A computer ethological-pharmacological analysis of the intraspecific behavior of primates

Experiments were performed on primates (Cercopithecus sabeus, Macaca maurus, Cebus apella). Possibility to formalize the structure of normal and pathological monkey behaviour was shown by computerized technique. Rigid dominant-subordinate structures (linear type) were demonstrated on Macaca maurus, Cercopithecus sabeus, Cebus apella. These structures display some variants of normal relationship between monkeys. Raising in isolation from conspecifics determines behavioural disadaptation and pathological behaviour, e.g. "timid-defensive" syndrome. Model of "timid-defensive" syndrome in isolated primates seems to be useful for psycho-pharmacological research, for assessment of anxiolytic and antidepressive properties of drugs.     

The diet and feeding behaviour of Cercopithecus aethiops tantalus.

The feeding behaviour of representative groups of tantalus monkeys (Cercopithecus aethiops tantalus) was observed during 1974-1975 in three habitats in Cameroon. Observations took place during the wet and dry seasons in sahelian savannah, guinea savannah and farmed forest. The tantalus monkeys were similar to other races of C.aethiops that have been studied in that they were omnivorous and lacked any narrow specialisations of either diet or feeding techniques. The dietary range was similar in all three habitats, although considerable seasonal variation occurred. About one third of all feeding took place on the ground.     

Diet and feeding behaviour of samango monkeys (Cercopithecus mitis labiatus) in Ngoye Forest, South Africa

The samango monkey occurs at the southern limit of the range of Cercopithecus mitis. Greater climatic seasonality at this latitude results in more predictable fruiting patterns. In addition, there are no diurnal sympatric primate frugivores. Under these conditions, the diet and feeding strategies of samango monkeys would be expected to differ notably from those of central or east African C. mitis subspecies. Contrary to these expectations, the preliminary observations reported here indicate that diets of samango and blue monkeys differ only superficially in the proportions of items eaten. Similarities in feeding behaviour are especially marked during the dry season period when fruit is not abundant. Both samango and blue monkeys tend to be less selective in their choice of food species and to eat available food species regardless of their energy content; a shift toward less nutritious items such as leaves is also noted. Feeding behaviour during the summer wet season is characterized by the selection of fruits with high-energy values. A high proportion of visits by the monkeys to areas of greater food availability suggests a concentration of feeding effort in food patches and the selection of higher energy food species within patches.     

New simian immunodeficiency virus infecting De Brazza's monkeys (Cercopithecus neglectus): evidence for a cercopithecus monkey virus clade

Nearly complete sequences of simian immunodeficiency viruses (SIVs) infecting 18 different nonhuman primate species in sub-Saharan Africa have now been reported; yet, our understanding of the origins, evolutionary history, and geographic distribution of these viruses still remains fragmentary. Here, we report the molecular characterization of a lentivirus (SIVdeb) naturally infecting De Brazza's monkeys (Cercopithecus neglectus). Complete SIVdeb genomes (9,158 and 9227 bp in length) were amplified from uncultured blood mononuclear cell DNA of two wild-caught De Brazza's monkeys from Cameroon. In addition, partial pol sequences (650 bp) were amplified from four offspring of De Brazza's monkeys originally caught in the wild in Uganda. Full-length (9068 bp) and partial pol (650 bp) SIVsyk sequences were also amplified from Sykes's monkeys (Cercopithecus albogularis) from Kenya. Analysis of these sequences identified a new SIV clade (SIVdeb), which differed from previously characterized SIVs at 40 to 50% of sites in Pol protein sequences. The viruses most closely related to SIVdeb were SIVsyk and members of the SIVgsn/SIVmus/SIVmon group of viruses infecting greater spot-nosed monkeys (Cercopithecus nictitans), mustached monkeys (Cercopithecus cephus), and mona monkeys (Cercopithecus mona), respectively. In phylogenetic trees of concatenated protein sequences, SIVdeb, SIVsyk, and SIVgsn/SIVmus/SIVmon clustered together, and this relationship was highly significant in all major coding regions. Members of this virus group also shared the same number of cysteine residues in their extracellular envelope glycoprotein and a high-affinity AIP1 binding site (YPD/SL) in their p6 Gag protein, as well as a unique transactivation response element in their viral long terminal repeat; however, SIVdeb and SIVsyk, unlike SIVgsn, SIVmon, and SIVmus, did not encode a vpu gene. These data indicate that De Brazza's monkeys are naturally infected with SIVdeb, that this infection is prevalent in different areas of the species' habitat, and that geographically diverse SIVdeb strains cluster in a single virus group. The consistent clustering of SIVdeb with SIVsyk and the SIVmon/SIVmus/SIVgsn group also suggests that these viruses have evolved from a common ancestor that likely infected a Cercopithecus host in the distant past. The vpu gene appears to have been acquired by a subset of these Cercopithecus viruses after the divergence of SIVdeb and SIVsyk.     

Interspecies semantic communication in two forest primates

West African Diana monkeys (Cercopithecus diana) and Campbell's monkeys (Cercopithecus campbelli) frequently form mixed-species associations. Males of both species produce acoustically distinct alarm calls to crowned eagles (Stephanoaetus coronalus) and leopards (Panthera pardus), two of their main predators. Field playback experiments were conducted to investigate whether Diana monkeys respond to Campbell's alarm calls and whether they understand the calls' semantic content. Diana monkeys responded to playback of Campbell's leopard or eagle alarm calls as though the original predator were present. In a second experiment, Diana monkeys were primed with either Campbell's eagle or leopard alarm calls and then subsequently probed with the vocalizations of a crowned eagle or a leopard. Results showed that monkeys used the semantic information conveyed by the Campbell's alarm calls to predict the presence of a predator. The data are consistent with the hypothesis that non-human primates are able to use acoustic signals of diverse origin as labels for underlying mental representations.     

Effects of habitat disturbance and food supply on population densities of three primate species in the Kakamega Forest, Kenya

While habitat disturbance and food availability are major factors thought to determine the abundance of primates, evidence for their importance is uneven. We assessed the effects of these factors on three monkey species, guerezas ( Colobus guereza ) , blue monkeys ( Cercopithecus mitis ) and redtails ( Cercopithecus ascanius ), in four areas of the Kakamega Forest, Kenya. Group densities of guerezas and blue monkeys were higher in areas where disturbance levels were also higher. Food availability measured as basal area density of food trees did not correlate significantly with the group densities of any of the three monkeys. The diversity of food trees, another potential measure of food abundance did, however, correlate with group densities of guerezas and blue monkeys suggesting that food availability may positively influence monkey density, and may sometimes increase with disturbance. Group densities of redtails did not correlate with any habitat variable examined, suggesting that factors other than those we considered may have influenced the abundance of this species particularly.     

Identification of a new simian immunodeficiency virus lineage with a vpu gene present among different cercopithecus monkeys (C. mona, C. cephus, and C. nictitans) from Cameroon

During a large serosurvey of wild-caught primates from Cameroon, we found 2 mona monkeys (Cercopithecus mona) out of 8 and 47 mustached monkeys (Cercopithecus cephus) out of 302 with human immunodeficiency virus (HIV)-simian immunodeficiency virus (SIV) cross-reactive antibodies. In this report, we describe the full-length genome sequences of two novel SIVs, designated SIVmon-99CMCML1 and SIVmus-01CM1085, isolated from one mona (CML1) and one mustached (1085) monkey, respectively. Interestingly, these viruses displayed the same genetic organization (i.e., presence of a vpu homologue) as members of the SIVcpz-HIV type 1 lineage and SIVgsn isolated from greater spot-nosed monkeys (Cercopithecus nictitans). Phylogenetic analyses of SIVmon and SIVmus revealed that these viruses were genetically distinct from other known primate lentiviruses but were more closely related to SIVgsn all across their genomes, thus forming a monophyletic lineage within the primate lentivirus family, which we designated the SIVgsn lineage. Interestingly, mona, mustached, and greater spot-nosed monkeys are phylogenetically related species belonging to three different groups of the genus Cercopithecus, the C. mona, C. cephus, and Cercopithecus mitis groups, respectively. The presence of new viruses closely related to SIVgsn in two other species reinforces the hypothesis that a recombination event between ancestral SIVs from the family Cercopithecinae is the origin of the present SIVcpz that is widespread among the chimpanzee population.     

Red colobus as prey: the leaping habits of five sympatric Old World monkeys

This study explored the leaping habits of five sympatric Old World monkeys (Colobus badius, Colobus guereza, Cercopithecus ascanius, Cercopithecus mitis and Cercocebus albigena) in an attempt to determine why chimpanzees prefer to hunt red colobus. We videotaped the leaps of the monkeys for 3 months in Uganda's Kibale National Park. Data were collected on leap preparation time as well as several other variables of the leaps. The leap preparation time of red colobus was found to be about double that of the other species studied. This difference is a likely reason why red colobus represent the preferred prey of chimpanzees. The hypothesis that red colobus spend more time in isolated trees than do other species was not supported.     

Gastrointestinal parasites of the guenons of western Uganda

From January 1998 to December 2002, we collected 293 fecal samples from free-ranging individuals of the 4 guenon species of western Uganda, i.e., redtail guenons (Cercopithecus ascanius), blue monkeys (Cercopithecus mitis), l'hoesti monkeys (Cercopithecus lhoesti), and vervet monkeys (Cercopithecus aethiops), to quantify the prevalence of gastrointestinal parasites. Helminth eggs, larvae, and protozoan cysts were isolated by sodium nitrate flotation and fecal sedimentation. Helminth parasites were identified, and infection prevalence was determined for all 4 guenon species. Coprocultures facilitated identification of strongylate nematodes. For the most common species, the redtail guenon, we documented prevalence of protozoan parasites and examined the effect of season and host sex on infection prevalence. Six nematodes (Strongyloidesfulleborni, Oesophagostomum sp., unidentified strongyle, Trichuris sp., Streptopharagus sp., and Enterobius sp.), 1 cestode (Bertiella sp.), 1 trematode (Dicrocoeliidae), and 5 protozoans (Entamoeba coli, Entamoeba histolytica, lodameoba butschlii, Giardia lamblia, and Chilomastix mesnili) were detected. Seasonal patterns of infection were not readily apparent for any parasite species infecting redtail guenons. Although prevalence never differed between male and female guenons, only adult females were infected with Oesophagostomum sp. and S. fulleborni.     

Cooperation and competition in two forest monkeys

Putty-nosed monkeys, Cercopithecus nictitans stampflii, occurat various sites in West Africa, particularly in the transitionzone between rainforest and savannah. The species is sometimesseen in primary rainforest, although at a curiously low densitycompared with that of other monkey species. We conducted a 24-monthfield study in the tropical rainforest of Taï NationalPark, Ivory Coast, and found that putty-nosed monkeys requirean ecological niche almost identical to that of the Diana monkeys,Cercopithecus diana diana. Moreover, the niche breadth of putty-nosedmonkeys was significantly decreased in the presence of Dianamonkeys, suggesting that feeding competition with Diana monkeyskept putty-nosed monkeys from successfully colonizing a rainforesthabitat. However, contrary to the interspecies competition hypothesis,groups of both species almost completely overlapped in homeranges and formed near-permanent mixed-species associations,rather than avoiding each other. We hypothesized that Dianamonkeys tolerated immigrating putty-nosed monkeys and formedmixed-species groups with them, despite high levels of competition,because of their merit in predation defense. Direct observationsand a series of field experiments confirmed that male putty-nosedmonkeys play a vital role in defense against crowned eagles,suggesting that putty-nosed monkeys obtain access to feedingtrees by offering antipredation benefits to Diana monkeys. Wediscuss these findings in light of biological market theory.     

Simian immunodeficiency viruses from central and western Africa: evidence for a new species-specific lentivirus in tantalus monkeys.

Although up to 50% of African green monkeys (AGMs) are infected by simian immunodeficiency viruses (SIV) in their natural habitat, they remain asymptomatic carriers of these lentiviruses. They provide an attractive model to study not only the origin but also the link among genetic variation, host-virus adaptation, and pathogenicity of primate lentiviruses. SIVagm have been isolated from three species of AGM: the vervet (Cercopithecus pygerythrus), the grivet (Cercopithecus aethiops), and the sabaeus (Cercopithecus sabaeus) monkey. We studied four new SIVagm isolates from a fourth AGM species, the tantalus monkey (Cercopithecus tantalus), caught in the Central African Republic, and four new isolates from feral sabaeus monkeys from Senegal. Antigenic properties and partial env sequences were used to evaluate the diversity among these isolates. Alignment of env sequences in SIVagm isolated from tantalus and sabaeus monkeys permitted detailed mapping of the variable and conserved domains in the external glycoprotein. Genetic distances indicated that SIVagm isolates from tantalus monkeys are the most divergent among SIVagm in feral AGMs in Africa. The fact that AGMs are infected by four distinct lentiviruses, each specific for a single AGM species, supports the hypothesis of a coevolution of these viruses and their natural hosts and suggests that SIV transmission is a rare event among separated AGM species in the wild.     

Early infant development and maternal care in free-ranging vervet monkeys

The interactions of infant vervet monkeys (Cercopithecus aethiops) with their mothers were examined during the first 12 weeks of life. During this period there was a gradual rise in behaviour associated with increasing independence from the mother: female infants were slightly advanced over males on measures of decreasing contact with mothers and increasing rejections from the nipple. There were differences between the mothers in the ways they interacted with their infants such that no consistent maternal styles could be defined. Dominance rank of the mother did however influence her behaviour towards her infant, and high ranking mothers tended to be less rejecting towards sons, but more rejecting towards daughters, than were low ranking mothers. It is suggested that since vervet mothers have access to allomothers they may not be limited to dichotomous mothering styles.     

Diet of samango monkeys (Cercopithecus mitis erythrarchus) in the Cape Vidal dune forest, South Africa

The samango monkey ( Cercopithecus mitis erythrarchus Peters, 1852) is the southernmost representative of the widely-distributed polytypic Cercopithecus mitis species-group. At Cape Vidal (28 S) climatic seasonality causes significant seasonal fluctutation in food abundance. There are, however, no congeneric competitors, and few arboreal frugivores (birds, bats). In spite of seasonality of food abundance at Cape Vidal, samango monkeys maintain a high quality diet, dominated by fruit (51.7%), throughout the year. To a large extent this is made possible by their broad dietary tolerances and the effect of competitive release on food choice. Seasonal insect abundance does, however, place serious constraints on the availability of readily-digestible protein and the acquisition of protein-rich foods must be seen as the critically limiting factor in the dietary behaviour of the samango monkey. Adaptation of gut morphology and symbiotic microflora permit samangos to supplement the diet with large amounts of protein-rich foliar and floral items. Where necessary, even large quantities of less palatable items, such as unripe fruits and mature leaves, may be ingested. Although insects form a small part of the diet a larger variety, than used by equatorial C. mitis populations, are included in the diet. Given that there are no congeneric competitors, nor are the monkeys particularly food stressed, I suggest that the diet of the samango monkey at Cape Vidal most closely reflects the intrinsic food choices of the C. mitis species-group.     

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.     

The influence of habitat on behaviour in a group of St. Kitts green monkeys

The relationships between specific ecological variables and the expression of behaviours were investigated in a group of green monkeys ( Cercopithecus aethiops ) inhabiting an ecologically diverse home range on the dry savanna-like peninsula of St. Kitts, West Indies. The group's behaviour was shown to vary between areas that differed with respect to four factors produced from a factor analysis of 20 ecological variables.
A number of relationships between behaviour and ecology were found that have not been previously described. Social behaviours were negatively related to cover, while attention behaviours were positively related to cover. Agonistic behaviours and affiliative behaviours were positively related to food abundance. Open areas with edge proved to be important to the group, and a number of behaviours were expressed for longer durations and/or more frequently in these areas. Comparisons of this study with others illustrates a need to examine carefully behavioural ecological relationships using quantitative methodology.     

Referential labelling in Diana monkeys

Animal semantic communication has received considerable theoretical and empirical attention because of its relevance to human language. Advances have been made by studies of alarm-call behaviour in nonhumans. In monkeys, for example, there is evidence that recipients have a fairly sophisticated understanding of a call's meaning; that is, the predator type usually associated with a certain alarm call. Little is known, however, about the mental mechanisms that drive call production in nonhuman primates. In some nonprimate species, it has been found that signallers do not respond to a predator's physical features but instead seem to respond to its relative threat or direction of attack. In these species, therefore, alarm calls do not denote different predator categories but simply reflect different types or levels of danger. Because different predator categories typically impose different types and degrees of threat it is entirely possible that nonhuman primates also respond to threat rather than a predator's category. This study examined how wild Diana monkeys, Cercopithecus diana, of the Ta? forest, Ivory Coast, label predation events. By altering playback stimuli and the position of a concealed speaker, I investigated whether Diana monkeys respond with acoustically different alarm calls depending on a predator's (1) distance (close versus far), (2) elevation (above versus below), or (3) category (eagle versus leopard). Analysis of male and female alarm-call behaviour showed that Diana monkeys consistently responded to predator category regardless of immediate threat or direction of attack. Data further suggested that, in addition to predator category, monkeys' alarm calls might also convey information about the predator's distance. Copyright 2000 The Association for the Study of Animal Behaviour.     

Within-group differences in captive Diana monkey (Cercopithecus diana diana) behaviour

This case study examines the activity budgets of captive Diana monkeys (Cercopithecus diana diana) and discusses results in the context of what is known regarding captive and wild-type behaviour in this species and other guenons. The activities of a family group of Diana monkeys (two parents and four offspring) housed at Edinburgh Zoo, UK, were quantified using a 5-min interval scan sampling technique. The 5100 observation points collected showed that the subjects spent the largest proportion of their time observing (approx. 46%), followed by feeding (approx. 15%), playing (approx. 11%), mutual grooming (approx. 8%) and resting (approx. 7%). The daily activity budgets for each of the subjects were tallied and, at the end of the 10-day observation period, used to produce a data matrix consisting of nine behaviour variables per subject. Clear among-individual differences in activity were identified with canonical discriminant function analysis. This multivariate approach illustrated how the combined behaviours of the parent male were distinct from those of the rest of the family group. Within the remainder of the group, the three youngest offspring displayed similar activity budgets, whereas the overall behaviour of the eldest offspring (a female) was between that of its siblings and her mother.     

Causal knowledge of predators' behaviour in wild Diana monkeys

Wild Diana monkeys, Cercopithecus diana, of Ta? forest, Ivory Coast, are preyed upon by leopards, Panthera pardus, and chimpanzees, Pan troglodytes. These two predators differ in their main hunting tactic and Diana monkeys attempt to avoid predation with two distinct antipredator strategies: conspicuous alarm-calling behaviour to leopards and silent, cryptic behaviour to chimpanzees. However, the Diana monkeys' choice of the appropriate antipredator strategy is complicated by the fact that chimpanzees themselves also fall prey to leopards. Chimpanzees give loud and conspicuous alarm screams when they detect a leopard. When these chimpanzees' leopard alarm calls were played back to different groups of Diana monkeys, in about half of the cases recipients switched from a chimp-specific cryptic response to a leopard-specific conspicuous response, suggesting that some individuals assumed the presence of a leopard. Groups whose home range was in the core area of the resident chimpanzee community were more likely to respond this way than more peripheral groups, indicating between-group differences in semantic knowledge. In a follow-up experiment, the monkeys' understanding of the chimpanzee alarm calls was further assessed with a prime-probe technique. Monkeys were primed with chimpanzee alarm calls and then, 5 min later, tested with leopard growls to see whether they were able to anticipate the presence of a leopard. Results were consistent with the hypothesis that monkeys responding cryptically to chimpanzee alarm calls did so because they were not able to understand the calls' meaning. Data are discussed with respect to three possible cognitive mechanisms, associative learning, specialized learning programmes, and causal reasoning, that could have led to causal knowledge in some individuals but not others. Copyright 2000 The Association for the Study of Animal Behaviour.     

Torsion of the colon in vervet monkeys: association with an atherogenic Western-type of diet.

The risk of torsion of the colon in adult male vervet monkeys (Cercopithecus aethipos) increased when they were fed with an atherogenic Western-type of diet. No cases occurred in females and rapid diagnosis is necessary to prevent lethal consequences.