of five other species of primates made visits during 127 days of observation:Pan troglodytes, 15 visits;Cercocebus albigena, 10;Colobus satanas, 3;Cercopithecus nictitans, 2;C. pogonias, 1. Visits were also made by lone males of three species,C. nictitans, Cercocebus albigena, andMandrillus sphinx. The eighth species of diurnal primate present at Lopé,Gorilla g. gorilla, did not visit the fragment during the study. Compared to conspecific groups in neighbouring continuous forest, primates in the fragment ate less fruit, seeds and flowers and more insects and leaves. The local population density of primates resident in the fragment was equivalent to that of the neighbouring continuous forest where all eight species occur, despite the diversity and abundance of fruit being less in the fragment. The costs imposed on the resident group by the reduced diversity and availability of preferred fruit foods appeared to be offset by a number of benefits that increased individual feeding efficiency for monkeys residing within a single fragment. These included lower travel costs, reduced feeding competition between individuals through group fission, and excellent knowledge of the location and quality of food resources in the small home range. It is also possible that the overall negative impact of inter-specific feeding competition was lower in fragments than in continuous forest and that micro-habitat differences resulted in an increased availability of palatable insect and leaf fallback foods in the fragment.     

Census,habitat preference,and polyspecific associations of six monkeys in the Lomako Forest,Zaire

This paper reports preliminary data on a number of poorly known cercopithecids inhabiting the Lomako Forest, Zaire. Data include those on density, biomass, group size, the relationship between group type (mono vs. polyspecific) and forest type (mixed primary, secondary, monodominant primary, and swamp), and vertical stratification. Species examined are Colobus angolensis, Cercocebus aterrimus, Cercopithecus wolfi, Cercopithecus ascanius, Cercopithecus neglectus, and Allenopithecus nigroviridis. The density and biomass for the Lomako Forest anthropoids (excluding Cercopithecus neglectus and A. nigroviridis) are 165 ind/km² and 1,034 kg/km², respectively. Cercopithecus wolfi and Colobus angolensis are found in group sizes similar to those reported from other sites while Cercopithecus ascanius, Cercocebus aterrimus, and A. nigroviridis display group sizes unique to the Lomako. While Colobus angolensis, Cercocebus aterrimus, Cercopithecus ascanius and Cercopithecus wolfi were found, to varying extents, in all four forest types, Cercopithecus neglectus and A. nigroviridis inhabited only swamp forest. The different species sort out along vertical continua both within and between the four forest types. © 1994 Wiley-Liss, Inc.     

Diets of two sympatric colobines in Zaire: More evidence on seed-eating in forests on poor soils

Recent studies have shown that the so- called folivorous African colobines eat a significant amount of seeds. There is disagreement as to whether seed-eating is due to the poor quality of tree foliage, due in turn to poor soils, or to the fact that seeds are a normal part of colobine diets. To test these hypotheses, we studied feeding of red colobus monkeys, Colobus badius tholloni,and black-and-white colobus monkeys, Colobus angolensis angolensis,in a tropical rain forest of Central Zaire (Salonga National Park). We conducted studies on soil properties, vegetation composition, and the availability and chemical contents of food plants simultaneously. Soils were very acid, with a high percentage of sand, very low cation exchange capacity, and very low exchangeable bases. The forest was dominated by legumes (45.6% of trees), among which the Caesalpinioideae were the best represented (85%). C. badiusfed mostly on leaves (61%) and seeds (33%), legumes making up 65% of their diet. C. angolensisfed mostly on seeds (50%) and leaves (27%); 39% of their diet came from legumes. The two species tended to select items richer in crude protein or lipids or both. Total phenolics and condensed tannins were abundant in the foliage and seeds but were poor predictors of colobine choice of food. Intersite comparisons show that colobines in Zaire ate a higher proportion of seeds than all other related species so far studied in Africa and that the Salonga forest had among the poorest soils and harbored the highest percentage of Caesalpinioideae. Our results confirm that seed- eating is more common among colobines living in areas where soils are poor. They strongly suggest that this link is mediated through forest composition, especially the abundance of legumes, and that the development of seed- eating results both from the high availability of nutrient-rich seeds and from the poor quality of mature tree foliage.     

Differences Between Vervets (Cercopithecus aethiops) and Patas Monkeys (Erythrocebus patas) in Agonistic Interactions Between Adult Females

We examined agonistic interactions between adult females in wild, unprovisioned patas monkeys (Erythrocebus patas) and vervets (Cercopithecus aethiops). The dominance hierarchy of patas is far less clear than that of vervets. Patas had fewer interactions per dyad, fewer dyads with interactions, and a high percentage (18%) of reversals in which lower-ranking females won in agonistic interactions with higher-ranking females. Although the rank ordering of the kinds of interactions patas and vervets displayed is similar, with avoidance being the most frequently observed agonistic response to approaches by other females, patas were chased and supplanted more often than vervets were. The resources over which females were supplanted also differ between species. Supplants over food comprise smaller proportion of total supplants patas than for vervets. Patas appear to feed on less usurpable foods than vervets. We conclude that (1) Erythrocebus and Cercopithecus spp., except C. aethiops, should not be categorized with other Cercopithecinae, and C. aethiops should not be categorized with other Cercopithecus spp. and Erythrocebus, in discussions and analyses of relationships between females within groups and (2) ecological conditions, i.e., usurpability of foods, can override phylogenetic history as the selective pressure determining the nature of female competitive relationships within groups.     

Habitat,diet, and activity patterns of free-ranging woolly spider monkeys (Brachyteles arachnoides E. Geoffroy 1806)

Results of a 10-month study of the ecology and behavior of free- ranging woolly spider monkeys (Brachyteles arachnoides)in Brazil show that these animals are strongly folivorous. Leaf-eating accounted for more than 50% of the total feeding time in all samples but one and accounted for more than 80% of the total feeding time in three samples. Mature foliage was routinely eaten. Woolly spider monkeys consistently spend more than 50% of each day quietly resting and sleeping. Animals travel little except when actively feeding and show low levels of social interaction. Such an activity profile suggests that woolly spider monkeys may often be living near the limits of their energetic resources. The social organization of the species is unusual for a folivorous primate in that small groups of females and associated immature animals confine their activities to discrete home-range areas, whereas males are itinerant, traveling over the home ranges of various female groups. Animals sharing a common home-range area show no permanent daily pattern of association other than that of mother-dependent offspring. Foraging alone or with few conspecifics should maximize each individual’s returns from foraging by minimizing the day range that must be traveled each day to locate foods while simultaneously lowering interference competition for higher-quality dietary resources.     

Better to Live with Allogenerics Than to Live Alone? The Case of Single Male Cercopithecus pogonias in Troops of Colobus satanas

We report the integration of single male crowned guenons (Cercopithecus pogonias) into troops of black colobus (Colobus satanas). We observed one male Cercopithecus pogonias in three troops of Colobus satanas on 30% of observation days (n = 231). Activities of single males guenons did not differ significantly from those of the colobus with which they associated. Moreover, both species performed simultaneously the same activities more often than expected by chance. Interspecific grooming occurred on several occasions. Furthermore, single male guenons spent as much in time social activities when part of a colobus troop, as they typically do when part of a conspecific group. Unlike solitary male crowned guenons, which are silent, a male that is integrated into a troop of colobus is vocal and emits social alarm calls to which colobus monkeys respond. During the single file movements of colobus troops, single male crowned guenons were integrated in the core of the troop and used the same branches at the same height with the colobus. Thus, the life of a single male crowned guenon with black colobus was social. We suggest that the main benefits that he gained is the possibility to live in a social context. Social interactions could be the key element to explain why single males Cercopithecus pogonias join troops of monkeys so different from their natal groups.     

The cost of living in larger primate groups includes higher fly densities

Flies are implicated in carrying and mechanically transmitting many primate pathogens. We investigated how fly associations vary across six monkey species (Cercopithecus ascanius, Cercopithecus mitis, Colobus guereza, Lophocebus albigena, Papio anubis, and Piliocolobus tephrosceles) and whether monkey group size impacts fly densities. Fly densities were generally higher inside groups than outside them, and considering data from these primate species together revealed that larger groups harbored more flies. Within species, this pattern was strongest for colobine monkeys, and we speculate this might be due to their smaller home ranges, suggesting that movement patterns may influence fly–primate associations. Fly associations increase with group sizes and may thus represent a cost to sociality.

     

Diet and dominance among female vervet monkeys (Cercopithecus aethiops)

Behavioral observations of free-ranging female vervet monkeys (Cercopithecus aethiops) suggest that priority of access to food enhances individual fitness. Seventeen adult females living in two social groups were observed for 26 months in the Samburu/Isiolo Game Reserves, northern Kenya. Priority of access to feeding and sitting sites was associated with significant differences in diet and reproduction. Food species distribution altered rank-related differences in diet. Rank-related differences in diet occurred when food items were clumped in distribution, but not when they were randomly distributed. The relation of individual food items to reproduction influenced rank-related differences in reproduction. Rank was significantly correlated with birth rate when a preferred food species was clumped in distribution.     

Constraints on Group Size in Red Colobus and Red-tailed Guenons: Examining the Generality of the Ecological Constraints Model

The ecological constraints model proposes that an increase in group size will increase intragroup feeding competition and thereby constrain group size. Although this model has received wide acceptance, tests of it are based only on a few studies of species that have similar ecological requirements and social organizations, and there are reasons to question the widespread acceptance of the assumptions underpinning it. Via a 2-year study, we explored determinants of group size in species that feed on markedly different types of foods: the folivorous red colobus (Procolobus pennantii) and the frugivorous/insectivorous red-tailed guenon (Cercopithecus ascanius). We established 4 study sites approximately 15 km apart in Kibale National Park, Uganda, to examine the relationship between average group size and food availability. In both species, we quantified interdemic variation in diet, density of food trees, rate of travel, and group size. Red colobus at all sites relied heavily on leaf resources (75.5%–86.9%), but fruit (6.4%–13.9%) and flowers (2.0%–13.9%) were important in some populations. In general, red-tailed guenons fed on fruit (35.7%–59.7%), insects (14.5%–17.6%), and young leaves (12.2%–32.8%), but the amount of time allocated to these foods varied among sites. Average monthly density of trees bearing food items ranged among sites from 45 to 79 trees/ha for red colobus and from 19.6 to 67.3 trees/ha for red-tailed guenons. For both species, rate of travel was similar among sites, with one exception for red colobus. Average red colobus group size varied among sites from 14 to 40 (28 groups counted). Red-tailed guenon group size varied among sites from 11 to 24 (16 groups counted). As predicted by the ecological constraints model, group size increased with food tree density across sites for both species.     

Effect of Group Size on Activity Budgets of Colobus vellerosus in Ghana

Group size influences foraging efficiency in several primates. We examined the activity budgets of 3 groups of Geoffroy's pied colobus (Colobus vellerosus) at the Boabeng-Fiema Monkey Sanctuary in Ghana to determine whether larger group size induces scramble competition. We studied 2 groups (B1; N = 7-8 and WW; N = 31-33) occupying slightly overlapping home ranges from August to November 2000. We observed the third group, B2 (N = 15-16), comprising B1 and 7 male invaders in the same home range as B1 from August to November 2001. By comparing groups belonging to the same population and occupying sligthly overlapping or similar home ranges, we were able to control, to a certain extent, for differences in food distribution. We recorded a total of 3353 scans, yielding 14,886 activity records, over 73 days. As with other black-and-white colobus, resting was their most common activity (59%). Intergroup comparisons suggest that time spent feeding, resting and moving did not vary in relation to group size. However, intragroup comparisons between the sexes show that females in the large group spent more time feeding than males did, whereas this was not the case in the small group, which suggests that scramble competition may be occurring among female Colobus vellerosus at BFMS. It is also possible that this may be due to greater nutritional requirements because of a higher proportion of infants in the large group. In fact, the proportion is quite similar between the two groups, lending support to the idea that females in the two groups had comparable nutritional demands due to lactation. This suggests that increased feeding in females in the large group was partly an effect of scramble competition. Group size and group composition also influenced the frequency of social behavior. There was more grooming in the large group, and it was performed mostly by females. The distribution of activities throughout the day was similar to the pattern reported for other black-and-white colobus.     

Impact of Commercial Hunting on Monkey Populations in the Taï region,Côte d'Ivoire1

We studied the impact of hunting on monkey species in the Taï National Park and adjacent forests in Côte d'Ivoire. The average wild meat consumption per capita per year was assessed from market surveys and interviews. We determined that the amount of primate wild meat being extracted in the Taï National Park and surrounding forests was 249 t in 1999. Hunting pressure was the highest on the larger primate species such as red colobus, Procolobus badius, black and white colobus, Colobus polykomos, and the sooty mangabey, Cercocebus torquatus atys. Estimates of population densities were based on line transect surveys. The maximum annual production of each species was calculated using the Robinson and Redford model (1991) and assuming unhunted conditions. Comparing current harvest levels with the maximum sustainable yield suggests that harvest of red colobus monkeys (Procolobus badius) is sustainable, whereas current off‐take of the black and white colobus (Colobus polykomos), the sooty mangabey (Cercocebus atys), diana monkeys (Cercopithecus diana), and Campbell's monkeys (Cercopithecus campbelli) exceeds sustainability by up to three times.     

Interspecific interaction of the primate groups in Kibale Forest,Uganda

An ecological survey on the influence of interspecific interaction of the primates upon the distribution of their group ranges was carried out in 100 ha of the isolated forest northern outskirts of Kibale Forest in western Uganda, Africa. The study period of 105 days was from the 12th of November, 1970 to the 24th of February, 1971, including a preliminary survey of about two months. The subjects of this study are five species of primates, i.e., black and white colobus (Colobus polykomos), red colobus (Colobus badius), red tailed monkey (Cercopithecus ascanius), blue monkey (Cercopithecus mitis), and vervet monkey (Cercopithecus aethiops), which inhabited the study area. The red colobus group is thought to be the most influential of the five in the interspecific interaction.     

Effects of habitat disturbance on the behavioral ecology and demographics of the Tana river red colobus (Colobus badius rufomitratus)

Annual surveys in 1985–1987 revealed that, since 1975, the total population of the Tana River red colobus (Colobus badius rufomitratus)declined by approximately 80%. An intensive study in 1986–1988 of two groups of colobus in the Tana River Primate National Reserve indicated that habitat disturbance from the changing river course and shifting agricultural practices were primarily responsible for the decline. Clearcutting around Mchelelo forest in the late 1960s compressed colobus populations to levels probably above the carrying capacity. Between 1975 and 1986 primate population density declined dramatically, the number of red colobus groups in Mchelelo forest decreased by half, and the size of the remaining group was greatly reduced. In 1986, there were fewer solitary colobus and small parties in the forest, harem male takeovers did not occur, infant survivorship increased, and demographic parameters generally had improved. The colobus groups in Mchelelo in 1973–1975, living at higher densities, showed different feeding and ranging behaviors than 1986–1988 groups. Range size was smaller in 1975, range overlap occurred, and a greater portion of the forest was used per day and per month. Mature leaves accounted for a much higher proportion of the diet. Time spent feeding and resting was the same in both studies. Social organization in predominantly one- male groups was maintained and adult and subadult females transferred between groups.     

Optimal foraging strategies in the diet of the green monkey,Cercopithecus sabaeus,at Mt. Assirik,Senegal

The feeding behavior of one group of green monkeys (Cercopithecus sabaeus)was observed between October 1978 and December 1979 in the Parc National du Niokolo-Koba, Senegal. Details of the vegetational composition of the habitat and seasonal variation in food availability were also recorded. The green monkeys’ diet was omnivorous and diverse, including over 65 species of plants, many invertebrates, and some eggs and meat. Preference was given to fruits and flowers, although particular species were not selected; rather, these foods were eaten in proportion to their availability. Leaves, gum, seeds, and fungi were secondarily preferred foods, their consumption depending mostly on the availability of fruit or flowers. There was little overlap in the composition of the diet from month to month, reflecting the strong seasonality of the environment, although there was a consistent intake of invertebrates each month. Differences in diet between populations of the superspecies C. aethiopsare related to the floristic composition of the vegetation. Data on seasonal variation in the diet and changing patterns of resource availability are drawn together within the framework of optimal foraging theory to examine the adaptive strategies underlying the monkeys’ behavior. Their choice of diet was optimal in that they were more selective when profitable food items were common: higher proportions of the diet were given over to fruit and flowers when food availability was high. In parallel with this strategy, a nutritive balance was maintained by consistent inclusion of invertebrates and at least some foliage in the diet, regardless of the amount of fruit or flowers available.     

In Vitro Fermentation of Dietary Carbohydrates Consumed by African Apes and Monkeys: Preliminary Results for Interpreting Microbial and Digestive Strategy

Primates derive significant nutritional benefits from hosting symbiotic, fermenting microbes in their gut, including the provision of energy from short-chain fatty acids (SCFAs). We measured fermentation parameters in fecal samples of 4 hindgut fermenting species (Gorilla gorilla, Pan troglodytes, Papio hamadryas, Cercopithecus neglectus) and 1 foregut fermenting species (Colobus guereza) to determine whether differences in SCFA profiles exist between the 2 digestive systems. We analyzed SCFA profiles, culture pH, and methane from fecal samples collected at the North Carolina Zoological Park. Results indicate that the captive individuals exhibit high total SCFA concentrations, with a particularly high acetate-to-propionate ratio. Methane levels were highest in the 2 ape species, and lowest in Colobus guereza and Cercopithecus neglectus. Total SCFA concentrations were similar between wild and captive-born Gorilla gorilla, although concentrations of acetate were significantly greater —and butyrate concentration and methane production significantly lower— in wild-caught gorillas relative to captive-born. These results are consistent with data on diet and digestive retention times among Catarrhini and have implications for our understanding of the interactions among diet, body mass, digestion, and how monogastric cercopithecines can consume either similar or greater levels of fiber than larger-bodied apes.     

Behavior of bonobos (Pan paniscus) following their capture of monkeys in Zaire

For the first time, three cases of capture and forced interaction were observed between bonobos (Pan paniscus)and two other species of primates (Colobus angolensisand Cercopithecus ascanius)in the Lilungu (Ikela) region, Republic of Zaire. The bonobos interacted with the captured primates as if they were dealing with individuals of their own species. They sought cooperation in their interactions with the captured young primates without scccess. There is no evidence that they ate the captives.     

Nutritional ecology of Preuss's red colobus monkey (Colobus badius preussi Rahm 1970) in Korup National Park, Cameroon

Studies on the nutritive ecology of red colobus monkeys (Colobus badius preussi) in Korup National Park, Cameroon, investigated food plants and the parts eaten as well as nutritive values of the various food items. Food plants were identified through direct observations and collected for laboratory determination of nutrient content. Food plants were analysed for crude protein (CP), crude fibre (CF), ether extract (EE), nitrogen‐free‐extractive (NFE) and total ash (A). A total of seventeen species belonging to nine different families were identified as food plants for red colobus. Food and feeding habits showed that the species were highly folivorous, tending to prefer the young leaves of food plants. Lecomtedoxa klaineana (27.0%) and Xylopia aethiopica (22.2%) of families Sapotaceae and Annonaceae, respectively, constituted about 50% of total food items consumed. Results of nutrient composition indicated individual nutrients varied significantly (P < 0.01) with food species.