Body weights of wild chimpanzees (Pan troglodytes schweinfurthii) of the Mahale Mountains National Park, Tanzania

Ten male and nine female habituated chimpanzees (Pan troglodytes schweinfurthii) in the Kasoje area of the Mahale Mountains National Park, Tanzania, were weighed intermittently between December 1973 and March 1980 by luring them up a rope hung on a spring balance: six adult males averaged 42.0 kg and eight adult females 35.2 kg. Seasonal change in body weight was recognized at least partially; body weights tended to decrease in the later part of the wet season presumably because of food shortage in the middle of the wet season. Comparison of body weight among three populations of the same subspecies suggests that adult female chimpanzees of Mahale appear to be heavier than those of the Gombe National Park, Tanzania, and that they seem to be similar to the forest-living counterparts of eastern Zaire. On the other hand, body weights of adult male chimpanzees from the three populations do not show significant differences. Perhaps feeding competition among adult females in a small, isolated habitat is more severe than that among adult males, which may result in the body weight reduction among adult female chimpanzees at Gombe.     

Diet of wild chimpanzees (Pan troglodytes verus) at Mt. Assirik,Senegal: I. Composition

The composition of the diet of a savanna-living population of wild chimpanzees (Pan troglodytes verus) at Mt. Assirik in Senegal is presented. The study site had a prolonged dry season, high temperatures, and vegetation dominated by grasses. Data came from direct observation, fecal specimens, and feeding traces; thus, strict criteria for acceptance of the indirect data were specified. Composition of diet was given in terms of species and family of prey, parts eaten, life-form, type of habitat, and criteria for inclusion. Forty-three species of plants with 60 parts were eaten; mostly fruits, from trees, in woodland. Nine species of animal prey were eaten, mostly social insects. An additional 41 species of plants with 53 parts were classed as likely to be eaten by chimpanzees, mostly on the grounds of their being eaten by sympatric anthropoids. Overall, the diet of the apes at Mt. Assirik resembles that of this species elsewhere in Africa, but the size of the dietary repertoire seems small and the proportion of low-quality foodstuffs high. The latter are mostly time-consuming to collect or tedious to obtain or process, and include underground storage organs.     

Fecal bacterial diversity of human‐habituated wild chimpanzees (Pan troglodytes schweinfurthii) at Mahale Mountains National Park,Western Tanzania

Although the intestinal flora of chimpanzees has not been studied, insight into this dynamic environment can be obtained through studies on their feces. We analyzed fecal samples from human‐habituated, wild chimpanzees at Mahale Mountains National Park, Tanzania, and compared microbial community profiles to determine if members of the same social group were similar. Between July and December 2007, we collected fresh fecal samples from 12 individuals: four juveniles, four adolescents, and four adults, including three parent–offspring pairs. Each sample was analyzed using Terminal‐Restriction Fragment Length Polymorphism of amplified 16S rRNA genes. Twelve different profiles were generated, having between 1 and 15 Terminal‐Restriction Fragments (T‐RFs). Overall, a total of 23 different T‐RFs were produced. Putative assignments of T‐RFs corresponded to the phyla Firmicutes (Clostridia, Bacilli, and Lactobacilli), Bacteroidetes, Tenericutes (Mollicutes Class), Actinobacteria, and Proteobacteria, as well as to uncultured or unidentified organisms. Firmicutes and Bacteroidetes phyla and Mollicutes Class were the most commonly assigned in 11, 8, and 8 of the samples, respectively, with this being the first report of Mollicutes in wild chimpanzees. Principal Components Analysis (PCA) revealed clustering of nine samples, and 80.5% of the diversity was accounted for by three samples. Morisita indices of community similarity ranged between 0.00 and 0.89, with dissimiliarity (<0.5) between most samples when compared two at a time. Our findings suggest that, although phylotypes are common among individuals, profiles among members of the same social group are host‐specific. We conclude that factors other than social group, such as kinship and age, may influence fecal bacterial profiles of wild chimpanzees, and recommend that additional studies be conducted. Am. J. Primatol. 72:566–574, 2010. © 2010 Wiley‐Liss, Inc.     

Use of a tool-set by Pan troglodytes troglodytes to obtain termites (Macrotermes) in the periphery of the Dja Biosphere Reserve, southeast Cameroon

At the northern periphery of the Dja Biosphere Reserve (southeastern Cameroon) we recorded a new use of a tool-set by Pan troglodytes troglodytes to prey on Macrotermes muelleri, M. renouxi, M. lilljeborgi, and M. nobilis. We recovered 79 puncturing sticks and 47 fishing probes at 17 termite nests between 2002 and 2005. The mean length of the puncturing sticks (n = 77) and fishing probes (n = 45) was 52 cm and 56 cm, respectively, and the mean diameter was 9 mm and 4.5 mm, respectively. Sixty-eight percent of 138 chimpanzee fecal samples contained major soldiers of four Macrotermes species. The chimpanzees in southeastern Cameroon appeared to be selective in their choice of plant material to make their tools. The tools found at our study site resemble those from other sites in this region. However, in southeastern Cameroon only one tool-set type was found, whereas two tool-set types have been reported in Congo. Our study suggests that, along with the different vegetation types and the availability of plant material around termite nests, the nest and gallery structure and foraging behavior of the different Macrotermes spp. at all Central African sites must be investigated before we can attribute differences in tool-use behavior to culture.     

Ecological context of savanna chimpanzee (Pan troglodytes verus) termite fishing at Fongoli, Senegal

Chimpanzees (Pan troglodytes verus) at Fongoli, Senegal, consume termites year-round. Understanding the ecological context behind this behavior is especially important in light of the environmental conditions at Fongoli. This mosaic savanna habitat is one of the hottest and driest sites where chimpanzees have been studied. Two genera and four species of termites were found in association with tools used by chimpanzees in a sample of 124 termite mounds that were monitored. The chimpanzees of Fongoli termite fish predominantly in woodland and forest habitat types, and, although woodland accounts for the majority of the chimpanzees' home range, forest habitat types comprise only about 4% of their range. Thus, habitat type has an influence on the Fongoli chimpanzees' termite fishing. Termite consumption to the degree seen at Fongoli may have particular significance for hominid evolution, given the expansion of Pliocene hominids into increasingly open, hot, and dry habitats.     

Characterization of 15 single nucleotide polymorphism markers for chimpanzees (Pan troglodytes)

We report the characterization of 15 new single nucleotide polymorphism markers for a threatened species, the chimpanzee (Pan troglodytes), developed using a targeted gene approach. These markers are derived from the Y chromosome and autosomal regions of the genome and show frequency differences between chimpanzee subspecies from central and western Africa. These single nucleotide polymorphism markers are the first to be designed for the genotyping of wild chimpanzee populations and will provide a useful addition to the genetic tools employed for the conservation management of this threatened species.     

Newly acquired feeding habits among the chimpanzees of the Mahale Mountains National Park,Tanzania

The M group chimpanzees (Pan troglodytes schweinfurthii) of the Mahale Mountains National Park, Tanzania, began to feed on three agricultural fruit species, guava, mango and lemon. It took them 7–8 years until they began to taste these fruits since the villagers left the park area in 1974. Although adult chimpanzees are conservative in their feeding habits, they are capable of rapidly acquiring new feeding habits, or new traditions, once they notice that the food is suitable.     

Sources of variation in the nesting behavior of chimpanzees (Pan troglodytes schweinfurthii) in the Budongo forest, Uganda

Data on nesting behavior and nests of the Sonso community of chimpanzees (Pan troglodytes schweinfurthii) living in the Budongo Forest, Uganda, were collected between October 1995 and December 1996. Analysis of the selection of nests shows a preference for particular tree species, especially Cynometra alexandri. Male chimpanzees nested lower than females. Day nests were found to be structurally simpler than night nests and were built in tree species used for feeding, at the same height as feeding activity. Day and night nests serve different functions, and should be clearly distinguished in studies of nesting behavior.     

Social behavior and genital swelling in pregnant chimpanzees (Pan troglodytes)

Previous reports of increased sexual activity associated with genital swelling during chimpanzee pregnancy have suggested that the tumescent pregnant female may be regarded as a regularly cycling estrous female. Analysis of additional data from seven pregnant and eight cycling females, however, indicated that tumescent pregnant females differed from cycling females in some social interactions with males. As in earlier reports, pregnant females were more receptive to male-initiated copulatory bouts. In addition, pregnant females initiated grooming bouts with males much less frequently than did cycling females, and males spent less time grooming and less frequently inspected the genitals of pregnant than cycling cagemates. This tendency to decrease social interaction during pregnancy is consistent with field reports that pregnant chimpanzees prefer the company of their offspring and other noncycling females. In addition, the genital swelling patterns of 40 chimpanzee pregnancies were analyzed. Length of gestation averaged 231.5 days. Although a high degree of individual variation existed, females were swollen an average of 41% of the days observed, yet reached maximum swelling only 8.7% of the time. Genital swelling was less frequent during the third trimester, averaging 50.5, 47.9, and 22.6% tumescent days in each trimester. Young pregnant females showed maximum swelling more often than did older females. This finding is discussed with respect to field reports of intercommunity transfer of young, tumescent female chimpanzees.     

Nipple contact in captive black-faced chimpanzees (Pan t troglodytes [Blumenbach, 1779])

Three chimpanzee (Pan t troglodytes) mother-infant dyads were studied from months 3 to 11 of the infants' lives in order to obtain data on nipple contact. Three conclusions were obtained: (1) There were fluctuations in the time spent in nipple contact. (2) Both female offspring were in nipple position for less time than the male offspring. (3) Grooming of the infants by their mothers during nipple contact was observed more frequently in the mother-female offspring pairs.     

Focal epithelial hyperplasia of the oral mucosa in two chimpanzees (Pan troglodytes)

Papillomas in the oral mucosa compatible with focal epithelial hyperplasia are reported in two chimpanzees. The lesions were studied by light and electron microscopy. Virus particles were not observed. The literature dealing with focal epithelial hyperplasia in humans and other animals is reviewed.     

Grips and hand movements of chimpanzees during feeding in Mahale Mountains National Park,Tanzania

It has long been assumed that stone tool making was a major factor in the evolution of derived hominin hand morphology. However, stresses on the hand associated with food retrieval and processing also have been recognized as relevant early hominin behaviors that should be investigated. To this end, chimpanzee food manipulation was videotaped in the Mahale Mountains National Park, Tanzania. Grips and hand movements by 39 chimpanzees were analyzed for arboreal and terrestrial feeding involving 10 food‐types and associated vegetation. It was predicted that (1) new grips would be found that had not been observed in captivity, (2) forceful precision grips would be absent from the repertoire, as in captivity, and (3) precision handling would be observed. New grips involving the full thumb and buttressed index finger, and a new integrated pattern of grips and forceful hand movements were discovered, associated with feeding on large fruits and meat. Participation of the full thumb in these grips, rather than the distal thumb and fingers, throws light on feeding behaviors that may have become increasingly significant factors in the evolution of derived hominin thumb morphology. The proximal thumb stabilizes food with the flexed index finger against the pull of the teeth and provides leverage in breaking food into portions. Isolated qualitative observations of possibly forceful pinch by the thumb and side of the index finger highlight the need for comparative quantitative data to test whether humans are unique in forceful precision gripping capability. Precision handling was not seen. Am J Phys Anthropol 156:317–326, 2015. © 2014 Wiley Periodicals, Inc.     

Association partners of young chimpanzees in the Mahale Mountains National Park,Tanzania

Association partners of young chimpanzees at the Mahale Mountains National Park were analyzed. Juvenile and adolescent chimpanzees associated frequently with their mothers, although mother-offspring association decreased as the offspring grew up. Males tended to leave their mothers and associate with adult males, while females remained frequently associating with their mothers in early adolescence. In late adolescence and young adulthood, males usually associated with adult males and cycling adult females. Females may transfer into neighboring unit-groups in this stage. Although an immigrant female tended to be alone when her estrous cycle stopped, she associated with many individuals, in particular with adult males, when she resumed cycling. Some orphans were observed to associate frequently with particular adults. The findings were discussed in relation to the unique characteristics of chimpanzee social system.     

Polymerase chain reaction detection of Clostridium perfringens in feces from captive and wild chimpanzees, Pan troglodytes

Background For veterinary management of non‐human primates in captivity, and conservation of wild‐living primates, management of their health risks is necessary. Incidences of pathogenic bacteria in the fecal specimens are considered as one of the useful indicators for non‐invasive health monitoring. Methods We carried out the detection of Clostridium perfringens in feces from captive and wild chimpanzees by the rapid polymerase chain reaction method. Results The bacterium was detected in most fecal specimens (80%) in captive chimpanzees. Contrarily, the detection rate in the wild chimpanzees was low, with 23% (n = 12) of 53 fecal samples from the Bossou group, Guinea, and 1.2% (1/81) in the Mahale group, Tanzania. Conclusions These results show that the intestinal microflora differs between Pan populations under various living conditions, being influenced by their diet and environment.     

Elemental variation in the termite fishing of wild chimpanzees (Pan troglodytes)

Chimpanzee tool behaviours vary dramatically in their complexity and extent of geographical distribution. The use of tool sets with specific design features to gather termites extends across a large portion of central Africa. Detailed examination of the composition and uniformity of such complex tool tasks has the potential to advance our understanding of the cognitive capabilities of tool users and processes underlying the maintenance of technological skills. In this study, we examined variation in chimpanzee tool use in termite gathering from video-recorded sequences that were scored to the level of functionally distinct behavioural elements. Overall, we found a high degree of similarity in tool-using techniques exhibited by individuals in this population. The number of elements in each individual's repertoire often exceeded that necessary to accomplish the task, with consistent differences in repertoire sizes between age classes. Adults and subadults had the largest repertoires and more consistently exhibited element strings than younger individuals. Larger repertoires were typically associated with incorporation of rare variants, some of which indicate flexibility and intelligence. These tool using apes aid us in understanding the evolution of technology, including that of our human ancestors, which showed a high degree of uniformity over large spatial scales.     

Developing classification in action: II. Young chimpanzees (Pan troglodytes)

The development of spontaneous object manipulation in 5 chimpanzees (Pan troglodytes) from ages 15 to 54 months was investigated, focusing on formal properties of subjects’ acts and the objects they manipulated. Young chimpanzees’ manipulation progress from serial one-at-a-time acts on one object to parallel two-at-a-time acts on two or more objects. With age, simultaneous acts become increasingly transformational and identical or reciprocal to each other. Moreover, the class properties of objects manipulated simultaneously change. When presented with objects belonging to two different classes, subjects shift, with age, from manipulating different objects to manipulating identical or similar objects. In all these respects young chimpanzee’ development is similar to human infants’. In others it differs. Most especially, the onset age is later and the development is slower as well as less structurally complex.     

Foreign body urethral obstruction in a chimpanzee (Pan troglodytes)

Background  A 34-year-old, captive-born, vasectomized male chimpanzee ( Pan troglodytes ) presented with lethargy and scrotal swelling.
Methods  Urethral obstruction was diagnosed via urethroscopy.
Results  Removal of the grass stem foreign body resolved the obstruction. Scrotal and preputial ulceration developed from urine scald, which was managed with surgical debridement and antibiotics.
Conclusions  After 7 weeks, the animal was reintroduced to its troup and has been healthy for 11 months.