Food Choice of White-Headed Langurs in Fusui,China

We studied the feeding ecology of white-headed langurs (Trachypithecus leucocephalus) from September 1997 to September 1998 in Fusui Rare and Precious Animal Reserve, SW Guangxi, China. We collected data in the central part of a group of limestone hills where the main population pool of langurs was located. The langurs fed on 50 plant species (belonging to 42 genera from 28 families) out of 164 species in the habitat (belonging to 112 genera from 48 families). Most of the food plant species were not common in the habitat. There are 16 important food species, including 6 key species. White-headed langurs were extremely folivorous, feeding mainly on young leaves (75% of total feeding records) of a broad range of less common plant species, which were in less disturbed areas. Thus, langur groups in high quality habitat had greater access to preferred foods, and the future of langurs in the Reserve may depend on immediate cessation of tree felling.     

The diet of the capped langur (Presbytis pileata) in a moist deciduous forest in Bangladesh

Capped langurs (Presbytis pileata) in Madhupur National Park in north-central Bangladesh have an annual diet that is comprised largely of mature leaves (42% of 20,460 total feeding records). Among colobine monkeys, only some populations of red colobus (Procolobus badius) have a diet richer in mature leaves. New leaves (11%) and fruit (24%) are the other annually important dietary items. Seasonal breakdown of this diet, however, revealed that during the monsoon months of May through September theP. pileata diet is approximately 50% fruit, including pulpy ripe fruit. This is also the period of maximum fruit availability. Data on diet and food availability indicate that while capped langurs subsist on mature leaves during the dry season (80% of diet from November to March), they select fruit and new leaves and switch to these foods whenever they are available. These data support the hypothesis that the colobine feeding strategy is adapted to cope with seasonal food scarcity.     

Resource use by howler monkeys (Alouatta palliata) in the rain forest of Los Tuxtlas,Veracruz, Mexico

The feeding preferences of howler monkeys at their northernmost distribution in the Neotropics are reported for an annual cycle. A remarkable selectivity for 27 species representing 15 families was observed. The Moraceae and Lauraceae plant families were the most important in the diet. The howlers spent an almost equal proportion of their feeding time eating leaves and fruit, and displayed a marked preference for young leaves and mature fruit. The consumption of different plant parts was markedly seasonal and the howlers’ ranging behavior was closely associated with the availability of young leaves and mature fruit. Their home range was unusually large (ca. 60 ha) for howlers and the food species exploited occur at very low densities (93%, ≤ 4 ind/ha). They chose food items richer in protein and energy. Alkaloid compounds, present in some of the leaves, play a secondary role in their dietary selectivity.     

Seasonal variation of diet and food availability in a group of Sichuan snub-nosed monkeys in Shennongjia Nature Reserve, China

We studied the diet and food availability of a group of Sichuan snub-nosed monkeys for 14 months (July 2003 to September 2004, except for February) in the Shennongjia Nature Reserve, China. This species is primarily a lichen eater, with lichens (Usneaceae) accounting for 43.28% of feeding records (n=3,452). Other food types in the diet were young leaves (28.71%), fruits or seeds (14.57%), buds (5.36%), mature leaves (3.51%), herbs (2.09%), bark (1.36%), and flowers (1.13%). The monkeys used 23 plant species. Their diet showed a complicated seasonal variation: the monthly diet varied from primarily lichens in November-April, to a mixture of leaves and lichens in May-July, to a mixture of fruits or seeds and lichens in August-October (the latter depended on annual fruit and seed availability). The proportion of fruits or seeds in the diet was negatively correlated with that of lichens, which suggests that the monkeys prefer fruits or seeds to lichens when all of these items are available. The fruit or seed availability varied greatly between the two study years. The proportion of lichens, young leaves, flowers, and fruits or seeds in the diet was positively associated with their availability. The monkeys appeared to be selective feeders. They preferred 10 tree species for plant parts, and nine tree species for lichens. The selection index of tree species for lichens was positively related to lichen coverage per branch on tree species, demonstrating that the monkeys preferred tree species with abundant lichens, as well as dead trees for lichens. The results suggest that dead-tree harvesting in the reserve could significantly reduce the quality of habitat for these monkeys, and should therefore be prohibited. Connus controversa, Cerasus discadenia, Salix willichiana, and Malus halliana should be conserved as top priority species because the monkeys preferred them for both their vegetative parts and the lichens that grow on them.     

Diet and Food Choice of Trachypithecus francoisi in the Nonggang Nature Reserve, China

We studied the diet and food choice of 1 group of Fran?ois’ langurs (Trachypithecus francoisi) from August 2003 to July 2004 in the Nonggang Nature Reserve, Guangxi province, China. The langurs consumed 90 plant species, including 14 unidentified species. Leaves constituted 52.8% of the diet (38.9% young leaves and 13.9% mature leaves). Fruits and seeds accounted for 17.2% and 14.2%, respectively. Flowers and other items—including petioles, stems, roots, and bark—contributed to 7.5% and 7.4% of the diet, respectively. The langur diet varied according to season. They fed on more young leaves from April to September. Consumption of seeds, petioles, and stems increased between October and March, when young leaves were scarce. The diet shift corresponded to higher dietary diversity during the young leaf-lean period. Though the langurs fed on many plant species, 10 species accounted for 62.2% of the diet, only 2 of which were among the 10 most common tree species in vegetation quadrants, and the percentage of feeding records on a plant species and the percentage of individuals of the species in vegetation quadrants does not correlate significantly. Fran?ois’ langurs fed selectively, and they did not base their diet simply on the abundance of plant species in the habitat.     

Diet ofColobus polykomos on Tiwai Island: Selection of food in relation to its seasonal abundance and nutritional quality

A group of Colobus polykomosat Tiwai, Sierra Leone, demonstrated seasonal flexibility in its diet, with seeds, young leaves, and mature leaves each dominating the diet at different times. Comparison of food consumption with phenological data indicates that seeds are eaten whenever available and are preferred to other foods, while young leaves are preferred to mature leaves. Colobus polykomosalso prefer liane to tree leaves, despite the relatively high quality of mature tree foliage at the Tiwai site. Analysis of protein, fiber, and energy values of foods selected and items available, but not eaten, suggests that preference is related to protein and energy maximization. Leguminous plants, especially Papilionaceae and Mimosaceae, are highlighted as important food sources for C. polykomos;seeds and leaves from these families have a high nitrogen content, and the protein content of leguminous seeds often equals or exceeds that found in leaves. It is predicted, therefore, that colobines living in habitats with a high density of legumes will feed heavily on seeds, subject to constraints such as seasonal availability. Where suitable leguminous species are less common, a mixture of fruits, seeds, and young or mature leaves or both is likely to be selected. The results of this and other recent studies of colobines do not support the notion that colobines are specialist folivores.     

Himalayan <Emphasis Type="Italic">Semnopithecus entellus</Emphasis> at Langtang National Park,Nepal: Diet,Activity Patterns,and Resources

Though researchers have studied lowland gray langurs extensively, there is little information about the Himalayan populations. We provide foraging data from a field study of Himalayan langurs in Langtang National Park, Nepal at 3000–4000 m elevation. Phenological records show marked seasonality in resource abundance, with extremely low availability in winter, increasing abundance in spring and monsoon, and a reduction in fall. Activity budgets indicated greater time devoted to feeding as total vegetation abundance decreased. Diet included leaf buds, ripe fruit, and evergreen mature leaves in winter; deciduous young leaves in spring; and deciduous mature leaves in the monsoon and fall. Supplemental resources, such as underground storage organs, bark, and herbaceous vegetation, were also seasonally important. Among plant part classes included in the phenological sample, abundance and consumption correlate positively for all primary food resources except evergreen mature leaves and unripe fruit. Daily path lengths varied by season and, when controlled for overall vegetation abundance, positively relate to the consumption of soft underground storage organs, fruits, and deciduous mature leaves. The results contradict the common generalization of leaves as ubiquitous or nonpatchy resources.     

Dietary generalists and nutritional specialists: Feeding strategies of adult female blue monkeys (Cercopithecus mitis) in the Kakamega Forest,Kenya

Generalist primates eat many food types and shift their diet with changes in food availability. Variation in foods eaten may not, however, match variation in nutrient intake. We examined dietary variation in a generalist‐feeder, the blue monkey (Cercopithecus mitis), to see how dietary food intake related to variation in available food and nutrient intake. We used 371 all‐day focal follows from 24 adult females (three groups) in a wild rainforest population to quantify daily diet over 9 months. We measured food availability using vegetation surveys and phenology monitoring. We analyzed >700 food and fecal samples for macronutrient content. Subjects included 445 food items (species‐specific plant parts and insect morphotypes) in their diet. Variation in fruit consumption (percentage of diet and total kcal) tracked variation in availability, suggesting fruit was a preferred food type. Fruits also constituted the majority of the diet (by calories) and some fruit species were eaten more than expected based on relative availability. In contrast, few species of young leaves were eaten more than expected. Also, subjects ate fewer young leaves (based on calories consumed) when fruit or young leaves were more available, suggesting that young leaves served as fallback foods. Despite the broad range of foods in the diet, group differences in fiber digestibility, and variation that reflected food availability, subjects and groups converged on similar nutrient intakes (grand mean ± SD: 637.1 ± 104.7 kcal overall energy intake, 293.3 ± 46.9 kcal nonstructural carbohydrate, 147.8 ± 72.4 kcal lipid, 107.8 ± 12.9 kcal available protein, and 88.1 ± 17.5 kcal structural carbohydrate; N = 24 subjects). Thus, blue monkeys appear to be food composition generalists and nutrient intake specialists, using flexible feeding strategies to regulate nutrient intake. Findings highlight the importance of simultaneously examining dietary composition at both levels of foods and nutrients to understand primate feeding ecology.     

Interannual variation in food choice of white‐headed langur inhabiting limestone forests in Fusui,southwest Guangxi,China

Food habits are important factors in the adaptation of wild nonhuman primates. White‐headed langurs (Trachypithecus leucocephalus) are endemic to heavily fragmented limestone forests and adapt to unique living environments via flexible food selection strategies. In this study, we compared the dietary data for white‐headed langurs living in Chongzuo White‐headed Langur National Nature Reserve in 2013 and 2016 to evaluate interannual variations in diet. Our results indicated that young leaves were the main food source for langurs, accounting for 52.4% (SD 25.4%) and 65.2% (SD 22.4%) of their diet in 2013 and 2016, respectively. The pattern of plant part consumption was similar between the two years. The consumption of young leaves varied with the availability of young leaves, whereas the consumption of mature leaves was negatively correlated with young leaf availability. The consumption of plant species and diet diversity were higher in 2013 than in 2016. In both 2013 and 2016, although diet diversity varied with the consumption of mature leaves, it was negatively correlated with the consumption and availability of young leaves. Dietary interannual variation is likely to either be linked to phenological variations or indicate that white‐headed langurs have a flexible ecological adaptation coping with habitat fragmentation.     

Diet selection in the green ringtail possum (Pseudochirops archeri): A specialist folivore in a diverse forest

Abstract This study investigated the feeding ecology of the green ringtail possum, Pseudochirops archeri (Pseudocheiridae) in a tropical rainforest with 94 plant species in the canopy. Over 50% of tree use was from only four tree species, Aleurites rockinghamensis, Ficus fraseri, Arytera divaricata and Ficus copiosa. These species were used significantly more frequently than would be expected if tree species were selected randomly in proportion to their relative abundance in the forest. Conversely, 88 other tree species present were used less frequently than expected. Possums also favoured particular individual trees within some of the preferred tree species. In 91% of feeding observations, possums consumed mature leaves only. The availability of young leaves, flowers and fruit varied throughout the year, with a peak in availability of these resources during the early wet season. By primarily selecting mature leaves, green ringtail possums reduce their dependence on seasonally variable resources. We suggest that green ringtail possums should be considered as specialist folivores, focusing on only a few of the tree species available, possibly due to advantages associated with limiting the number of plant secondary metabolites in their diet. Furthermore, they favour certain individual trees within species, perhaps due to intraspecific variation in plant secondary metabolites or nutrient content, behaviour that has been well established in eucalypt folivores. We conclude that green ringtail possums are highly specialized in their feeding ecology, limiting their diet to a small number of continuously available food items.     

Factors Influencing Interannual and Intersite Variability in the Diet of <Emphasis Type="Italic">Trachypithecus francoisi</Emphasis>

Comparative studies of the diet of the same species in different habitats, and over the long term, are essential to understanding a species’ behavioral and ecological plasticity. Moreover, such studies can help researchers and managers evaluate a species’ capacity to cope with changes in habitat quality resulting from natural processes or human disturbance, which is important for developing conservation strategies. We compared dietary data for François’ langur (Trachypithecus francoisi) collected at Nonggang and Fusui Nature Reserves, Guangxi Province, China, over 2 separate study periods to evaluate interannual and intersite variation in diet. Young leaves were the preferred staple foods for langurs, whereas mature leaves and seeds served as fallback foods in response to seasonal shortage in the abundance of young leaves. Species composition of the diets and the percentage of feeding records for plant species varied between the 2 study periods. The langurs at both study sites fed selectively, and they did not base their diet simply on the abundance of plant species in the habitat. However, the plant species eaten by langur groups inhabiting the 2 different reserves were markedly different, and the top 10 food species eaten by the Fusui group showed no overlap with those eaten by the Nonggang group. The variation may be related to differences in forest composition resulting from different level of human disturbance. In summary, our results indicate that François’ langurs exhibit a comparable dietary pattern both temporally and geographically, but there is marked interannual and intersite difference in species composition of the langur diet.     

Selectivity and Variability in the Diet of Milne-Edwards' Sifakas (Propithecus diadema edwardsi): Implications for Folivory and Seed-Eating

Propithecus diadema edwardsi combines a strategy of high selectivity for many food items with the use of more readily available and abundant foods. Selectivity is seen in relation to taxonomic affiliations of plants eaten, forest composition, and phenological patterns. Feeding time is concentrated on relatively uncommon species as indicated by high selection ratios. Annual and monthly dietary diversity is low, with food choices restricted to a relatively narrow set of species: a total of 82 and 73 plant species were eaten by the two groups of which, only 22 and 16% contributed >1% feeding time, however, these values fall with commonly reported ranges. Plant parts eaten varied widely from month to month, with overall variance in seed-eating higher than variance in young or mature leaf feeding. No correlation between percentage feeding time and food availability is significant; instead, monthly feeding patterns are better explained by the availability of particular plant species, which also supports a view of high selectivity in food choice. In contrast to selectivity for many seed, whole fruit, and new leaf sources, reliably abundant food sources appear to be leaves from lianas, epiphytes, and parasites, which were eaten in all focal months. While dramatic interannual differences in dietary composition in response to the absence of a preferred seed source highlight the interpretation of folivores as surviving food crunches by turning to readily available, poor quality resources, this strategy is not unique to folivores.     

Seasonal Energetic Stress in a Tropical Forest Primate: Proximate Causes and Evolutionary Implications

Animals facing seasonal variation in food availability experience selective pressures that favor behavioral adjustments such as migration, changes in activity, or shifts in diet. Eclectic omnivores such as many primates can process low-quality fallback food when preferred food is unavailable. Such dietary flexibility, however, may be insufficient to eliminate constraints on reproduction even for species that live in relatively permissive environments, such as moist tropical forests. Focusing on a forest-dwelling primate with a flexible diet (Cercopithecus mitis) we investigated whether females experience seasonal energetic stress and how it may relate to reproductive seasonality. We used fecal glucocorticoids (fGCs) as an indicator of energetic stress, controlling for the potentially confounding effects of social interactions and reproductive state. We modeled within-female fGC variation with General Linear Mixed Models, evaluating changes in feeding behavior and food availability as main effects. Regardless of reproductive state, fGCs increased when females shifted their diet towards fallback foods (mature leaves and other non-preferred items) and when they spent more time feeding, while fGCs decreased with feeding time on preferred items (insects, fruits, young leaves) and with the availability of young leaves. Changes in fruit availability had no general effects on fGCs, likely because fruits were sought out regardless of availability. As predicted, females in the energetically demanding stages of late pregnancy and early lactation showed greater increases in fGCs between periods of low versus high availability of fruits and young leaves than females in other reproductive states. Potential social stressors had no measurable effects on fGCs. Preliminary evidence suggests that seasonal energetic stress may affect the timing of infant independence from mothers and contribute to unusually long inter-birth intervals compared to closely related species of similar body size. Our findings highlight how the study of stress responses can provide insights into the proximate control of reproductive strategies.     

Diet of <Emphasis Type="Italic">Pygathrix nigripes</Emphasis> in Southern Vietnam

Black-shanked douc langurs (Pygathrix nigripes) are Southeast Asian colobines about which primatologists know very little, but they are classed as endangered because of population decline due to habitat loss. Two preliminary studies have shown that this monkey is primarily folivorous, but there are few details of plant selection or seasonal changes in diet. We set out to observe douc langurs directly in the wild to quantify the diet during wet and dry seasons. We confirmed that the species relies on foliage throughout the year, but it includes significant proportions of fruit and flowers in its diet when those items are available. The douc langurs selected various parts from 152 species of plants in 2 national parks, but there did not appear to be favorite species that were heavily selected over others. In both the wet and dry seasons, the black-shanked douc langurs ate mostly leaves, but the diversity of plants consumed increased and the proportion of fruit eaten almost doubled in the wet season. There were diurnal shifts in food selection, but we found no evidence that the douc langurs were foraging strategically to maximize their protein or energy intake.     

The diet and feeding behavior of the silver leaf monkey (Trachypithecus auratus sondaicus) in Indonesia

I describe the diet and feeding behavior of silver leaf monkeys (Trachypithecus auratus sondaicus) in the Pangandaran Nature Reserve, West Java, Indonesia, and compare a group living in old secondary rain forest with a group living in mixed plantation/secondary forest to determine intraspecific variation in feeding behavior and the importance of the plantation species in the diet of the monkeys. Young leaves and leaf buds made up slightly less than half of their diets, with both groups showing a preference for a few species when seasonally available. Fruits and flowers of a few species were also preferentially selected when available. These included sweet, fleshy fruits, which most other colobines tend to avoid. Young leaf intake was greatest in months when fruit intake was low. Mature leaves were rarely eaten. Both groups spent approximately 20% of feeding time foraging on Moraceae species. Differences in the diet of the two groups were related largely to differences in vegetational composition and the availability and abundance of food items for the species common to both sites. Teak (Tectona grandis) was the top food species of the group living in mixed plantation/secondary forest, with the midribs of young leaves preferentially selected. Young leaves ofT. grandis, available throughout the study, provided a staple food and were eaten when preferred foods were scarce. More favored food items were available to the group living in old secondary forest, though none was a staple food.     

Dietary Variability of Mountain Gorillas in Bwindi Impenetrable National Park,Uganda

Data on intraspecific dietary variability has important implications for understanding flexibility in foraging behavior, habitat utilization, population dynamics, and social behavior and may also assist in conservation efforts. We compared food availability and diet of a group of mountain gorillas (Gorilla beringei beringei) at a high altitude site and 2 groups at a low altitude site in Bwindi Impenetrable National Park, Uganda, from September 2001 to August 2002. Plant species diversity was greater at the low altitude site than at the high altitude site. The two groups at the low elevation consumed more plant species (140 species vs. 62 species), and a greater number of fruit species per mo (7 vs. 3 species) and per yr (36 vs. 11 species) than the high altitude group did. Furthermore, each group shared <51% of important fibrous food items in their diet with the 2 other groups. There is no significant difference in the proportion of days fruit remains were found in the dung among groups. Finally, according to Ivlev's electivity index, all groups positively selected the majority of food items in their diets. We attribute a large proportion of dietary variation between locations to differences in fruit availability and plant species composition between sites. Differences between groups at the low altitude site may be due to variation in food profitability—more profitable foods available to choose in the same area—within their overlapping home range, or group traditions. A comparison of our results with the diets of gorillas of the Virunga Volcanoes in Rwanda and Kahuzi-Biega, DRC shows that eastern gorilla populations have highly variable dietary patterns with limited overlap in species consumed among groups and populations.     

Nutritional composition of the diet of the northern yellow-cheeked crested gibbon (<Emphasis Type="Italic">Nomascus annamensis</Emphasis>) in northeastern Cambodia

This study measured the nutritional composition of foods consumed by the northern yellow-cheeked crested gibbon (Nomascus annamensis) in northeastern Cambodia. One group of N. annamensis was studied, and focal animal sampling was used to observe their feeding behavior. The study was conducted for 4 months (January–April 2015) in the dry season and 69 foods were collected for nutritional analyses. N. annamensis fed on 37 plant species, but only seven species made up more than 80% of feeding time. N. annamensis spent the majority of their time feeding on fruit (60.36%), followed by young leaves (22.60%), flowers (13.74%), and mature leaves (3.30%). Fruit had the highest concentrations of total non-structural carbohydrates, while young leaves had the highest concentration of crude protein compared to other food items. All food items had similar concentrations of lipids, except young leaves, which had lower levels than fruit and flowers. All plant parts consumed by N. annamensis had similar amounts of neutral detergent fiber, acid detergent fiber, and acid detergent lignin. Thirty-two percent of all food items contained condensed tannins, and they had a similar level of it. All foods also had similar energy contents. This study adds to our knowledge of the feeding ecology of N. annamensis by providing baseline data on the make-up of the foods they eat and may contribute to captive feeding programs, ultimately assisting the conservation of this species.     

Dietary breadth and resource use of François' langur in a seasonal and disturbed habitat

Previous studies of Trachypithecus species indicated that they were selective feeders that concentrated on relatively few food species/items. From January to December 2005, I quantified potential food availability and the food species/items eaten by five groups of François' langur (Trachypithecus francoisi) in the Mayanghe Nature Reserve (MNR), People's Republic of China. These langurs fed on 164 species, of which the top ten accounted for 51% of all feeding records. Langurs consumed more species (91) in the spring than in other seasons (73 summer, 75 autumn, and 67 winter), and only 38 species were consumed in all seasons. Nontree food species, such as bushes and lianas, accounted for 47% of the total feeding records and for a majority (68%) of the feeding records in winter. The annual diet consisted of leaves (64% of feeding records), fruit and seed (32%), and other nonfoliage items (4%); the langurs switched from being more folivorous in spring (93%) and summer (79%) to being more frugivorous in autumn (53%) and winter (56%). There was no correlation between the proportion of feeding records and the food availability in the most frequently consumed species, indicating that these langurs were selective feeders; there were significant correlations between consumption and abundance in both the entire set of 112 food species and the set of 86 infrequently consumed species, indicating that foods that are more available are eaten more frequently. It appeared that in the seasonal and disturbed habitat, feeding decisions and diet composition of the langur may be driven more by food availability, and less by animal's selectivity, than at other sites. The results indicate that François' langur copes with habitat alterations by broaden its dietary breadth; this has implications for the adaptive significance of dietary breadth, and has implications for future conservation strategies for species which exist in degraded habitats. Am. J. Primatol. 73:1176–1187, 2011. © 2011 Wiley Periodicals, Inc.     

Microhabitat Variation and Its Effects on Dietary Composition and Intragroup Feeding Interactions Between Adult Female <Emphasis Type="Italic">Lemur catta</Emphasis> During the Dry Season at Beza Mahafaly Special Reserve,Southwestern Madagascar

We compared diets and female feeding agonism in 2 groups of ring-tailed lemurs living in markedly diverse microhabitats in and near the Beza Mahafaly Reserve, Madagascar during mid-to-late gestation periods and height of the dry season to test predictions concerning differences in resource availability, preferred foods, female rank, and degree and frequency of feeding agonism in relation to usurpability and monopolization of food resources. Quadrat sampling in disturbed forest habitat revealed a greater number of plant species than in the gallery forest home range area, but females in both groups consumed nearly equal numbers of actual food plant species. Higher-ranking females in disturbed forest consumed human food scraps from the researchers camp significantly more often than low-ranking females did, while there was no rank effect for consumption of any food type between females in the gallery forest group. Higher rates of female feeding agonism in both groups occurred around usurpable fruit and leaves, as well as over monopolizable human food scraps in the disturbed forest group. There is no association between degree of agonism and food type in either group, and rate of feeding agonism is similar for both groups. The most highly contested food items came in large packages and were high in nutrients: beneficial foods for gestating females in the height of dry season in southwestern Madagascar.     

Food preferences of wild mountain gorillas

Determining the nutritional and phenolic basis of food preference is important for understanding the nutritional requirements of animals. Preference is a measure of which foods would be consumed by an animal if there was no variation in availability among food items. From September 2004 to August 2005, we measured the food preferences of four wild mountain gorilla groups that consume foliage and fruit in Bwindi Impenetrable National Park, Uganda, to determine what nutrients and phenols are preferred and/or avoided. To do so, we asked the following questions: (1) Which plant species do the gorillas prefer? (2) Considering the different plant parts consumed of these preferred species, what nutrients and/or phenols characterize them? (3) Do the nutritional and phenolic characteristics of preferred foods differ among gorilla groups? We found that although some species were preferred and others were not, of those species found in common among the different group home ranges, the same ones were generally preferred by all groups. Second, all groups preferred leaves with relatively high protein content and relatively low fiber content. Third, three out of four groups preferred leaves with relatively high sugar amounts. Fourth, all groups preferred pith with relatively high sugar content. Finally, of the two groups tested, we found that the preferred fruits of one group had relatively high condensed tannin and fiber/sugar contents, whereas the other group's preferred fruits were not characterized by any particular nutrient/phenol. Overall, there were no differences among gorilla groups in nutritional and phenolic preferences. Our results indicate that protein and sugar are important in the diets of gorillas, and that the gorillas fulfil these nutritional requirements through a combination of different plant parts, shedding new light on how gorillas balance their diets in a variable environment. Am. J. Primatol. 70:927–938, 2008. © 2008 Wiley‐Liss, Inc.