Procolobus Verus Research Articles

Masticatory and ingestive effort in Procolobus verus, a small-bodied African colobine.

The olive colobus (Procolobus verus) is the smallest extant colobine. Based on the axiom that folivory is associated with larger body mass, the olive colobus is expected to be less folivorous than its sister taxon Piliocolobus badius, but previous studies show that the opposite is true. Here we test the hypothesis that masticatory and ingestive effort in the olive colobus is greater due to allometric factors related to bite force scaling and throughput of ingested foods. We analyzed oral processing data collected on olive colobus in the Taï Forest, Ivory Coast, between May 2016 and May 2018. We compare these with previously published data on P. badius and Colobus polykomos from Taï. In terms of overall feeding effort, olive colobus invest more effort (i.e., chewing cycles) than the larger colobines. When contrasts are restricted to commonly consumed foods, this greater energetic investment is not consistently observed. Ingestion of young leaves is associated with a reduced number of masticatory cycles in all three colobine species. A slightly elevated average effort in the olive colobus during young leaf feeding suggests this food source is more challenging in smaller monkeys, but mature leaf processing effort is generally the same among Taï colobines. Thus, for olive colobus, leaf ductility may be more problematic than leaf toughness in terms of masticatory effort. While there may be an allometric cost to being a small colobine, food selectivity is an important mitigating factor.

Enamel chipping in Taï Forest cercopithecids: Implications for diet reconstruction in paleoanthropological contexts

Antemortem enamel chipping in living and fossil primates is often interpreted as evidence of hard-object feeding (i.e., ‘durophagy’). Laboratory analyses of tooth fracture have modeled the theoretical diets and loading conditions that may produce such chips. Previous chipping studies of nonhuman primates tend to combine populations into species samples, despite the fact that species can vary significantly in diet across their ranges. Chipping is yet to be analyzed across population-specific species samples for which long-term dietary data are available. Here, we test the association between enamel chipping and diet in a community of cercopithecid primates inhabiting the Taï Forest, Ivory Coast. We examined fourth premolars and first molars (n = 867) from naturally deceased specimens of Cercocebus atys, Colobus polykomos, Piliocolobus badius,Procolobus verus, and three species of Cercopithecus. We found little support for a predictive relationship between enamel chipping and diet across the entire Taï monkey community. Cercocebus atys, a dedicated hard-object feeder, exhibited the highest frequencies of (1) chipped teeth and (2) chips of large size; however, the other monkey with a significant degree of granivory, Co. polykomos, exhibited the lowest chip frequency. In addition, primates with little evidence of mechanically challenging or hard-food diets—such as Cercopithecus spp., Pi. badius, and Pr. verus—evinced higher chipping frequencies than expected. The equivocal and stochastic nature of enamel chipping in the Taï monkeys suggests nondietary factors contribute significantly to chipping. A negative association between canopy preference and chipping suggests a role of exogenous particles in chip formation, whereby taxa foraging closer to the forest floor encounter more errant particulates during feeding than species foraging in higher strata. We conclude that current enamel chipping models may provide insight into the diets of fossil primates, but only in cases of extreme durophagy. Given the role of nondietary factors in chip formation, our ability to reliably reconstruct a range of diets from a gradient of chipping in fossil taxa is likely weak.

Bone Surface Micro-Topography at Craniofacial Entheses: Insights on Osteogenic Adaptation at Muscle Insertions.

Macroscopic details of the bone-muscle interface are represented by a mosaic of calcified features inclusive of fossae, tuberosities, crests, and ridges. These features are in part of an adaptive osteogenic response to dissipate forces of localized mechanical loading. In an osteoarchaeological or paleontological context, these features are interpreted as "musculoskeletal stress markers" to infer habitual behaviors. Microscopic surveys of bone surface topography of the enthesis can reveal localized osteogenic topologies. These features illustrate the developmental mechanisms that produce these bony forms and contribute to an evidential basis to read these structures. Microscopic osteogenic topographies at sites of gnathic muscle attachments located in the craniofacial skeleton were explored in reference to extrapolated loading vectors in an ontogenetic series of craniofacial skeletons of the primate (Procolobus verus). Epoxy resin replicas of bone surfaces were made, and micro-topographical detail viewed with Scanning Electron Microscope. Osteoclastic bone remodeling was found at entheses associated with presumptive net tensile loading. Mineralized fibrocartilage was present at entheses, associated with presumptive net compressive loading. Collectively, these outcomes suggest that entheses develop through adaptive osteogenic activity in response to differential vectors of local mechanical loading. However, the presence of mineralized fibrocartilage also suggests that proliferative cartilage has a role in the development of bone eminences providing functional processes. This study concludes that the vector of muscle loading at entheses as well as proliferative fibrocartilage is influencing the form of bony eminences in the primate craniofacial skeleton defining functional and species defining morphologies. Anat Rec, 302:2140-2155, 2019. © 2019 American Association for Anatomy.

The diversity and conservation of mammals in the Dodo Coastal Forest in southwestern Côte d’Ivoire, western Africa: a preliminary study

To improve the knowledge of non-volant mammal diversity and conservation prospects in the Dodo Coastal Forest (DCF) in southwestern Côte d’Ivoire, we conducted reconnaissance surveys and interviews, and deployed remote cameras. We calculated visual encounter rates (vER) and sign ER (sER) of mammalian taxa and hunting signs, mapped their locations and tested the hypothesis that sightings and signs of primates occurred closer to the river Dodo in and near the gallery forest. We sighted nine taxa, including threatened King Colobus (Endangered, EN), Olive Colobus (Vulnerable, VU), Lowe’s Monkey (VU), the Eastern Lesser Spot-nosed Monkey (VU), and White-bellied Pangolin (VU), with vER of 0.04, 0.12, 0.04, 0.12, 0.04, respectively. We confirmed 14 other taxa with signs including threatened Western Chimpanzee (CR), Pygmy Hippopotamus (Endangered, EN), Bosman’s Potto (VU), and Black-bellied Pangolin (VU), with sER of 0.51, 0.04, 0.08, 0.04, respectively. The most frequently encountered signs were of the Red River Hog at 1.73 signs/km, and the Bushbuck at 0.63 signs/km. Remote cameras captured images of these two taxa at image capture rates (ICR) of 0.044 and 0.022, respectively. Images of the African Buffalo were captured at ICR of 0.044. The 23 confirmed taxa include seven primates, four rodents, three carnivores, six even-toed ungulates, two pangolins and a Tree Hyrax. The mean distance from the river Dodo to the sightings and the signs of the primates was significantly shorter than that of other taxa. This supports our hypothesis. There was a high level of hunting signs (sER = 0.63) indicating that intensive hunting pressure is menacing the fauna. We recommend that authorities take actions against poaching, install a surveillance program, and curtail charcoal-making to ensure the conservation of the threatened mammals of the DCF.

English

We investigated how four primate species in Kakum Conservation Area (KCA) coexisted after logging shrunk their feeding resources. We used multivariate discriminant function analysis to determine whether feeding sites and food types could discriminate them. Results showed that lower canopy discriminated Cercopithecus mona and Cercopithecus petaurista; middle canopy, C. petaurista and Procolobus verus; upper canopy P. verus and Colobus polykomos; seed C. polykomos; fruit, P. verus. Variations in seasonal and zonal selections of feeding sites and food types were significant at the 0.05 level. Primates selected upper canopy, flower and fruit more in rainy season (mean abundance ± se = 14.45±1.2, 10.21±0.53, 17.69±0.7) than in dry season (9.32±0.67, 8.11±0.52, 12.58±0.54); middle canopy and seed more in dry season (13.17±0.12 and 16.7±0.84) than rainy season (8.07±0.53 and 8.43±0.6), respectively. Upper and middle canopies and seed were more selected at the park’s centre (mean abundance ± se = 14.3±1.57, 12.8±1.06 and 16.83±1.16, respectively); and lower canopy, periphery (16.98±1.42). C. polykomos selected the park’s centre mostly (16.6±2.4); C. petaurista, inner (16.9±1.2); and C. mona, periphery (14.7±1.3). Selection by C. polykomos reduced from the park’s centre (mean abundance ± se = 16.6±2.4) through inner (10.5±0.2) to periphery (6.6±1.6); but selection by C. mona reduced from periphery (14.7±1.3) through inner (12.2±1.3) to centre (11.2±1.6). C. petaurista and P. verus appeared to be forest generalists. Seasonal and spatial variations, resource variability and forest conditions facilitated resource partitioning to allow co-existence. Strict measures are required at KCA to facilitate forest regeneration to conserve the primates.   Key words: Conservation, monkeys, resource-shrunk, co-existence, reserve, forest, regeneration.

Diversity and prevalence of gastrointestinal parasites in seven non-human primates of the Taï National Park, Côte d'Ivoire.

Parasites and infectious diseases are well-known threats to primate populations. The main objective of this study was to provide baseline data on fecal parasites in the cercopithecid monkeys inhabiting Côte d’Ivoire’s Taï National Park. Seven of eight cercopithecid species present in the park were sampled: Cercopithecus diana, Cercopithecus campbelli, Cercopithecus petaurista, Procolobus badius, Procolobus verus, Colobus polykomos, and Cercocebus atys. We collected 3142 monkey stool samples between November 2009 and December 2010. Stool samples were processed by direct wet mount examination, formalin-ethyl acetate concentration, and MIF (merthiolate, iodine, formalin) concentration methods. Slides were examined under microscope and parasite identification was based on the morphology of cysts, eggs, and adult worms. A total of 23 species of parasites was recovered including 9 protozoa (Entamoeba coli, Entamoeba histolytica/dispar, Entamoeba hartmanni, Endolimax nana, Iodamoeba butschlii, Chilomastix mesnili, Giardia sp., Balantidium coli, and Blastocystis sp.), 13 nematodes (Oesophagostomum sp., Ancylostoma sp., Anatrichosoma sp., Capillariidae Gen. sp. 1, Capillariidae Gen. sp. 2, Chitwoodspirura sp., Subulura sp., spirurids [cf Protospirura muricola], Ternidens sp., Strongyloides sp., Trichostrongylus sp., and Trichuris sp.), and 1 trematode (Dicrocoelium sp.). Diversity indices and parasite richness were high for all monkey taxa, but C. diana, C. petaurista, C. atys, and C. campbelli exhibited a greater diversity of parasite species and a more equitable distribution. The parasitological data reported are the first available for these cercopithecid species within Taï National Park.

Primer Design for Non-Invasive Genetic Identification of West African Threatened Primates

The Guinean Forests are renowned for their primate diversity, with nearly 30 distinct species. These forests have been identified as some of Africa's most critical primate conservation areas. However, intensive poaching pressure and habitat degradation cause severe threats to these species. The remaining primate populations have low population densities, have secretive habitats, and are wary of humans. This can make field studies and direct observation difficult. To develop a reliable, sensitive and simple molecular identification method using Polymerase Chain Reaction (PCR), we sequenced the mitochondrial D-loop Hypervariable 1 region (HVR1) of Diana monkey ( Cercopithecus diana) and Campbell monkey ( Cercopithecus campbelli). From these sequences and their orthologs within Eastern black-and-white colobus ( Colobus guereza) obtained from GenBank, we designed species-specific primers to amplify fragments of the mitochondrial D-loop HVR1 gene from faecal samples. These primers allow us to differentiate between Diana monkey ( C. diana), Campbell monkey ( C. campbelli), lesser spot-nosed monkey ( Cercopithecus petaurista), Red colobus ( Piliocolobus badius), Olive colobus ( Procolobus verus), King colobus ( C. polykomos), and Geoffroy's black-and-white colobus ( C. vellerosus), demonstrating their potential for the identification of West African threatened primates.

Monkeys in a West African Bushmeat Market: Implications for Cercopithecid Conservation in Eastern Liberia

According to the IUCN [ 1 ], four of the nine anthropoid species found in Liberia are classified as either Vulnerable or Endangered and this number is likely to rise in coming years due to an increase in bushmeat hunting and a growing human population. Bushmeat hunting is the primary cause of primate loss in West Africa and current estimated offtake rates combined with habitat loss have placed four taxa endemic to Upper Guinea forests in danger of extirpation. We surveyed one bushmeat market located on the Liberia – Ivory Coast border to assess the general impact of hunting in one area of Liberia. This market, located near the Ivorian town of Taï, receives meat daily from the Konobo District of eastern Liberia. We visited the market eight times over a four month period in 2009/2010, during which we counted 723 animals including 264 primates. According to our surveys of the market, Cercopithecus petaurista (Lesser spot-nosed monkey) [25% of all primates] was the most abundant primate, followed by Cercopithecus diana (Diana monkey) [19.3%], Cercocebus atys (Sooty mangabey) [12.1%], Colobus polykomos (King colobus) [11.4%], Procolobus verus (Olive colobus) [10.6%], Cercopithecus campbelli (Campbelli monkey) [10.2%], and Procolobus badius (Western red colobus) [9.5%]. We estimate an average of thirty-three primates were exchanged each day we visited and that a minimum of 9,500 primates are traded annually at this locale (6,900 during formal market days and 2,600 on non-market days). Based on an estimated offtake rate of 2.76%, our preliminary analysis suggests that primates in Liberia's Konobo District are likely being hunted at rates approaching unsustainable levels and are in danger of extirpation.

Modularity and integration in ontogeny of the middle facial skeleton in two West African monkey species: collared mangabey (Cercocebus torquatus) and olive colobus (Procolobus verus)

Modularity and integration in ontogeny of the middle facial skeleton in two West African monkey species: collared mangabey (Cercocebus torquatus) and olive colobus (Procolobus verus)

The diurnal primate community of the Tanoé Forest: species composition, relative abundance, distribution, polyspecific associations and conservation status

The Tanoe Forest is located within the original distribution area of the Miss Waldron red colobus ( Piliocolobus badius waldronae ), the diana roloway ( Cercopithecus diana roloway ) and the white napped mangabey ( Cercocebus atys lunulatus ). These three monkey species are classified by IUCN among the 25 most threatened monkeys of the world. Surveys conducted in their believed distribution area in Cote d’Ivoire from 2004 to 2007 highlighted an advanced degradation of habitats, an intensive hunting activity and a subsequent local extinction of some primate species. Field survey conducted in the Tanoe Swamp Forest shown that there is an exception in this dramatic context since this forest still housing threatened species such as the Diana roloway, the white-napped mangabey, and other monkeys of conservation concern: the Geoffroy’s colobus ( Colobus vellerosus ) and the olive colobus ( Procolobus verus ), and probably a viable Miss Waldron monkeys population ( Piliocolobus waldronae ). In addition, this forest hosts the Lowe’s guenon ( Cercopithecus campbelli lowei ) and the lesser spot-nosed guenon ( Cercopithecus petaurista petaurista ), that are widespread in the Tanoe Swamp Forest. Keywords : Tanoe forest, primate community, endangered, Swamp Forest, distribution

Lack of Evidence of Simian Immunodeficiency Virus Infection Among Nonhuman Primates in Taï National Park, Côte d’Ivoire: Limitations of Noninvasive Methods and SIV Diagnostic Tools for Studies of Primate Retroviruses

It is now well established that the human immunodeficiency viruses, HIV-1 and HIV-2, are the results of cross-species transmissions of simian immunodeficiency viruses (SIV) naturally infecting nonhuman primates in sub-Saharan Africa. SIVs are found in many African primates, and humans continue to be exposed to these viruses by hunting and handling primate bushmeat. Sooty mangabeys (Cercocebus atys) and western red colobus (Piliocolobus badius badius) are infected with SIV at a high rate in the Taï Forest, Côte d'Ivoire. We investigated the SIV infection and prevalence in 6 other monkey species living in the Taï Forest using noninvasive methods. We collected 127 fecal samples from 2 colobus species (Colobus polykomos and Procolobus verus) and 4 guenon species (C. diana, C. campbelli, C. petaurista, and C. nictitans). We tested these samples for HIV cross-reactive antibodies and performed reverse transcriptase-polymerase chain reactions (RT-PCR) targeting the gag, pol, and env regions of the SIV genome. We screened 16 human microsatellites for use in individual discrimination and identified 4-6 informative markers per species. Serological analysis of 112 samples yielded negative (n=86) or uninterpretable (n=26) results. PCR analysis on 74 samples confirmed the negative results. These results may reflect either the limited number of individuals sampled or a low prevalence of infection. Further research is needed to improve the sensitivity of noninvasive methods for SIV detection.

The Presence of a vpu Gene and the Lack of Nef-Mediated Downmodulation of T Cell Receptor-CD3 Are Not Always Linked in Primate Lentiviruses

Nef is an accessory protein critical for the ability of human and simian immunodeficiency viruses (HIV and SIV) to replicate efficiently in their respective hosts. Previous analyses of members of 15 different primate lentivirus lineages revealed a link between Nef function and the presence of a vpu gene. In particular, Nef proteins of all vpu-containing viruses had lost their ability to downmodulate the T cell (TCR-CD3) receptor. Here we examined Nef proteins from eight additional SIV lineages, including SIVgor, SIVwrc, SIVolc, SIVgri, SIVdrl, SIVlho, SIVden, and SIVasc, from western lowland gorillas, western red colobus monkeys, olive colobus monkeys, grivet monkeys, drills, L'Hoest's monkeys, Dent's mona monkeys, and red-tailed monkeys, respectively. We found that except for the nef gene of SIVdrl, all of them were efficiently expressed and modulated CD4, major histocompatibility complex class I (MHC-I), CD28, CXCR4, and Ii cell surface expression and/or enhanced viral infectivity and replication. Furthermore, the Nef proteins of SIVgri, SIVlho, SIVwrc, SIVolc, and SIVgor antagonized tetherin. As expected, the Nef protein of SIVgor, which carries vpu, failed to downmodulate CD3, whereas those of SIVwrc, SIVgri, SIVlho, and SIVasc, which lack vpu, were capable of performing this function. Surprisingly, however, the Nef protein of the vpu-containing SIVden strain retained the ability to downmodulate TCR-CD3, whereas that of SIVolc, which does not contain vpu, was unable to perform this function. Although the SIVden Vpu is about 20 amino acids shorter than other Vpu proteins, it degrades CD4 and antagonizes tetherin. Our data show that there are exceptions to the link between the presence of a vpu gene and nef alleles deficient in CD3 modulation, indicating that host properties also affect the selective pressure for Nef-mediated disruption of TCR-CD3 signaling. Our results are also further evidence that tetherin antagonism is a common function of primate lentivirus Nef proteins and that the resistance of human tetherin to Nef represents a relevant barrier to cross-species transmission of SIVs to humans.

Cortical osteogenic activity associated with muscle attachments in the craniofacial skeleton of the primate, Procolobus verus

Cortical osteogenic activity associated with muscle attachments in the craniofacial skeleton of the primate, Procolobus verus

Full-Length Genome Characterization of a Novel Simian Immunodeficiency Virus Lineage (SIVolc) from Olive Colobus ( Procolobus verus ) and New SIVwrc Pbb Strains from Western Red Colobus ( Piliocolobus badius badius ) from the Taï Forest in Ivory Coast

Simian immunodeficiency viruses (SIVs) are found in an extensive number of African primates and humans continue to be exposed to these viruses by hunting and handling of primate bushmeat. Full-length genome sequences were obtained from SIVs derived from two Colobinae species inhabiting the Taï forest, Ivory Coast, each belonging to a different genus: SIVwrc from western red colobus (Piliocolobus badius badius) (SIVwrcPbb-98CI04 and SIVwrcPbb-97CI14) and SIVolc (SIVolc-97CI12) from olive colobus (Procolobus verus). Phylogenetic analysis showed that western red colobus are the natural hosts of SIVwrc, and SIVolc is also a distinct species-specific lineage, although distantly related to the SIVwrc lineage across the entire length of its genome. Overall, both SIVwrc and SIVolc, are also distantly related to the SIVlho/sun lineage across the whole genome. Similar to the group of SIVs (SIVsyk, SIVdeb, SIVden, SIVgsn, SIVmus, and SIVmon) infecting members of the Cercopithecus genus, SIVs derived from western red and olive colobus, L'Hoest and suntailed monkeys, and SIVmnd-1 from mandrills form a second group of viruses that cluster consistently together in phylogenetic trees. Interestingly, the divergent SIVcol lineage, from mantled guerezas (Colobus guereza) in Cameroon, is also closely related to SIVwrc, SIVolc, and the SIVlho/sun lineage in the 5' part of Pol. Overall, these results suggest an ancestral link between these different lentiviruses and highlight once more the complexity of the natural history and evolution of primate lentiviruses.

Tanoé Forest, South-Eastern Côte-d'Ivoire Identified as a High Priority Site for the Conservation of Critically Endangered Primates in West Africa

Human-induced extinction rate of fauna has increased over the last century. The danger is particularly acute in the tropics where conservation resources are scarcest, where habitat conversion is more rapid, and where the threat to biodiversity especially to primate species and populations is greatest. This is the case for the whole primate community occurring at the eastern part of the Upper Guinea forests. The situation is particularly critical for Côte d'Ivoire. To update the distribution and conservation status of primates in south-eastern and south-central Côte d'Ivoire, we conducted surveys consisting of interviews and walks in selected forests reserves, National Parks, private forests, and unprotected forests in Côte d'Ivoire in 2004-2006. Among the forests surveyed, the Tanoé forest is the only forest where several endangered primate taxa have survived. The diana roloway ( Cercopithecus diana roloway) was found and the Miss Waldron's red colobus ( Piliocolobus badius waldronae) was suspected in this forest. These monkeys are listed among the 25 most threatened primates in the world and the probable extinction of the latter was reported in the literature. The Tanoé forest also supports two Endangered monkey species ( Cercocebus atys lunulatus and Colobus vellerosus) and one Near Threatened monkey species ( Procolobus verus). This forest represents the most “threatened hotspot” for primate diversity and a priority for primate conservation in West Africa. Throughout Tanoé forest, Primate Conservation Societies have a unique opportunity to prevent the extinction of West African primates that are under severe threats.

Phylogenetic diversity and the conservation biogeography of African primates

AbstractAim Phylogenetics has an important role in conservation biogeography. However, there are few data on the phylogenetic diversity of African primates. The phylogenetic diversity (PD) of a species is a measure of its taxonomic distinctness and can be estimated by looking at the phylogenetic relationships among taxa. Species‐specific metrics on PD can then be used to determine conservation priorities at various biogeographical scales. We used PD metrics to rank 55 African primate species according to their conservation priorities at the country level and within six African biogeographical regions. We also addressed the following question: are there differences in conservation rankings between the IUCN Red List and our PD metrics?Location Africa.Methods We created a consensus phylogeny for all African primate clades based on genetic studies. Analyses of species distributions were determined using presence/absence scores at two levels: country and biogeographical region. A node‐based method that standardizes for widespread taxa and endemicity was used to calculate PD indices. Hierarchical cluster analysis was used to convert one of the standardized, phylogenetic indices into three clusters that could be ranked and compared with the main IUCN conservation rankings of endangered, vulnerable, and lower risk.Results At the country and region levels, the top‐priority species in terms of PD are Pan paniscus, Macaca sylvanus, Arctocebus calabarensis, Gorilla beringei, Arctocebus aureus, Allenopithecus nigroviridis, Gorilla gorilla, Procolobus verus, Cercopithecus solatus, Cercocebus galeritus, Colobus angolensis, Theropithecus gelada, Galagoides zanzibaricus, Galagoides granti, and Procolobus (Piliocolobus) badius. Geographic rankings were highest for the Democratic Republic of the Congo (country level) and Central Africa (region level). Although there were no overall differences between IUCN conservation ranks and the PD rankings, there were significant differences between the two systems for vulnerable and endangered primate taxa.Main conclusions There are few ecological and behavioural data on populations of some of the African primates that represent the highest levels of phylogenetic diversity. Studies of primate taxa with high PD rankings should focus on identifying sites suitable for intensive studies of population densities, feeding ecology, and reproductive behaviour. We suggest that PD metrics can serve as an important, complementary data set in the IUCN ranking system for primates.

Dispersal patterns among olive colobus in Taï National Park

In Primates, females are more likely to be philopatric than males. However, in some species like Procolobus verus, females or individuals of both sexes disperse. In Tai National Park, Ivory Coast, olive colobus groups are small, with one or two adult males and ≤6 females. Dispersal is common for juveniles and adults of both sexes. Adult male dispersal is less common than adult female dispersal. Adult females immigrated especially into small, one-male groups indicating that food competition played a role. Furthermore, unknown sexually receptive females visited resident groups and mated with the resident males for a few days before disappearing again. Adult males dispersed when this improved their mating opportunities. All juveniles left their natal groups. The dispersal of juveniles may be a strategy to prevent inbreeding with their parents. Dispersal by juvenile males furthermore seemed to be the result of mate competition. The high dispersal rates, visits by receptive females, and dispersal of all individuals in the population suggest that moving between groups is a strategy that can be used ad hoc in several situations more easily in the olive colobus than in most other primates. The predation risks related to moving between groups were reduced by dispersing in conspecific or allospecific groups and by dispersing to neighboring groups.

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.

Dyadic associations of red Colobus and diana monkey groups in the Taï National Park, Ivory Coast

Members of the genus Colobus have been observed to associate frequently with Cercopithecus monkeys in several African sites. In the Tai National Park, Ivory Coast, one group of western red colobus was found to be in association with one particular group of diana monkeys more than could be expected by chance (Holenweg et al., 1996). We show that dyadic association is not an idiosyncrasy of these two groups, but rather a pattern that is general for our study site. All five red colobus groups we studied were closely associated with diana monkeys during more than 60% of the time. Four groups had one particular diana partner group, the fifth two different partners. Apart from the red colobus, three more primate species, the olive colobus, Campbell's monkey, and the lesser spot-nosed monkey, were also strongly attracted to diana monkeys.

Dental sexual dimorphism and morphology in african colobus monkeys as related to diet

We considered the relationship between dental sexual dimorphism and diet in 542 specimens of olive, red, and black-and-white colobus. Using univariate statistical techniques, we examined 41 measurements of the maxillary and mandibular dentitions. The results reveal two trends of dental sexual dimorphism in black-and-white colobus wherein (i) maleColobus guereza andC. angolensis are generally larger than females throughout the dentition and (ii)C. satanas and, to a lesser degree,C. polykomos exhibit reduced sexual differences in the canine base and females are slightly larger than males in noncanine dimensions. Females of the red colobus,Procolobus (Piliocolobus) badius, are slightly larger than males in most noncanine measurements but canine sex differences are more pronounced than those of black-and-white colobus.Procolobus (Procolobus) verus, the olive colobus, is characterized by some of the largest canine sex differences, yet the sexes do not differ much in noncanine mean values. When patterns of sexual dimorphism are considered in terms of specific ecology and behavior, it is possible to relate sex differences, in part, to known dietary differences. For example, overall dental morphology and the trend of sexual differences inC. satanas andC. polykomos seem to be associated with the consumption of a diet rich in seeds. The pattern of dental sexual dimorphism inC. badius may also be influenced by dietary factors in that their patrilineal social organization could restrict female access to certain foods thereby affecting rates of attrition and creating selection pressure for larger teeth. Relatively less is known of the ecology and social organization ofP. verus but their dental sexual dimorphism is possibly less related to dietary factors than is the case for red or black-and-white colobus.