The dynamics of species composition in polyspecific association of C. diana and other Cercopithecus monkeys in the Tai National Park, Ivory Coast
Kyoto University, Japan
Polyspecific association is usually formed by phylogenetically closely related species, which occupies similar ecological niche. The reason for interspecific coexistence has been considered to be an adaptive significance that exceeds cost of potential competition. Studies on primate polyspecific association have focused on the significance by comparing two states of species composition, a focal species associated with a partner species or not. Nevertheless, more than two species of Cercopithecus usually occur sympatrically in tropical Africa and they often form polyspecific association with each other and with species form different genus. In polyspecific association of more than two species, behavior of a focal species may be affected by association states of more than one partner species. In Tai National Park, Ivory Coast, three species of Cercopithecus monkeys formed polyspecific association with four species from different genera. Association rates for Cercopithecus monkeys were so high that they were hardly found in single species groups. Species composition of association changed very often, but the composition of two Cercopithecus and two Procolobus species occurred most often and had longest duration. The dynamics of species composition in Cercopithecus polyspecific association was influenced by Colobinae species.
Chimpanzees and domestic dogs can take the visual perspective of others
Max-Planck Institute for Evolutionary Anthropology, Germany
Knowing what others can see is an adaptive skill for social living animals. In the study of Hare et al (2000) two chimpanzees were put into a competition over two pieces of food. One was visible for both of them and one was hidden behind a barrier for the dominant chimpanzee but visible for the subordinate. Getting a small headstart the subordinates preferred to approach that piece that the dominant could not see. They concluded that chimpanzees can take the visual perspective of others. Karin-D'Arcy and Povinelli (2002) reported that they could not replicate these findings but they used different distances between the competitors and between the places with the food to those used in the original study. Here we present a replication of the Hare et al study. Our results show that the distances and therefore the level of competition have a big influence on the performance of the apes.
In a similar but cooperative setting we investigated the ability of domestic dogs to take the visual perspective of humans. Two objects were placed between a human and a dog. One was visible for both - the human and the dog, and the other one was only visible for the dog. The human told the dog to "Fetch!" without designating either object in any way. Dogs went preferentially to the object the human could see, even though they themselves could see both objects equally, whereas when the human could see both objects they had no preference. So the dogs seem to determine a person's viewing angle to decide which object she was referring to with a "Fetch!" command.
It can be concluded that - although having a completely different evolutionary history, both dogs and chimpanzees can take the visual perspective of others in certain situations.
Theory of Mind in Chimpanzees: Insights from Comparative Research
Department of Psychology, University of Michigan, U.S.A.
Since Premack and Woodruff coined the term "theory of mind" in 1978, Research investigating how children understand the unobservable causes behind others' behaviors has yielded rich insight into the development of early social cognition. Recent research has highlighted several key components of children's theory of mind development, and compelling evidence for a universal human developmental trajectory, across linguistic and geographical barriers, has emerged. Researchers investigating these abilities in non-human primates, however, have historically been scarce, and not nearly so homogenous in their findings and interpretations. This talk will review recent findings relevant to the theory of mind capabilites of human children and non-human primates, address the methodological difficulties involved in testing chimpanzees, and discuss the ways in which research with non-human subjects has impacted our conception of human theory of mind development.
Activity, Diet, Fecal Steroids and Reproductive Parameters in Female Chimpanzees: Comparisons between Mahale (Tanzania) and Bossou (Guinea)
Division of Veterinary Medicine, Faculty of Agriculture, Gifu University, Japan
Department of Cellular and Molecular Biology, PRI, Kyoto University, Japan
Long-term researches on wild chimpanzee populations in different study sites have revealed that wide variability of females°« reproductive parameters. Although it has been argued that female reproductive potential is influenced by ecological and social factors, there is no empirical observation by which factor and to what extent female reproductive potential is constrained. In order to illuminate the response of reproductive potential to different habitat conditions, we compared the activity, diet, ovarian hormonal levels and reproductive parameters in female chimpanzees of two wild populations, Mahale (Tanzania) and Bossou (Guinea). We collected behavioral data and fecal samples from the cycling females between July and October 2001 at Mahale and between December 2001 and March 2002 at Bossou. A comparison of activity budget showed that Mahale females prolonged foraging time and cut off resting time. This suggests that foraging efficiency of females was lower at Mahale than at Bossou. The composition of diet and traveling speed were different between females at both study sites, which might be related to the difference in their foraging efficiency. A comparison of ovarian hormone levels showed that the average levels of estradiol-17? and estrone conjugates during the follicular phase and the average levels of progesterone and pregnanediol-3-glucronide during the luteal phase were significantly higher in Bossou females than in Mahale females. This suggests that ovarian function in Mahale females were affected by nutritional stress. In addition, females°« reproductive parameters showed that Mahale females reached sexual maturity later, recovered postpartum sexual swelling later and bred more slowly than Bossou females did. The results of the present study indicate that the habitat conditions which are related to feeding of females influence ovarian functions through their nutritional status, and lead to the difference in females°« reproductive potentials in wild chimpanzee populations.
Low genetic variation and biased distribution of mtDNA haplotypes of Japanese Macaque (Macaca fuscata) on Yakushima Island
Kyoto University, Japan
We found 6 haplotypes at 203bp of mtDNA control region among 280 specimens from fecal DNA of Japanese Macaques in Yakushima Island population. The small diversity of the nucleotide (¶– = 0.0021) and the haplotype frequency that was so biased to one (82.9%) of the 6 haplotypes seemed to be influenced by the huge explosion of Kikai Caldera (7300 y BP) located near this Island and which was one of the largest eruptions during the later Quaternary. And also the geographical distribution of 6 haplotypes was not even horizontally in this island. One haplotype of the highest frequency was distributed widely, whereas the other 5 haplotypes were found only at the lowland. Some paleobotanical studies reported that the grass field was generally distributed after this eruption and the forest was supposed to have recovered earlier in the lowland than the higher area. This different process of recovery would have had influences on the recovery of Japanese macaque population.
A Competition Model within and across Groups Explaining the Contrast between the Societies of Chimpanzees and Bonobos
Kyoto University, Japan
Two apes species, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), show a peculiar contrast in their social structure. The contrast cannot be explained only by differences in their ecological conditions as has been suggested. This study presents a mathematical model to interpret the contrast, through a competition game within and across groups. Two alternative strategies, Dispersal and Association, are applied to the model, in order to represent Within- Group-Competition (WGC). Two alternative strategies, Hawk and Dove, are also applied to the model, in order to represent Between-Group-Competition (BGC). Mathematical analysis is executed for the frequencies of three mixed-strategists: Dispersal-Hawk, Dispersal-Dove and Association. The population dominated by Dispersal-Hawk and Dispersal-Dove strategists, or by Association strategists, is assumed to characterize the social structure of chimpanzees or bonobos, respectively. The model predicts that each social structure can be evolutionary stable under the same ecological condition, and will not easily recover once its replaced by the other. This stability is through a bi-directional influence: the influence of BGC on WGC and vice versa. The model suggests that the possibility of fatal violence within a group strengthens the robustness of each social structure.
What Can We Learn from Group Hunting Behavior of Chimpanzees?
Faculty of Child Studies, Kamakura Women°«s University, Japan
Since the end of the °∆80s, field primatologists have accumulated a lot of information about group hunting behavior of wild chimpanzees, which activates comparisons among various populations across the species°« habitats (in particular, Gombe, Mahale, Taï, and Ngogo). Such comparisons have highlighted several interesting issues, e.g. cooperative hunting and social factors affecting hunting decisions, while some important aspects seem to have been neglected. The purpose of this paper is to review the recent publications about chimpanzee group hunting and to pose two more questions based on the findings from Mahale. One is whether chimpanzees exhibit distinct patterns of group hunting according to prey species (especially among arboreal monkeys), which is essential to understand why chimpanzees tend to hunt specific prey (e.g. red colobus) in groups. The other is how and why females and immatures participate in group hunts, which should not be ignored considering the fact that, at least in Mahale and Gombe, not only adult males but also adult females and adolescent males capture red colobus to some degree.
Relationships among the Proportion of Fruits Consumed, Daily Travel Distances and Party Sizes of Pan paniscus
Sugiyama Jogakuen University, Japan
Great Ape Research Institute, Hayashibara, Japan
Daily distances traveled by wild Pan paniscus at Wamba, Democratic Republic of Congo, is reported in relation to their feeding behavior and party sizes. The E1 and E2 groups, two of the six groups of Pan paniscus inhabiting the Wamba region, were observed during the 1984 and 1988 study periods. Data analyzed in the present study were collected while following Pan paniscus parties in the forest with minimal provisioning. During the study periods, fruits, especially those of Landolphia and Dialium species, were overall a main food item, representing more than 60% of the Pan paniscus diet. Relationships between the proportion of fruits consumed and daily distance traveled was observed; i.e., when a large proportion of fruits was consumed relative to other food items, the daily distances traveled became shorter. Also, relationships between the party sizes of Pan paniscus and daily distances traveled by them will be analyzed and discussed in relation to the proportion of fruits consumed by them.
Which Males Sire Many Infants in a Provisioned Group of Japanese Macaques?
Kyoto University, Japan
Genetic studies have shown male dominance rank and reproductive success are positively related in many primate species. But some studies showed it is not true in Japanese macaques. I analyzed behavioral data and genetic data, and disclosed the characters of males who sired many infants and the influence of female mate choice on male mating success. In the study group, Arashiyama E troop in Kyoto, Japan, their personal profiles such as tenure were known. There were about 100 females in this group, but only 10 babies were born in 2002 and 13 in 2003 because of birth controls on many females. I determined the paternity of all 23 babies born last two years. Males in this group were composed of high ranking males, peripheral males and young males. High ranking males were in the central part of the group, but sired only 2 infants. Peripheral males were less familiar to females, but sired 14 infants. Non troop males sired 6 infants. Male°«s tenure and the number of offspring were negatively related. Female who gave birth mated frequently with high ranking males out of their conception periods and not so frequently in such periods. The number of their mating with peripheral males increased during their conception periods. In conclusion, female mate choice in their conception periods influenced male reproductive success and so high ranking males whose tenure were long did not sire infants.
Plant Phenology and Foraging Behavior of Chimpanzees (Pan Troglodytes Schweinfurthii) in the Mahale Mountains National Park, Tanzania
Kyoto University, Japan
The fruiting, flowering and flushing phenology of chimpanzee food plants were investigated monthly for 51 months (between May 1997 and July 2001) in the lowland forest of Mahale Mountains National Park, Tanzania. Data on feeding and grouping by chimpanzees were also collected (between August 1997 and July 1998) to examine the relationship with food availability.
Chimpanzees responded flexibly to the distinct seasonal fluctuation in fruit food availability, and kept a high feeding rate (>50%) on fruits throughout the year. However, when we limited the analyses of fruit food species to those species that were sampled for the phenological survey, the relative dependence on fruits fluctuated in accordance with fruit availability. Fruiting tended to peak from the drought to early wet season, and this trend was especially pronounced in the major fruit food species. One liana species in particular, Saba comorensis, which has the highest density in the forest, affected the intensity of the fruiting peaks. Chimpanzees spent 10% of their total feeding time on this fruit. They began eating the Saba fruit before its fruiting peak until it stopped fruiting completely. THV and arboreal leaves were eaten in both high and low fruiting seasons. Monthly mean group size was estimated by different methods. Only the mean number of individuals who were assumed to participate in daily ranging activity positively correlated with fruit food availability, while no correlation was found between food availability and the number of individuals who actually or potentially shared the same food resource at the same place.
Dispersal of Aglaia spectabilis, a Large-seeded Tree Species in a Moist Evergreen Forest in Thailand
Center for Ecological Research, Kyoto University, Japan
School of Environmental Science, The University of Shiga Prefecture, Japan
Research Institute for Humanity and Nature, Japan
Hornbill Project, Department of Microbiology, Mahidol University, Thailand
Department of Human and Culture, Musashi University, Nerima, Japan
National Park, Wildlife and Plant Conservation Department, Thailand
We investigated the seed dispersal of Aglaia spectabilis (Meliaceae), a large-seeded tree species in a moist evergreen forest of Khao Yai National Park in Thailand. Although one to one relationships between frugivores and plants are very unlikely, large-seeded plants having to rely on few large frugivores and therefore on limited disperser assemblages, might be vulnerable to extinction. We assessed both the frugivore assemblages foraging on arillate seeds of Aglaia spectabilis and dispersing them and the predator assemblages thereby covering dispersal as well as the post-dispersal aspects such as seed predation. Our results showed that frugivores dispersing seeds where a rather limited set of four hornbill (Buceros bicornis, Aceros undulatus, Anorrhinus austeni and Anthracoceros albirostris) and one pigeon species (Ducula badia), whereas two squirrel species (Ratufa bicolor and Callosciurus finlaysonii) were not dispersers, but dropped the seeds on the ground. Three mammal species (Hystrix brachyura, Maxomys surifer and Callosciurus finlaysonii) were identified as seed predators on the forest floor. High seed predation by mammals together with high seed removal rates, short visiting times and regurgitation of intact seeds by mainly hornbills lead us to the conclusion that hornbills show high effectiveness in dispersal of this tree species.
A Preliminary Research on Ant Fauna in a Habitat of Chimpanzees, Kalinzu Forest, Uganda
Kyoto University, Japan
The driver ant Dorylus molestus is an important food source for the ant-dipping chimpanzees in the Kalinzu Forest Reserve, Uganda. We studied ant fauna at Kalinzu to examine the chimpanzees°« preference among a variety of ants, including driver ants. This is the first attempt to investigate the background ant fauna at a chimpanzee study site by using a standardized protocol (modified Quadra). This protocol is a combination of four techniques: hand collecting, leaf litter sifting, soil core sampling, and honey bait trapping. This technique made it possible to collect many species within short period of time for comparison with those obtained in different localities/habitats. In addition to the standard protocol, general collecting was also conducted whenever different species of ants were observed in the forest. All four species of Dorylus could be collected solely through general collecting. The total number of species collected by the two methods was 102 species belonging to 31 genera (eight subfamilies), corresponding to 37.8% of those (82 genera) known to exist in the entire Afrotoropical region. Twelve Camponotus and six Crematogaster species were included in the collection; these two genera have been reportedly to be eaten by chimpanzees at other study sites, but they have not been investigated well enough as a part of the chimpanzee diet at Kalinzu. In addition to clarifying the diet of chimpanzees, the precise ant fauna and these species°« availability should be studied by using compatible methods (protocol and general collecting) to reveal the chimpanzees°« preference for particular ants.
Social Correlates of Posture in Wild Chimpanzees
Department of Biological Sciences School of Science, Tokyo University, Japan
Previously, posture in wild chimpanzees has been studied mainly from the standpoint of physical anthropology (e.g., the origin of bipedalism). On the other hand, ethological studies highlighted the influences of ecological or social risk on the animal posture and showed that animals 'relax' their posture when those risks are low. Unfortunately, those ethological perspectives have not been fully introduced into primate posture studies. To fill those gaps and investigate in what situation the wild chimpanzees 'relax' their posture (i.e., lying), I studied wild chimpanzees (Pan troglodytes schweinfurthii) of M-group at the Mahale Mountains National Park in western Tanzania. I observed all 9 adult males and 9 adult females by the focal animal sampling method. During focal observations, I recorded posture of the focal individual every 5mins by the instantaneous sampling method. I analyzed the data when the focal chimpanzee was on the ground. Using Generalized Linear Mixed Model, I found that the number of the group members in proximity influenced the likelihood that the focal chimpanzee lay. That is, chimpanzees lay less frequently as the number of group member in proximity (3m) increased. This suggests that within-group density, which related to the risk of the aggression, affects the posture in wild chimpanzees.
Proximity and Estrous Synchrony in Mahale Chimpanzees
Okinawa University, Japan
Kyusyu University, Japan
The pioneering work by McClintock 30 years ago opened new avenues in the study of menstrual and oestrus synchrony in female mammals. One of the proximate factors suggested is spatial proximity or having an environment in common among females. However, most studies on estrous synchrony have been reported from limited space as enclosure. This study analyzed the relationship between proximity and estrous synchrony by using one year data of wild female chimpanzees at Mahale. There were two pairs of high proximity in cycling females. We compared synchronic index between those two pairs and others. The results showed that the synchrony index of high proximity pairs did not differ significantly from those of other pairs.
A Preliminary Report on the "Lost Child" and the Isolation Calls in Wild Chimpanzees at Mahale
Laboratory of Human Evolution Studies, Graduate School of Science, Kyoto University, Japan
Mahale Mountains Chimpanzee Research Project, Tanzania
The isolation call is produced by immature individuals of many primate species, when they are separated from their mothers. Chimpanzee infants and juveniles, when they have lost sight of their mothers, produce some kinds of "distress" vocalizations: "whimper", "scream" and/or "pant hoot". Isolation calls are easily changed from one of these to another, or are sometimes intergraded among these vocalizations. Isolation calls are generally thought as vocal signals requesting the mother to come to the site of the calling child. However, the chimpanzee mother occasionally does not appear at the site of the calling child. So far, the responses of chimpanzee mothers to the calls have not been studied systematically.
The purpose of this study is to clarify the functions of isolation calls and how mother and child communicate with vocalizations when they are separated. For this purpose, we conducted focal observation of mother-child pair; Matsusaka observed a child, while Kabumbe observed its mother. The subjects were the M group chimpanzees living in the Mahale Mountains National Park, Tanzania. The study period was from November 2002 to October 2003. The focal immature chimpanzees included 2 juvenile males, 1 juvenile female, 6 infant males and 7 infant females. This presentation reports the preliminary results on (1) the frequency of occurrence of the isolation calls in immature chimpanzees and (2) the responses of the mothers to the isolation calls. Results showed that (1) the isolation calls were most frequently emitted by 3-4 years old infants and that (2) the mother often did not respond to the child's isolation calls; she often did not move towards the child's site nor emit vocalizations to manifest her location immediately after the child's calls.
Residential group of Babongo Pygmies in southern Gabon
Lab. of Human Evolution Studies, Graduate School of Science, Kyoto University
Many anthropological research projects on The Forest Peoples, or Pygmies, have been conducted since the 1960°«s. However, few studies have been made in Gabon until recently.
I surveyed three ethnic groups in the period of 2002-2003: Baka in the north, Bakoya (Bakola) in the northeast, and Babongo in the central and the south. Generally, they live in sedentary settlements along the roadside, and agriculture has penetrated deeply into their lives. This tendency was reported in the 1940°«s, which was a relatively earlier development compared with other areas.
I investigated their subsistence activities and residential patterns by living in a Babongo village from July to October 2003. While they still engaged in hunting, gathering and fishing, they depended mainly on agricultural resources. Commercial activities such as selling natural resources and wage labor were also observed. As for their residential patterns, the village consisted of semi-permanent houses that were similar to their neighboring farmers. Despite their sedentary settlement, they went hunting or fishing in the forest and spent several days there. They also visited each other by traveling among neighboring villages. The membership of this village varied with their daily activities in this study period, ranging from 7 to 39 (average 26) in number.
The Pygmies currently living in Gabon would not likely be classified as °»hunter-gatherers°… in terms of their subsistence activities. However, they seem to maintain flexibility in their social organization, which we can assume was developed through their traditional hunting and gathering lifestyle.
The Trap-Tube Problem : An Alternative Approach
Max-Planck Insitute for Evolutionary Anthropology, Germany
There is much debate as to whether primates have a causal understanding of the physical world. One experiment which has added fuel to the fire is the trap-tube problem. The experiment involves having a Plexiglas tube containing a trap in its centre. A reward is placed on one side of the trap and the subject is given a tool. In order to retrieve the reward the subject has to avoid pushing it into the trap. There have been three trap-tube experiments conducted on primates: one on capuchin monkeys and two on chimpanzees. In each of these experiments some subjects learnt to solve the problem, but only after many trials. It is therefore unclear whether subjects had developed a causal understanding of the problem or if they had formed a procedural rule, such as always push the reward away from the trap. This possibility was tested in two of these experiments by rotating the tube 1800 so that the trap was now pointing upwards and unable to hinder the subject's retrieval of the reward. The results indicated that the subjects were using a procedural rule to solve the task. However, we feel that the experimental design may have been too limited to investigate whether subjects understood the problem in causal terms. We therefore presented the tube-trap problem to four species of great apes, with a slightly modified control condition. In addition, unlike the previous experiments, we allowed the subjects the opportunity to execute a more natural tool-use behaviour: raking the reward out of the tube as opposed to pushing it. The preliminary results indicated that one subject (an orangutan) understood the causal nature of the problem.
Consortship in Chimpanzees at Bossou
PRI, Kyoto University, Japan
The present study is a preliminary report focusing on the behavioral patterns during the consortship of chimpanzees at Bossou, Guinea, West Africa.°°In the consortship, an adult male took an estrous female to a peripheral area of the community range. Few previous studies have ever revealed the behavioral characteristics of the chimpanzees in the consortship period probably because of the difficulty of observing the consort pairs. I followed an alpha male (22 year old) of Bossou community for 8 months in 2002 to 2003 to record the behaviors from nest to nest in all occurrences sampling. I carried GPS to measure the location of the target male every minute. In addition, other assistants simultaneously followed the other two individuals with GPS from nest to nest. These GPS data provided the information on the spatial distance among three target individuals every minute. The results were summarized as follows. Two males (alpha male and beta male) were almost always located within 1500m in the non-consortship period. However, the distance between the two males became much longer in the consortship period, ranging from 1000 to 4200m. The alpha male normally moved about 4 km per day on the average in the non-consortship period. In contrast, the travel distance per day of alpha male significantly decreased, at most 2 km, in the consortship period. However, there was no significant difference on the proportion of feeding time in both periods although the travel distance was greatly reduced in the consortship period. These findings may indicate that the alpha male concentrates on mating and avoids feeding competition in the consortship period by keeping himself and his mate away from the other chimpanzees.
How Do Female Chimpanzees See the Dominance Relationship among Males? : Measured by Pant-Grunt Vocalizations
Kyoto University, Japan
Pant-grunt vocalization is a formal signal of the subordinate status in a chimpanzee unit-group. Generally, adult males receive pant-grunts from all adult females. Whether or not adult females pant-grunt to higher ranking males more often than to lower ranking ones was studied. During the study period from 1999 to 2000, in the Mahale Mountains National Park, Tanzania, adult males' ranks were classified into three categories, the first-ranking, high-ranking, and low-ranking, on the basis of the analyses of the directions of pant-grunts among adult males. Adult females pant-grunted to the first-ranking male more often than the others, but such tendency was not apparent between high- and low-ranking ones. In 112 cases in which an adult female pant-grunted in a situation where two or more adult males were present, only one male was pant-grunted to in 89 cases (79%). When the first- and low-ranking males were present, only the first-ranking one was almost always pant-grunted to. On the other hand, a higher ranking male was not always pant-grunted to when the first- and high-ranking males were present, and when high- and low-ranking males were present.
On the Pant-hoot Chorusing Behavior of Male and Female Chimpanzees in the Mahale Mountains National Park, Tanzania
Kyoto University, Japan
The pant-hoot is known as a chimpanzees°« species specific long-distance call, and both males and females emit the call with the °∆climax°« part.
The function of chimpanzee°«s pant-hooting behavior seems to be multiple: One of the previous studies suggested that male pant-hoot functions to recruit associates or allies of the emitter. The other suggested that the function is to broadcast the information of food resource. These studies have treated the data as if each pant-hoot by an individual was independent, even when pant-hoot is emitted simultaneously.
It is known that two or more chimpanzees frequently emit pant-hoots simultaneously. This phenomenon is called the pant-hoot chorus. Regarding the chorus in chimpanzees, previous studies have mainly focused on the acoustic feature, and very few studies have refereed to the sociality found in chorus, such as relationship among the chorus partners.
To understand this phenomenon, I hypothesized one of the functions of pant-hoot chorusing behavior may be to manifest the relationship between chorusing partner.
One of the benefit to manifest their relationship is to strengthen the bond of their relationship. Thus, it is predicted that the relationship between chorusing partners may reflect their close relationship: Chimpanzees chorus pant-hoot with their close companion more frequently than with non-close companion.
To test this hypothesis, I analyzed the social context when male and female chimpanzees emit pant-hoots, chorusing partner and some social relationship between focal individuals (8 males and 8 females), using 5 months data of field study in the Mahale Mountains National Park, Tanzania.
In male-male choruses, allies and associates tended to chorus more frequently than the other pairs, and most of male-female choruses included pant-hoots of alpha male. These results are suggested to support the hypothesis.
Long call and its effect on grouping patterns in wild spider monkeys.
PRI, Kyoto University
Spider monkeys exhibit fission-fusion social organization. They have a vocalization called "long call" which is exchanged between intra and inter groups over distances. Field studies on wild long-haired spider monkeys (Ateles belzebuth belzebuth) at La Macarena, Colombia clarified sex differences in frequency of long call emission, and its effect on grouping patterns. It has been reported that spider monkey females are more vocal than males, but this research showed that male spider monkeys emitted long calls more frequently than females. Both males and females in smaller parties emitted long calls more frequently than those in larger parties. In case of males, party size significantly enlarged within 30 minutes after long call emission, but not in case of females. As male spider monkeys were found in larger parties than females, long call may have function as a cohesion call among dispersed individuals in the course of large-party formation.
Preliminary results on the dietary differences between two sympatric populations of gorillas and chimpanzees using stable isotope ratio analysis
Kyoto University, Japan
Chimpanzee and gorilla hair samples collected from night nests at two sympatric populations of two different forest habitats in Gabon were analyzed for carbon and nitrogen stable isotope ratios represented as ¶ń13C and¶ń15N values. The first habitat at Petit Loango is a coastal forest characterized by scarce terrestrial herbaceous vegetation (THV) such as Marantaceae and Zingiberaceae. The second at Moukalaba is a secondary forest that had been logged selectively for years. Although the two sites are located within 100 km of each other and the forests are composed of a number of the same plant species, the¶ń15N values indicate the apes fed on considerably different food resources between the sites. In addition, the¶ń13C values indicate that the dietary differences between the two ape species were distinguishable in both sites. Moreover, the extent of the differences between the two species can be evaluated and compared between the populations. Results reveal that the difference in their diet between the two apes appeared to be larger in the habitat with less THV than in the other habitat, and also chimpanzees seemed to use more similar food resources between the two sites than gorillas. Although the sample size of each group is still small in the present study, these preliminary results demonstrate the use of stable isotope ratios of carbon and nitrogen for indicating the extent of dietary differences between gorillas and chimpanzees and also between different habitats.
Feeding Responses to Seasonal Changes in Food Supply in the Forest Analyzed by Fecal Samples in Bossou, Guinea
Kyoto University, Japan
Feeding habits of Bossou chimpanzees were investigated by fecal analysis andcompared with other chimpanzees research sites regarding response to fluctuations of fruit availability in the habitat, where presented by similar methods. Overall diet of Bossou chimpanzees showed the highest diversity of fruit species per dung and seasonal change in volume index of fruit content showed the strongest correlation with fruit availability among research sites compared. This means that chimpanzees in Bossou can utilize products of the forest thoroughly because there are no feeding competitions with other species owing to the rack of frugivores as well as other primate species in Bossou forest.
Density estimate of Western gorillas by a new census method in the Moukalaba-Doudou National Park, Gabon
Kyoto University, Japan
Population density of western gorillas (Gorilla g. gorilla) in the Moukalaba-Doudou National Park, southwestern Gabon, is estimated by using a new census method. Dung piles were counted along transect lines set up in areas of each type of vegetation during September and October 2002. This method requires a smaller cost than the marked nest count methods previously used for density estimates of the great apes, and discrimination of gorilla dung piles from chimpanzee dung piles is much easier than discrimination of gorilla nests from chimpanzee nests. It is thus suggested that the dung count method is appropriate for western gorilla population monitoring. We estimated 5.44 gorillas / km2 (3.97 - 7.46 gorillas /km2) in the northern part of the park, which is the highest density among gorilla populations. Low pressure of human hunting may constitute a primary cause of such high density, and high food tree density, relatively low chimpanzee density, and scarce density of colobine monkeys may also support survival of gorillas in the habitat with low herbaceous vegetation, which characterizes this national park.
Naturally Acquired Retrovirus Infections from Gorilla (Gorilla Gorilla), Mandrill (Mandrillus Sphinx), and De Brazza°«s Guenon (Cercopithecus Neglectus) among Central African Hunters
1Departments of Epidemiology, 2International Health, and 3Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, U.S.A.
4 HIV and Retrovirology Branch, Division of AIDS, STD, and TB Laboratory Research, National Center for HIV/AIDS, STD, and TB Prevention, ?Centers for Disease Control and Prevention, U.S.A.
5 Henry M. Jackson Foundation, U.S.A.
6 Army Health Research Center, Cameroon
7 Walter Reed Army Institute of Research, U.S.A.
Background: The hunting and butchering of wild nonhuman primates (NHPs) infected with simian immunodeficiency virus (SIV) is thought to have sparked human immunodeficiency virus (HIV), perhaps the most significant pandemic in human history. Nevertheless, while SIV and other primate retroviruses infect laboratory and zoo workers, zoonotic retrovirus transmission has never been documented in natural settings.
Methods: Behavioral data, plasma and peripheral blood lympocytes (PBLs) were collected from individuals living in rural villages in Cameroon. Serology, PCR and sequence analysis were used to obtain evidence of retrovirus infection.
Results: Zoonotic infections with simian foamy virus (SFV), a retrovirus endemic in most Old World primates, were found among people living in Central African forests and reporting direct contact with blood and body fluids of wild NHPs. Of 1,099 individuals tested, 10 (0.9%) were found to have antibodies to SFV. Sequence analysis from these individuals revealed three geographically independent human SFV infections, each of which was acquired from a distinct NHP lineage: De Brazza°«s guenon (Cercopithecus neglectus), mandrill (Mandrillus sphinx), and gorilla (Gorilla gorilla), two of which (De Brazza°«s and mandrill) are naturally infected with SIV.
Discussion: The results demonstrate that retroviruses are actively crossing into human ?populations, and suggest that a number of people living in Central Africa are currently infected with SFV. The results suggest that contact with NHPs, such as occurs during hunting and butchering, can play a role in the emergence of human retroviruses and that the reduction of primate bushmeat hunting may have important consequences for disease emergence.
Ant-dipping Behavior for Carpenter Ants (Camponotus Brutus) by Bossou Chimpanzees
Graduate School of Asian and African Area Studies, Kyoto University, Japan
Bossou chimpanzees has been observed to dip terrestrial driver ants with a stout wand. In contrast, Mahale chimpanzees are specialized in "fishing" arboreal carpenter ants with a flexible tool. Although the behavioral patterns are roughly similar, important differences found between the two behaviors (e.g. ant species, location, tool property), and moreover the absence of corresponding behavior in each site (ant-fishing in Bossou and ant-dipping in Mahale) illustrate subtle but profound variety of chimpanzee cultures. In 2003, I observed°»ant dipping°…behavior for arboreal carpenter ants (Camponotus brutus) by a Bossou chimpanzee juvenile. Although the ant species was identical and nest location was similar to those in Mahale, tool property and behavioral details were more similar to those of driver ant dipping at Bossou. Coupled with two previous incomplete observations of carpenter ant dipping at Bossou, and more than 20 years observations of the absence in adults, it is suggested that the behavior is restricted in juvenile/adolescents. Considering the frequency of this behavior, it is unlikely that the behavioral knowledge has been maintained through social learning. The behavior may be a technical application of the mainstream driver ant dipping by enterprising young individuals.
Reciprocity of Object Removing Movements in Grooming among Chimpanzees at Mahale Mountains National Park, Tanzania
PRI, Kyoto University, Japan
The number of object removing movements (ORM), the measure for evaluating benefit of grooming used here, and the duration of grooming were investigated among wild chimpanzees of M group in the Mahale Mountains National Park, Tanzania. An adult male chimpanzee Fanana (FN), the then alpha male of this group, was groomed 2.9 times longer than he groomed others. However, the number of ORM by FN while being grooming was 0.8 times as many as that when grooming others. FN showed a higher rate of ORM per duration of grooming than the other five focal animals (three adult females and two adult males), but not a higher level of self grooming. I suggest that FN improved efficiency of ORM to correct for the imbalance of the duration of time between grooming and being groomed. This suggests that chimpanzees regard ORM as a benefit of grooming and understand the balance of grooming.
Reciprocity of Object Removing Movements in Grooming among Chimpanzees at Mahale Mountains National Park, Tanzania
Kyoto University, Japan
The lower waist-to-hip Ratio (WHR) is regarded as indicate of high fertility. Singh (1993) asserted that men have an innate preference for women of lower WHR, regardless of weight. This hypothesis is called the WHR hypothesis. However, some studies on hunter-gatherer men who were not exposed to western culture showed that they did not prefer women of lower WHR. Subsequently, Yu and Shepard (1998) asserted that this preference for lower WHR showed the influence of western media (IWM). In this study, I examined Japanese preference for female body shapes.
I used a set of questionnaires that was composed of a series of stimuli. The series of stimuli is consisted of 12 line drawings of female figures representing four levels of WHR (0.6, 0.7, 0.8, 0.9) and three levels of body weight (thin, normal, obesity). Subjects were required to indicate their highest three and lowest three rankings each for °»sexy°… which concept was came from West and °»preference as lover°…. Male subjects were required to give their own evaluations, while female subjects were required to indicate what they thought of °»Men°«s general evaluation°….
In the evaluation of °»sexy°…, the lower WHR was highly evaluated both by men and women, excepting for that there was no difference between 0.6 and 0.7 in men. In the evaluation of °»preference as lover°…, such tendency was not seen both in men and women, but 0.9 was lower evaluation than the other WHRs. In these men°«s results, evaluation of °»preference as lover°… did not support the WHR hypothesis, while the evaluation of °»sexy°… showed the aesthetic-preference that was resulted from IWM as well as the innate preference that was resulted from WHR hypothesis. This difference of evaluations between two questions was also shown in the women°«s results. Therefore, it suggested to be shown that one of °»sexy°… was effected by IWM, but another of °»preference as lover°… was not. Consequently, it is suggested that not only hunter-gatherer men but also Japanese men who have been exposed to western culture do not have the innate preference for women of lower WHR.