Diet of chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda, 1. Diet composition and diversity

Chimpanzees (Pan troglodytes) are ecologically flexible omnivores with broad diets comprising many plant and animal foods, although they mostly eat fruit (including figs). Like other ecologically flexible nonhuman primates (e.g., baboons, Papio spp.) with broad diets, their diets vary across habitats. Much data on diets come from short studies that may not capture the range of variation, however, and data are scant on variation within habitats and populations. We present data on diet composition and diversity for chimpanzees at Ngogo, in Kibale National Park, Uganda, collected over a 15-year period, with a focus on the plant components of the diet. We compare Ngogo data to those on chimpanzees at the nearby Kibale site of Kanyawara, on other chimpanzee populations, and on some other frugivorous-omnivorous primates. Results support the argument that chimpanzees are ripe fruit specialists: Ngogo chimpanzees ate a broad, mostly fruit-based diet, feeding time devoted to fruit varied positively with fruit availability, and diet diversity varied inversely with fruit availability. Comparison of Ngogo and Kanyawara shows much similarity, but also pronounced within-population dietary variation. Chimpanzees fed much more on leaves, and much less on pith and stems, at Ngogo. Figs accounted for somewhat less feeding time at Ngogo, but those of Ficus mucuso were quantitatively the most important food. This species is essentially absent at Kanayawara; its abundance and high productivity at Ngogo, along with much higher abundance of several other important food species, help explain why chimpanzee community size and population density are over three times higher at Ngogo. High inter-annual variation at Ngogo highlights the value of long-term data for documenting the extent of ecological variation among chimpanzee populations and understanding how such variation might affect population biology and social dynamics.     

Suitable Habitats for Endangered Frugivorous Mammals: Small-Scale Comparison,Regeneration Forest and Chimpanzee Density in Kibale National Park,Uganda

Landscape patterns and chimpanzee (Pan troglodytes schweinfurthii) densities in Kibale National Park show important variation among communities that are geographically close to one another (from 1.5 to 5.1 chimpanzees/km²). Anthropogenic activities inside the park (past logging activities, current encroachment) and outside its limits (food and cash crops) may impact the amount and distribution of food resources for chimpanzees (frugivorous species) and their spatial distribution within the park. Spatial and temporal patterns of fruit availability were recorded over 18 months at Sebitoli (a site of intermediate chimpanzee density and higher anthropic pressure) with the aim of understanding the factors explaining chimpanzee density there, in comparison to results from two other sites, also in Kibale: Kanyawara (low chimpanzee density) and Ngogo (high density, and furthest from Sebitoli). Because of the post-logging regenerating status of the forest in Sebitoli and Kanyawara, smaller basal area (BA) of fruiting trees most widely consumed by the chimpanzees in Kanyawara and Sebitoli was expected compared to Ngogo (not logged commercially). Due to the distance between sites, spatial and temporal fruit abundance in Sebitoli was expected to be more similar to Kanyawara than to Ngogo. While species functional classes consumed by Sebitoli chimpanzees (foods eaten during periods of high or low fruit abundance) differ from the two other sites, Sebitoli is very similar to Kanyawara in terms of land-cover and consumed species. Among feeding trees, Ficus species are particularly important resources for chimpanzees at Sebitoli, where their basal area is higher than at Kanywara or Ngogo. Ficus species provided a relatively consistent supply of food for chimpanzees throughout the year, and we suggest that this could help to explain the unusually high density of chimpanzees in such a disturbed site.     

The significance of fibrous foods for Kibale Forest chimpanzees.

Four categories of plant food dominated the diet of chimpanzees in Kibale Forest, Uganda: non-fig tree fruits, fig tree fruits, herbaceous piths and terrestrial leaves. Fruit abundance varied unpredictably, more among non-figs than figs. Pith intake was correlated negatively with fruit abundance and positively with rainfall, whereas leaf intake was not influenced by fruit abundance. Piths typically have low sugar and protein levels. Compared with fruits and leaves they are consistently high in hemicellulose and cellulose, which are insoluble fibres partly digestible by chimpanzees. Herbaceous piths appear to be a vital resource for African forest apes, offering an alternative energy supply when fruits are scarce.     

Comparative Feeding Ecology of Two Communities of Chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) in Kibale National Park,Uganda

Several recent studies have documented considerable intraspecific and intrapopulation ecological variation in primates. However, we generally lack an understanding of how such variability may be linked to concomitant demographic variation among groups or populations of the same species, particularly in regard to large-bodied and wide-ranging species with high ecological flexibility, such as chimpanzees (Pan troglodytes). We compared the feeding ecology of chimpanzees inhabiting 2 sites in Kibale National Park, Uganda that differ 3-fold in chimpanzee density and support notably different plant communities. Chimpanzees at Ngogo, a site with the largest known chimpanzee community and unusually high chimpanzee density, spent a significantly lower percentage of time resting (and pregnant and lactating females spent more time feeding), incorporated higher percentages of ripe fruit in their diet, had lower dietary diversity values, and had shorter and less variable average patch residency times than did their counterparts at the nearby Kanyawara site, which supports a relatively low density of chimpanzees. In addition, feeding party size was significantly and positively related to feeding patch size at Ngogo, but not at Kanyawara. Together these findings aid in explaining the noted disparity in chimpanzee community size and density between Ngogo and Kanyawara by suggesting that the diet of Ngogo chimpanzees is of higher overall quality than that of Kanyawara chimpanzees. They also highlight the potentially profound influence of even small-scale habitat heterogeneity on the ecology of primates. Researchers must take such influences into account when attempting to draw conclusions about species- or population-level characteristics.     

Influence of fruit availability on macronutrient and energy intake by female chimpanzees

Daily energy intake of adult female mammals is influenced by environmental conditions and physiological requirements, including reproduction. We examined the effects of fruit availability on macronutrient and metabolisable energy (ME) intake by adult female chimpanzees (Pan troglodytes schweinfurthii) of the Kanyawara community in Kibale National Park, Uganda, from January 2014 through June 2015. Drupe fruits were abundant for 4 months, whereas the other 14 months were dominated by fig fruits. The mean daily intake of food (dry matter) and ME did not differ between drupe‐months and fig‐months. However, foraging costs were higher during fig‐months, as indicated by a 20% increase in feeding time. Furthermore, during drupe‐months female chimpanzees ingested more water‐soluble carbohydrates and lipids, and less available protein and neutral detergent fibre. Although ME intake did not differ consistently between drupe‐months and fig‐months, they consumed more on days when ripe fruit dominated the diet than when leaves and pithy stems dominated the diet. Our data suggest that differences in diet quality between drupes and figs can have important effects on frugivore foraging and that they influence net energy gain more by their effects on macronutrient composition or foraging cost than by their direct impact on energy intake.     

Mangabey(Cercocebus albigena). Social organization and population density in relation to food use and availability.

Data are presented on the feeding behavior and activities of mangabeys (Cercocebus albigena) in the Ngogo study area, Kibale Forest, Uganda. Mangabeys spend 47% of activity observations feeding, 27% moving, and the remainder of the activity observations is accounted for by grooming, playing, vocalizing, copulating, etc. Feeding on fruit constitutes 58% of feeding records, arthropods 25%, young leaves and flowers 10%, cambium 5% and rare and unidentified items 2%. 29 tree species are used as sources of vegetable food and 31 tree species are used as substrate for arthropod search. Mangabeys move an average distance of 1,299 m per day, and use an average of 28,50 X 50 m quadrats per day. The activity patterns, the types and number of food species, the daily distances traveled, and the number of quadrats used per day, are not significantly different from those found in the literature for mangabeys in the Kanyawara research area, Kibale Forest, Uganda. Mangabey population density in Ngogo is approximately 1.46 times that of the Kanyawara mangabeys. The difference in density is associated with Ngogo exhibiting a greater mangabey food tree density than is found at Kanyawara. The higher mangabey density in Ngogo is associated with an average group size similar to that at Kanyawara, and an increase in the number of groups per unit area. The greater number of groups is accommodated by the mangabey having smaller home ranges, and less home range overlap than do the Kanyawara mangabeys. I suggest that these results are compatible with an interpretation based on disease control via regulation of group size, and social and spatial isolation between groups. The role of food availability in regulation of group size, or determining land tenure systems remains uncertain.     

Foraging Patterns of Sympatric Hornbills during the Nonbreeding Season in Arunachal Pradesh, Northeast India

The diet and food resource partitioning of three sympatric hornbills (Great Hornbill Buceros bicornis, Wreathed Hornbill Aceros undulatus, and Oriental Pied Hornbill Anthracoceros albirostris) during the nonbreeding season were studied relative to fruit availability in a foothill semievergreen forest of Arunachal Pradesh, northeast India. Hornbills fed on fruits of 49 plant species that comprised over 95 percent of their diet. Hornbill species partitioned food resources by varying the relative contribution of figs and non‐fig fruits in the diet. Similarity in non‐fig fruit diet was low. Ten species contributed to over 90 percent of the non‐fig diet. The availability of non‐fig fruits was much lower in the nonbreeding season than in the breeding season; however, despite lower fruit availability during the nonbreeding season, hornbills had a wide diet breadth and indirect evidence suggests that Wreathed Hornbills foraged widely in this season for fruit. Great Hornbills relied more on figs that were available year‐round. The diverse diet breadth that included rare and patchy fruit resources underscores the importance of conserving large forest tracts for hornbills.     

Diet and reproductive function in wild female chimpanzees (Pan troglodytes schweinfurthii) at Kibale National Park, Uganda

Human female reproductive function is highly sensitive to current energetic condition, indicating adaptation to modulate reproductive effort in accordance with changing ecological conditions that might favor or disfavor the production of offspring. Here, we test the hypothesis that reproductive capacity in female chimpanzees is likewise limited by current energetic condition. We used 12 years of data on wild chimpanzees (Pan troglodytes schweinfurthii) in the Kanyawara community of Kibale National Park, Uganda, to examine the relationship of dietary quality, as assessed by fruit components of the diet, to the occurrence of sexually receptive females, concentrations of ovarian steroid hormones, and timing of conception. We found that the frequency of females having sexual swellings was positively related to the consumption of drupe fruits. Estrogen levels of both cycling and noncycling females increased during seasonal peaks in the consumption of drupe fruits. When average fruit consumption remained high across months, females conceived more quickly. These results support the hypothesis that cycling and conception in chimpanzees are contingent upon high energy balance, and they indicate that the availability of fruit is a key variable limiting reproductive performance in chimpanzees. Chimpanzees appear to share with humans a reproductive system that is primed to respond to proximate levels of energy acquisition.     

Urinary C-peptide tracks seasonal and individual variation in energy balance in wild chimpanzees

C-peptide of insulin presents a promising new tool for behavioral ecologists that allows for regular, non-invasive assessment of energetic condition in wild animals. C-peptide is produced on an equimolar basis with insulin, thus is indicative of the body's response to available glucose and, with repeated measurement, provides a biomarker of energy balance. As yet, few studies have validated the efficacy of C-peptide for monitoring energy balance in wild animals. Here, we assess seasonal and interindividual variation in urinary C-peptide concentrations of East African chimpanzees (Pan troglodytes schweinfurthii). We assayed 519 urine samples from 13 adult male chimpanzees in the Kanyawara community of Kibale National Park, Uganda. C-peptide levels were significantly predicted by the total amount of fruit and the amount of preferred fruit in the diet. However, chimpanzees had very low C-peptide titers during an epidemic of severe respiratory illness, despite highly favorable feeding conditions. Kanyawara males had significantly lower C-peptide levels than males at Ngogo, a nearby chimpanzee community occupying a more productive habitat. Among Kanyawara males, low-ranking males had consistently higher C-peptide levels than dominant males. While counterintuitive, this result supports previous findings of costs associated with dominance in male chimpanzees. Our preliminary investigations demonstrate that C-peptide has wide applications in field research, providing an accessible tool for evaluating seasonal and individual variation in energetic condition, as well as the costs of processes such as immune function and reproduction.     

Infanticide and cannibalism by male chimpanzees at Ngogo, Kibale National Park, Uganda

Researchers have documented infanticide by adult males in four wild chimpanzee populations. Males in three of these have killed infants from outside of their own communities, but most infanticides, including one from Kanyawara, in Kibale National Park, Uganda, took place within communities. Here we report two new cases of infanticide by male chimpanzees at a second Kibale site, Ngogo, where the recently habituated chimpanzee community is the largest yet known. Both infanticides happended during boundary patrols, which occur at a high frequency there. Patrolling males attacked solitary females who were unable to defend their infants successfully. The victims were almost certainly not members of the Ngogo community. Males cannibalized both infants and completely consumed their carcasses. These observations show that infanticide by males is widespread in the Kibale population and that between-community infanticide also happens there. We discuss our observations in the context of the sexual selection hypothesis and other proposed explanations for infanticide by male chimpanzees. The observations support the arguments that infanticide has been an important selective force in chimpanzee social evolution and that females with dependent infants can be at great risk near range boundaries, but why male chimpanzees kill infants is still uncertain.     

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

This 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.     

Floristic heterogeneity at Ngogo,Kibale National Park,Uganda and possible implications for habitat use by chimpanzees (Pan troglodytes)

Tropical forest tree communities exhibit heterogeneity at multiple spatial scales, with important implications for animals relying on these resources. However, different organisms may perceive heterogeneity in the floristic community in very different ways. Here, we characterize the overall extent of heterogeneity in the floristic community at Ngogo, in Kibale National Park, Uganda. Also, using information from studies on the diet of chimpanzees (Pan troglodytes) inhabiting Ngogo, we quantify the extent to which the habitat is likely perceived as heterogeneous by this species. The forest as a whole is slightly more diverse than comparable sites in the Congo Basin, but this diversity is driven by a relatively high proportion of rare species represented by few individuals. From the perspective of chimpanzees, the forest is, unsurprisingly, even more heterogeneous. Species that provide fruit for chimpanzees during times of low overall fruit abundance and that display interindividual synchrony in fruiting were the most common chimpanzee resource in our sample, whereas species that provide fruit during times of low overall fruit abundance and that display asynchronous fruiting were the least common. We discuss the implications of the differences in density and distribution of various classes of resources for chimpanzee habitat use and foraging efficiency.     

Fruit availability and chimpanzee party size at Kahuzi montane forest,Democratic Republic of Congo

The effect of fruit availability on chimpanzee party size was investigated in the montane forest of Kahuzi. Seasonal variation in both fruit availability and party size was examined. Fruit abundance per se does not affect chimpanzee party size. However, seasonality and distribution patterns of fruits are both determinant ecological factors that control the size of chimpanzee parties at Kahuzi. There was no correlation between fruit abundance and the spatial distribution of fruits. When fruits were clumped and available in large amounts for a long period, chimpanzee party size increased, or otherwise decreased when fruits were highly available for only a limited period. Tree species that produced only a small amount of ripe fruit throughout the year did not affect the foraging party size of chimpanzees. Temporal and spatial variability in fruit abundance seems to constrain grouping patterns of chimpanzees at Kahuzi more so than in other chimpanzee habitats previously described.     

Dietary specialization and fruit availability among frugivorous birds on Sulawesi

Over 20 months I collected data on the diet composition and fruit availability for 23 frugivorous bird species (pigeons, parrots, hornbills and passerines) in two lowland rain forests on Sulawesi, Indonesia. Using these data I determined species dependency on fruit, diet composition, diet breadth and the availability of their fruit resources. Fruit dependency ranged from 44 to 100% of diets across the assemblage, with significant inter-order differences reflecting shared evolutionary history within orders. By contrast, diet breadths did not differ between bird orders owing to high within-order variability, possibly as a result of species-specific foraging strategies. Overall, no significant relationship existed between fruit dependency and diet breadth, which indicated that they are not interchangeable measures of dietary specialization, but that each provided important information on dietary specialization, and enabled assessment of resource requirements and availability. The assemblage consumed the fruits of 120 species representing 40 plant families. Figs ( Ficus spp.) were of great importance across the assemblage and comprised 57% of all fruit-eating records. For hornbills, passerines and pigeons, figs accounted for substantial proportions of monthly feeding records (= 58%) and were consumed whatever the availability of other fruits. Figs were therefore a fundamental part of species' diets, possibly every month, and not merely important during times of relative scarcity of other fruit. Conservation of fig trees both inside and outside protected areas is likely to be important in maintaining healthy populations of figs and the frugivorous birds that depend on them.     

The fruit phenology of Musanga leo-errerae and its importance for chimpanzee diet in Kalinzu Forest Uganda

This study reports the rate of fruit phenological pattern of Musanga leo-errerae and how it sustains the chimpanzee population better than other fruits in Kalinzu Forest Reserve. We analysed 2635 faecal samples to determine the proportion of M. leo-errerae by composition of fruit diet compared with other fruits eaten by chimpanzees. Musanga leo-errerae trees were monitored for fruit production between November 2002 and December 2004. Musanga leo-errerae fruit production did not vary significantly between months (ANOVA, F  = 2.0, d.f. = 11, P  = 0.13). The size of fruit and rate maturation varied with seasons, although fruit production was synchronous and available all year round. From the 2635 faecal samples analysed, 79.2% contained M. leo-errerae fruit seed. Chimpanzee diet in Kalinzu is 75% frugivorous, 37.2% of which is solely contributed by M. leo-errerae fruit. The continuous availability of M. leo-errerae fruit makes it the most important food for chimpanzees in this forest, especially during general fruit scarcity there by joining figs in importance for chimpanzee survival in tropical Africa.     

Ecological constraints on the grouping of wild orang-utans (Pongo pygmaeus) in the Gunung Leuser National Park,Sumatra, Indonesia

The orang-utan (Pongo pygmaeus)is an interesting subject on which to base an evaluation of the costs and benefits of social life in apes, since grouping in this heavy, arboreal frugivore is facultative. In the Ketambe area of Sumatra, Indonesia, the food sources of wild orang-utans display a clear seasonality. The two main food types— figs and other, nonfig, fruits— fulfill different functions. The huge fig trees meet the high caloric requirements of the ape and are therefore visited regularly throughout the year. Nonfig fruits are an additional food source but become a really important alternative when figs are in short supply. Since fig trees are relatively rare, it is only in the nonfig fruiting season that food is relatively abundant. Two types of orang-utan groupings could be distinguished. During lean periods, groups formed in the few productive fig trees available can be explained as forced aggregations taking place in spite of centrifugal forces caused by competition. Only when a temporary surfeit of food slackens these centrifugal forces (i.e., during the fruit season) does the tendency to form spontaneous social groups (the second type of grouping) reveal itself. It is suggested that the development of social skills is an important aspect of grouping in adolescent orang-utans. For the adult male, safeguarding his reproductive success by protecting females against sexually aggressive subadult males is probably the only reason for being in groups.     

Diet and Feeding Ecology of Chimpanzees (Pan troglodytes) in Bulindi, Uganda: Foraging Strategies at the Forest–Farm Interface

Wild animals increasingly inhabit human-influenced environments such as forest fragments amid agricultural systems. Dietary studies provide a means of assessing wildlife responses to anthropogenic habitat changes. Chimpanzees are specialist frugivores that consume other plant parts, e.g., fibrous pith and leaves, in greater amounts during fruit shortages. I examined the plant diet and seasonal foraging strategies of chimpanzees inhabiting small forest fragments within a cultivated landscape in Uganda. I determined diet over 13 mo via systematic fecal analysis, supplemented by direct observation and feeding trace evidence. I identified important foods and examined their role as seasonal fallbacks. Diet composition and breadth were overall species typical. Chimpanzees were highly frugivorous and the fruit component of fecal samples exceeded that of nonfruit fiber in all months. Forest fruit availability fluctuated seasonally, including a 3-mo low fruiting season, when overall fruit intake declined. During this time chimpanzees pursued a mixed strategy of increasing fiber consumption and feeding more heavily on energy-rich cultivars, including those obtained through crop raiding. The data suggest that exploiting agricultural fruits helped chimpanzees maintain a fruit-dominated diet when forest fruit was scarce. No evidence suggested this disturbed forest–farm mosaic is a food-impoverished habitat for chimpanzees overall. Nevertheless, cultivar feeding creates conflict with people and the high nutritional quality of crops is likely offset by the inherent risk associated with obtaining them. This study adds to growing evidence of ecological and behavioral adaptability of Pan troglodytes in response to anthropogenic habitat alteration. Targeted conservation of key natural foods for wildlife —particularly fallbacks— would help reduce conflicts and improve the survival prospects of threatened species sharing environments with people.     

Diet in one group of woolly spider monkeys,or muriquis (Brachyteles arachnoides)

Data on feeding behavior in one group of muriquis (Brachyteles arachnoides) were collected during a 14 month study at Fazenda Montes Claros, Minas Gerais, Brazil. Muriquis devoted an average of 51% of their annual feeding time to leaves, 32% to fruits, and 11% to flowers. The high proportion of leaves in their diet is consistent with predictions from the energetics of body size. However, they devoted a greater proportion of their feeding time to patchy fruit and flower resources than was expected from comparisons with smaller, sympatric howler monkeys. Muriqui diet varied with the availability of preferred food types across sample months. Fruit and flower consumption corresponded to the availability and abundance of these food resources in the forest. Leaves contributed substantially to muriqui diet throughout the year but appeared to be eaten primarily to provide necessary protein and/or necessary bulk. Male and female diets differed only in the greater proportion of feeding time females devoted to flowers.     

Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park,Rwanda

Almost all primates experience seasonal fluctuations in the availability of key food sources. However, the degree to which this fluctuation impacts foraging behavior varies considerably. Eastern chimpanzees (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda, live in a montane forest environment characterized by lower primary productivity and resource diversity than low‐elevation forests. Little is known about chimpanzee feeding ecology in montane forests, and research to date predominantly relies on indirect methods such as fecal analyses. This study is the first to use mostly observational data to examine how seasonal food availability impacts the feeding ecology of montane forest chimpanzees. We examine seasonal changes in chimpanzee diet and fallback foods (FBFs) using instantaneous scan samples and fecal analyses, supported by inspection of feeding remains. Chimpanzee fruit abundance peaked during the major dry season, with a consequent change in chimpanzee diet reflecting the abundance and diversity of key fruit species. Terrestrial herbaceous vegetation was consumed throughout the year and is defined as a “filler” FBF. In contrast to studies conducted in lower‐elevation chimpanzee sites, figs (especially Ficus lutea) were preferred resources, flowers were consumed at seasonally high rates and the proportion of non‐fig fruits in the diet were relatively low in the current study. These divergences likely result from the comparatively low environmental diversity and productivity in higher‐elevation environments.     

Behavioral Ecology of Sympatric Chimpanzees and Gorillas in Bwindi Impenetrable National Park,Uganda: Diet

Via a field study of chimpanzees (Pan troglodytes schweinfurthii) and gorillas (Gorilla gorilla beringei) in Bwindi Impenetrable National Park, Uganda, we found that their diets are seasonally similar, but diverge during lean seasons. Bwindi chimpanzees fed heavily on fruits of Ficus sp., which were largely ignored by the gorillas. Bwindi gorilla diet was overall more folivorous than chimpanzee diet, but was markedly more frugivorous than that of gorillas in the nearby Virunga Volcanoes. During 4 mo of the year Bwindi gorilla diet included more food species than that of the chimpanzees. Three factors in particular—seasonal consumption of fibrous foods by gorillas, interspecific differences in preferred fruit species, and meat consumption by chimpanzees—contributed to dietary divergence between the two species. When feeding on fruits, gorillas ate Myrianthus holstii more frequently than chimpanzees did, while chimpanzees included more figs in their annual diet. Chimpanzee diet included meat of duikers and monkeys; gorilla frequently consumed decaying wood.