Chimpanzee Food Research Articles

The behavioral ecology of sympatric African apes: implications for understanding fossil hominoid ecology

The behavioral ecology of the great apes is key evidence used in the reconstruction of the behavior of extinct ape and hominid taxa. Chimpanzees and gorillas have been studied in detail in the wild, and some studies of their behavioral ecology in sympatry have also been been carried out. Although the two ape species have divergent behavior and ecology in important respects, recent studies have shown that the interspecific differences are not as stark as previously thought and subsequently urge new consideration of how they share forest resources when sympatric. These new data require re-examination of assumptions about key aspects of chimpanzee-gorilla ecological divergence, such as diet, ranging and nesting patterns, and the mating system. Diet is a key component of the species' adaptive complexes that facilitates avoidance of direct competition from the other. While the nutritional basis for chimpanzee food choice remains unclear and no doubt varies from site to site, this species is a ripe fruit specialist and ranges farther during periods of ripe fruit scarcity. Gorillas in the same habitat also feed on ripe fruit when widely available, but fall back onto fibrous plant foods during lean periods. The inclusion of animal protein in the diet of the chimpanzees and its absence in that of the gorillas also distinguish the species ecologically. It may also offer clues to aspects of ecological divergence among early members of the hominid phylogeny. The paper concludes by suggesting likely characteristics of sympatric associations of Pliocene hominids, based on field data from extant sympatric apes.

Diet and seasonal changes in sympatric gorillas and chimpanzees at Kahuzi–Biega National Park

Based on 8 years of observations of a group of western lowland gorillas (Gorilla beringei graueri) and a unit-group of chimpanzees (Pan troglodytes schweinfurthii) living sympatrically in the montane forest at Kahuzi-Biega National Park, we compared their diet and analyzed dietary overlap between them in relation to fruit phenology. Data on fruit consumption were collected mainly from fecal samples, and phenology of preferred ape fruits was estimated by monitoring. Totals of 231 plant foods (116 species) and 137 plant foods (104 species) were recorded for gorillas and chimpanzees, respectively. Among these, 38% of gorilla foods and 64% of chimpanzee foods were eaten by both apes. Fruits accounted for the largest overlap between them (77% for gorillas and 59% for chimpanzees). Gorillas consumed more species of vegetative foods (especially bark) exclusively whereas chimpanzees consumed more species of fruits and animal foods exclusively. Although the number of fruit species available in the montane forest of Kahuzi is much lower than that in lowland forest, the number of fruit species per chimpanzee fecal sample (average 2.7 species) was similar to that for chimpanzees in the lowland habitats. By contrast, the number of fruit species per gorilla fecal sample (average 0.8 species) was much lower than that for gorillas in the lowland habitats. Fruit consumption by both apes tended to increase during the dry season when ripe fruits were more abundant in their habitat. However, the number of fruit species consumed by chimpanzees did not change according to ripe fruit abundance. The species differences in fruit consumption may be attributed to the wide ranging of gorillas and repeated usage of a small range by chimpanzees and/or to avoidance of inter-specific contact by chimpanzees. The different staple foods (leaves and bark for gorillas and fig fruits for chimpanzees) characterize the dietary divergence between them in the montane forest of Kahuzi, where fruit is usually scarce. Gorillas rarely fed on insects, but chimpanzees occasionally fed on bees with honey, which possibly compensate for fruit scarcity. A comparison of dietary overlap between gorillas and chimpanzees across habitats suggests that sympatry may not influence dietary overlap in fruit consumed but may stimulate behavioral divergence to reduce feeding competition between them.

Phenology of figs in Budongo Forest Uganda and its importance for the chimpanzee diet

AbstractThis paper reports on the phenological patterns of figs in Budongo Forest, Uganda, and how it relates to chimpanzee food availability in different seasons. In addition, we analysed the dung of chimpanzees to understand the composition of fruits in their diet. The aim of our study was to assess Ficus phenology and how it affects chimpanzee diet. Fifteen species of figs were monitored for fruit (syconium) and leaf phenology between June 2000 and 2001. Ficus fruit production varied significantly between and within species, and also with tree trunk and crown diameters. Fig fruit production was asynchronous and individual fig trees produced crops from one to five times in a year. In addition to fruits, chimpanzees fed on young leaves of some Ficus species. Shedding of old Ficus leaves coincided with the dry season, followed by appearance of young leaves. The dry season in Budongo is a period of general fruit scarcity. The combination of fig fruits and young leaves make up the most important food in the diet of chimpanzees. From the chimpanzee dung, more than 78% of seeds comprised fig ‘seeds’ (nutlets) and the rest of the diaspores were from other tree species. Our findings suggest that chimpanzees disperse large number of diaspores in their dung, thereby serving as important agents of natural forest regeneration.

Chimpanzee diet and habitat selection in the Budongo Forest Reserve, Uganda

Between June 2000 and August 2001 observations were made on food types, plant species and parts consumed by chimpanzee in relation to various habitats in the Budongo Forest Reserve (BFR), Uganda. Factors influencing their occurrence as well as their activity patterns were also assessed. The chimpanzees of the BFR spent 80% of their daytime feeding and their diet comprised 56 plants species of which 94% were trees. Chimpanzees spent most of their feeding time on B. papyrifera, Ficus sur, Ficus mucuso, Ficus exasperata and Ficus variifolia. Chimpanzees fed mostly on fruits (71%), favouring ripe ones, and young leaves (16%). Factors positively influencing occurrence of chimpanzees included habitat types (logged area and forest edge), plant types (trees), food types (fruits), fruit maturity (ripe fruits), and fruit quantity. Logged area and forest edge provided 76% of the chimpanzee food but are also the habitats with the highest human interference, e.g. logging and agriculture encroachment. Past forest management plans did not consider chimpanzee food trees; most were considered weeds and killed with aboricides. We conclude that the long-term survival of chimpanzees of the BFR requires implementation of management plans based on conservation of food tree species.

The home range of the Sonso community of chimpanzees from the Budongo Forest, Uganda

AbstractEarly studies of chimpanzees in the Budongo Forest, Uganda, reported only rough estimates for home range size. This study aimed to quantify home range size and habitat composition for chimpanzees of the Sonso community in this forest. Home range is the habitually used portion of the total area over which an animal travels, and for chimpanzees the home range is shared by the community. From data collected in 1994 and 1995, the home range for this community was estimated to cover an area of 6.78 km2 using the minimum convex polygon analysis technique and 6.89 km2 using fixed kernel analysis. Habitat was highly heterogeneous. The small home range and consequent high local population density (approximately 6.8 individuals km−1) suggests that the Sonso region is highly productive in chimpanzee foods, possibly in contrast to other parts of the forest. This estimate of home range size is among the smallest reported for habituated chimpanzees, but comparisons with other sites are confounded by methodological and analytical differences. Future studies of chimpanzee ranging patterns should endeavour to use precise locations and the latest analytical techniques to ensure accurate estimation of range size and structure, and intersite comparability.

Important Habitat for Chimpanzees in Mali

Analysis of botanical data is presented from the standpoint of chimpanzee natural history. The Sudano-Guinean gallery forest type dominated by the tree Gilletiodendron glandulosum appears to be important habitat for chimpanzees due to vegetation structure, presence of permanent surface water, and, particularly, abundance of diverse food plants throughout the year. Based on fecal analysis, observation of feeding remains, observation of sympatric primates, ethnographic research, and literature review, sixty probable chimpanzee food plants have been identified in the Gilletiodendron forest of Mali. Phytogeographical analysis indicates that chimpanzees in Mali’s Sudanian climate zone eat mainly Sudano-Guinean plant species. Heavy reliance on Sudano-Guinean vegetation may indicate that modern chimpanzee populations in savanna areas are relicts, and that the species was originally adapted to mesic Guinean forests. There appears to be niche separation based on topography between humans and chimpanzees which breaks down in times of human food shortage, and the potential for competition is high.

The Nuts and Bolts of Captive Chimpanzee Diets and Food as Enrichment: A Survey

Beyond planning for good nutrition, one of the Cornerstones of a successful captive-chimpanzee wellness program is the opportunity for the nonhuman primates to express normal feeding and foraging behaviors. This study presents the results of a survey of 11 institutions—8 zoological and 3 research facilities—given to ascertain how daily diets and feeding enrichments were accomplished. Information represents 806 captive chimpanzees, and entails a composite of captive chimpanzee daily diets, forage and browse materials, periodic treats, medicating and supplemental foods, alternative feeding techniques, and food devices. Results suggest facilities are moving away from timed feeding schedules, which tend to increase prefeeding levels of agonism, to feeding a wide variety of foods throughout the day and using a wide variety of feeding techniques.

Floral Lists from Five Study Sites of Apes in the African Tropical Forests. List of Plant Species Identified in the Northern Part of the Lope Reserve, Gabon.

Research on lowland gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) began at the 'Station d'Etudes des Gorilles et Chimpanzes’ in the Lopé Reserve, central Gabon, in 1983 and is on-going. This paper lists 676 species of plants belonging to 91 families that occur in the 50 sq. km study area. Data on trees with diameters of 10 cm or more were collected systematically along line transects and opportunistic collections of fertile plants were made. For each plant species, the life-form, habitat preference and density (for trees recorded on transects) are listed. For plants that provide food for gorillas and chimpanzees, the part eaten is given. The plant species list is not complete but shows the flora of the SEGC study area to be diverse. The seven habitat types described range from Savanna to Closed Canopy Forest but the study area is dominated by Marantaceae Forest. Gorillas and chimpanzees at Lope have diverse diets and obtain food from plants in all of the habitat types. Some minor (in terms of area) habitats provide large amounts of food in particular seasons. Comparison of ape diets in different parts of Africa can only advance if vegetation inventories for each study site are compiled and published.

Measuring Chimpanzee food Abundance.

The assessment of food abundance is critical to address many theoretical questions concerning chimpanzee ecology and social organization. A variety of methods have been used to estimate habitat-wide food abundance. Since methods vary between sites, it is difficult to make meaningful intersite comparisons, without calibration of the different methods. We compare three methods used to estimate fruit abundance simultaneously in the Kibale Forest Reserve, Uganda. Estimates of fruit abundance derived from fruit traps were not related to estimates derived from either systematic transect sampling or estimates obtained from observing fruiting phenology of key species on a fruit trail. However, estimates based on fruit trail data and transect data were correlated. We also report the results of surveys for herbaceous food availability using data from three different sites, employing similar, but not identical methods. The results of these analyses illustrate the difficulties encountered when data generated by divergent methods are compared, and we present specific recommendations as to how future studies might be structured to facilitate comparability between sites.

Composition of the diet of chimpanzees and comparisons with that of sympatric lowland gorillas in the lopé reserve, gabon.

Over an eight-year period, a total of 174 food items were recorded for chimpanzees (Pan t. troglodytes) in the Lopé Reserve in central Gabon. Plant foods, principally fruit, dominated the diet but insects were eaten regularly, and predation on at least three species of mammal occurred infrequently. The diversity of the vegetative component of the diet (leaves, stems, and bark) was probably underestimated by fecal analysis. Comparison of chimpanzee diet at Lopé with that of sympatric lowland gorillas showed the majority of foods were eaten by both species (73% of chimpanzee food items and 57% of gorilla food items). The overlap of fruit species was greater (82% and 79%, respectively) than that of other food classes. Both chimpanzees and gorillas harvested the majority of their plant foods arboreally (76% and 69%, respectively). The high degree of dietary overlap suggested that ecological competition between these two closely related species might exist. Few overt signs of competition for food either between or within species were observed but when fruit was scarce, the diets of the two species showed greatest divergence. The major differences between chimpanzee and gorilla diet at Lopé were the larger quantities of vegetative foods regularly eaten by gorillas and their ability to resort to a diet dominated by vegetative foods when fruit was scarce. In these respects, chimpanzees at Lopé resembled populations of Pan troglodytes studied elsewhere while Lopé gorillas resembled mountain gorillas (Gorilla g. beringei) and bonobos (Pan paniscus) in their greater dependence on vegetative foods. © 1993 Wiley-Liss, Inc.

Aspilia spp. Leaves: A puzzle in the feeding behavior of wild chimpanzees

Unlike other chimpanzee food items, the leaves ofAspilia pluriseta, A. rudis and A. mossambicensis (Compositae) are eaten without being chewed. Moreover,A. pluriseta andA. rudis are eaten slowly and singly and particularly in the early morning. This unusual behavior suggests thatAspilia leaves offer peculiar stimuli, perhaps with pharmacological effects.