Baboon diet: a five-year study of stability and variability in the plant feeding and habitat of the yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania

The habitat and plant feeding of 64 well-habituated, individually identified adult male and female yellow baboons was studied for 5 years at Mikumi National Park, Tanzania. Variation across the years showed that a study of only one or two years would have been incomplete and misleading. The list of baboon food species obtained from Mikumi is considerably larger and more diverse than any previously reported. One to six plant parts were eaten from each of more than 180 species. The 25 most common tree genera all contained species used for food. Of the 50 most common grass, shrub and herb genera, 93% included plant foods. Using months in which a species was eaten during at least one year of the study, 21 staple species were eaten during a mean of 8.86 months and 7 were eaten in all 12 months. Although many foods were from commonly available plant species, 15 such species were only rarely eaten. The number of parts of a species eaten per month and an estimate of the amounts eaten per month both varied with temperature and rainfall, being lowest near the end of the cool, dry season. There were substantial differences from year to year in the timing and amount of food production of many species; nevertheless, the same broad feeding pattern was repeated in each of the 5 years of the study. Despite yearly variation in food availability, 14 or more staples and other common foods were eaten in any given month. If crops of many of these foods were to fail, a large number of less commonly eaten species could be substituted. Baboons are eclectic feeders that appear to be optimizing their diet by selective feeding from among a wide array of available foods in an ever-changing floristic environment.     

Influence of Dry Season and Food Quality and Quantity on Behavior and Feeding Strategy of Propithecus verreauxi in Kirindy, Madagascar

According to optimal foraging theory, herbivores can base food choice mainly on the quality or the quantity of food, or both. Among herbivorous primates, folivorous lemurs living in the highly seasonal environment of Madagascar have to cope with the shortage of high-quality food during the dry season, at least in deciduous forests. We studied (Verreaux's sifaka) in Kirindy, western Madagascar, to understand the influence of dry season and food quality and quantity on behavioral patterns and feeding strategy (qualitative vs. quantitative dietary choice) of a folivorous lemur in a deciduous forest. We followed 7 groups (4 groups/period; 3 individuals/group/month) during 4 periods of the year (wet season: February–March; early/middle/late dry season: May–June; July–September; October–November). We collected samples of plants eaten and examined behavioral and feeding patterns, considering food quality (macronutrients, proteins/fibers ratio, and tannins) and abundance. We found 1) a significant reduction of home range, core area, and daily path length from the wet to the dry season, possibly related to dietary change and 2) a daily period of inactivity in the dry season for energy conservation. Regarding the feeding strategy, Kirindy sifakas showed 1) high variation and selection in choosing food items and 2) a dietary choice based mainly on quality: Kirindy sifakas fed on plant species/families independently from their abundance and tannins represented a feeding deterrent during the dry season. Overall, behavioral and dietary adaptations allow Kirindy sifakas to overcome the shortage of high-quality food in the lean period.     

Diet and feeding behaviour of samango monkeys (Cercopithecus mitis labiatus) in Ngoye Forest, South Africa

The samango monkey occurs at the southern limit of the range of Cercopithecus mitis. Greater climatic seasonality at this latitude results in more predictable fruiting patterns. In addition, there are no diurnal sympatric primate frugivores. Under these conditions, the diet and feeding strategies of samango monkeys would be expected to differ notably from those of central or east African C. mitis subspecies. Contrary to these expectations, the preliminary observations reported here indicate that diets of samango and blue monkeys differ only superficially in the proportions of items eaten. Similarities in feeding behaviour are especially marked during the dry season period when fruit is not abundant. Both samango and blue monkeys tend to be less selective in their choice of food species and to eat available food species regardless of their energy content; a shift toward less nutritious items such as leaves is also noted. Feeding behaviour during the summer wet season is characterized by the selection of fruits with high-energy values. A high proportion of visits by the monkeys to areas of greater food availability suggests a concentration of feeding effort in food patches and the selection of higher energy food species within patches.     

Ontogenetic diet shifts and resource partitioning among piscivorous fishes in the Venezuelan ilanos

Synopsis Resource utilization by nine abundant piscivores from a diverse tropical fish assemblage was examined over the course of a year. All nine species exhibited peak reproduction during the early wet season and a similar sequence of size-dependent shifts from a diet composed primarily of microcrustacea, to aquatic insects, and finally fishes. Three piranha species specialized on fish fins, particularly at subadult size classes (SL 30–80 mm). Gradual dessication of the floodplain during the transition season was associated with fish growth, increased fish density, and decreased aquatic primary productivity and availability of invertebrate prey. Based on 118 resource categories, average pairwise diet overlap was low during all three seasons: wet, transition, and dry. Of 72 species pairings, only one pair of fin-nipping piranhas exhibited high overlap simultaneously on three niche dimensions: food type, food size, and habitat. Adults of two species, a gymnotid knifefish and pimelodid catfish, were largely nocturnal. Patterns of habitat utilization indicate that piranhas may restrict diurnal use of the open-water region by other piscivores. Collective diet overlap of individual piscivore species with the other eight feeding guild members and collective overlaps with the entire fish community each revealed two basic seasonal trends. Four species that showed an early switch to piscivory also showed a high degree of diet separation with both the guild and community at large on a year-round basis. The five remaining species showed lowest collective diet overlaps during the transition season when availability of invertebrates was reduced and fish densities were maximal. Whereas predation may play a role in habitat separation, diffuse competition for food resources during the approximately four-month transition season probably is the principal factor yielding patterns of diet specialization.     

Feeding habits of guanacos<Emphasis Type="Italic">Lama guanicoe</Emphasis> in the high Andes of north-central Chile

The guanacoLama guanicoe Muller, 1776 has a wide distribution along the Andes and Patagonia. We studied the feeding behaviour of a guanaco population that lives over 4100 m altitude in the Andes of north-central Chile. By contrasting the diet of guanacos during a dry year with that of a wet year and comparing it with the plant availabilities in the field, we tested the hypothesis that the guanaco is a generalist herbivore. We predicted that under such extreme habitat conditions guanacos should consume whatever plant species are available in the environment, especially in a dry year, when vegetation is scarcer. In addition, we compared its diet at three different age classes. We estimated the diet through the microhistological analysis of plant remains found in guanaco pellets collected during January of 1997 (ie after a dry year) and 1998 (ie after a wet year; 41 vs 495 mm, respectively). Then, we computed dietary preferences, food niche-breadth, and food-niche overlap between years and among age classes. Vegetation cover and plant species richness were higher during the wet than during the dry year. The most common plants in the environment were perennial graminoids and legumes. Contrary to our prediction, the guanaco preferred a few plant species, showing a relatively narrow diet breadth that changed little between years differing in plant abundances. The diet proportions differed among the three age classes, however. Our data indicate that at least in this high-elevation population, guanacos are selective and non-opportunistic herbivores. This specialized feeding behaviour is puzzling given the energetic demands of living in a harsh environment with low availabilities of resources. The hypothesis that this is due to the lower palatability of the plants not eaten, remains to be tested.     

Seasonal and geographical influences on the feeding ecology of giraffes in the Luangwa Valley,Zambia: 1973–2014

Obtaining longitudinal data about the feeding ecology of long‐lived iteroparous mammals is rare, but enhances our understanding of how the environment influences niche breadth and dietary diversity within a species. We analysed forty years of feeding records obtained from a population of Thornicroft's giraffes (Giraffa camelopardalis thornicrofti) living in the Luangwa Valley, Zambia. Giraffes are browsers that have been reported to feed primarily upon Acacia leaves, but their feeding ecology in some locations conflict with this interpretation. Giraffes in the Luangwa Valley fed on 93 identified plant species, but only a few contributed to the bulk of the diet. Niche breadth was quite large (Shannon‐Weiner Diversity Index H′ = 3.699) and about 13% more diverse during the dry, than wet, season. Key species eaten during the dry season were very consistent across decades, with Kigelia africana and Capparis tomentosa prominent at this time. The evolutionary ecology of giraffes has probably benefitted from a foraging strategy that includes a variable and high‐quality diet during the hot, dry season, when feeding pressures are greatest. Giraffe feeding ecology has evolved in conjunction with their physiology, anatomy and morphology, resulting in an animal that is well adapted for survival in an arid environment.     

Observations on the ontogeny of feeding behavior in mountain gorillas (Gorilla gorilla beringei)

This report describes observations on the ontogeny of food choice in mountain gorillas (Gorilla gorilla beringei), made during a 17-month field study of mountain gorilla feeding ecology in the Parc National des Volcans, Rwanda. Data are presented on the feeding behavior of two infants observed from birth to the age of 8 months and on older infants and juveniles. This information is compared with data on the composition and diversity of the diets of young adults and adults in the same social group. Initial feeding by infants is usually synchronized with the mother's behavior: infants ingest the same food, or a different part of the same plant species, currently being eaten by the mother or just eaten by her. This suggests that observational learning is largely responsible for the transmission of food preferences. Most feeding by young infants, whether or not synchronized with the mother's, is on those foods eaten most frequently by adults. Infants also independently sample potential foods, some of which are apparently not consumed by adults. The frequency of sampling declines with age, although even adults occasionally ingest foods not observed to be eaten by other adults. By the age of 3 years, young mountain gorillas have developed the basic dietary patterns of adults, in terms of the number of foods eaten, the proportions in which specific foods are consumed, and diet diversity and equitability. There is a strong possibility that chemical cues influence food choice, but their role remains unclear.     

Activity pattern of the brown howler monkeyAlouatta fusca,Geoffroy 1812, in a forest fragment of southeastern Brazil

A group of six brown howlers was studied during a year in the Santa Genebra Reserve, a 250ha-forest fragment near the city of Campinas, State of São Paulo, southeastern Brasil. On average, the group rested for 64% of the daylight hours and feeding and moving occupied 18% and 13% of this period, respectively. A greater proportion of time was spent feeding during dry season (24%) than the wet season (15%), and the reverse observed for time spent resting (59% and 69% of the group's daylight hours during dry and wet seasons, respectively). The increase of resting and decrease of feeding during wet season were related to the percentage of leaves in the group's diet, high even during the fruiting season (wet season). However, additional data of other groups are necessary to draw conclusions about the effects of habitat disturbance on this population.     

Seasonal variation of food and feeding in burrowing goby <Emphasis Type="Italic">Parapocryptes serperaster</Emphasis> (Gobiidae) at different body sizes

Diet composition and feeding habits of the burrowing fish Parapocryptes serperaster were investigated on different fish sizes across dry and wet seasons in the Mekong Delta, Vietnam. The gut length was positively related to fish length; the gut length was 1.57 ± 0.30 times the total length, which is in the range for omnivore (1–3). Detritus, algae and copepods were the main food items in the foregut. The diet composition showed seasonal and intraspecific variations in all fish sizes. The diet diversity varied with fish size and the dry-wet season pattern, and small fish had a higher diet diversity than large fish. The diet evenness index and Costello graphic analysis indicate that this goby is a generalist feeder and feeds mainly on detritus, followed by diatoms, and could obtain food from the bottom and the water column. The feeding intensity of P. serperaster was higher in the wet season than in the dry season, but was not significantly affected by fish size. The P. serperaster fed on Navicula spp. in the wet season, but on Nitzschia spp. in the dry season. The understanding of food and feeding habits of P. serperaster contributes to our knowledge on feeding adaptation of small-bodied bottom-dwelling gobies to the mud flat habitats in tropical monsoonal regions.     

Seasonal Variation in the Activity Patterns and Time Budgets of <Emphasis Type="Italic">Trachypithecus francoisi</Emphasis> in the Nonggang Nature Reserve,China

Activity patterns and time budgets are 2 important aspects of animal behavior that researchers use to investigate ecological influences on individual behavior. We collected data on activity patterns and time budgets in 1 group of François’ langurs (Trachypithecus francoisi) from August 2003 to July 2004 in the Nonggang Nature Reserve, Guangxi Province, China, via instantaneous scan sampling method with 15-min intervals. The diurnal activity pattern of François’ langurs showed morning and afternoon feeding peaks, with a midday resting peak. Seasonal change was apparent in the activity pattern: 2 significant feeding peaks occurred in the dry season and only 1 significant feeding peak in the rainy season. The group spent an average of 51.5% of the daytime resting. Feeding and moving accounted on average for 23.1% and 17.3% of the activity budget, respectively. Subjects spent little time on social activities, averaging 2% for grooming and 5.5% for playing. Their time budgets showed significant seasonal variation: they spent a greater proportion of time on feeding and less time on resting and grooming in the dry season than in the rainy season. They also differed among different sex-age classes: immatures spent more time playing, whereas adults devoted more time to resting, feeding, and grooming. Correlations between time budgets and food items or food availability clearly indicated that François’ langurs might adopt an energy-maximizing strategy when preferred foods were scarce in the dry season.     

Seasonal variation in activity and diet in a small-bodied folivorous primate,Hapalemur griseus,in southeastern Madagascar

How small-bodied (500–1,200 g) folivorous prosimian primates cope with large amounts of foliage in their diet seasonally has yet to be determined for many species such as Hapalemur griseus, which specializes on bamboo. To address this issue, we present results on seasonal variation in activity and diet from a wild group of H. griseus in southeastern Madagascar. Throughout the study (which was conducted from July–November 1994 and July 1995–February 1996), H. griseus primarily fed on new growth from three species of bamboo: two species of liana bamboo and Cephalostachyum perrieri. Bamboo species were used in different ways seasonally; liana bamboo was consumed more during the dry, cool season, and C. perrieri was eaten more often during the wet, warm season. H. griseus also spent more of their time feeding and traveling than nocturnal folivores of similar body size during the dry season. During the warm wet season, H. griseus decreased the amount of time spent feeding and traveling and rested more often. We hypothesize that seasonal changes in activity may be primarily related to the distribution and availability of food sources and/or reproductive cycles. Am. J. Primatol. 43:211–223, 1997. © 1997 Wiley-Liss, Inc.     

Food and feeding ecology of the rock fowl Picatthartes oreas in Old Oyo National Park, Nigeria

The rock fowl is an endangered species and its food and feeding ecology was studied in the forest zone of Old Oyo National Park, Nigeria. The methods used were direct observation, and fragmentation analysis of faecal and crop content of samples collected during both the wet and dry seasons. The results showed that rock fowl feed on a wide range of species of insects, fruits and flower buds. In the wet season, animal resources represented 54 and 62% of the adult and chick diet, respectively, whereas in the dry season, animal food resources represented about 60% of both adult and the chick diets. There was a significant difference (P < 0.05) in the food composition of the birds between the dry and wet seasons. There was also a significant (P < 0.05) difference in food preference between adults and chicks. Food sharing was not common, although it was observed between rock fowl cockerels and hens. Food search and selection indices were directly related to season and food availability. It was concluded that food scarcity may not be a serious contributory factor in the threat to the rock fowl.     

Diurnal activity budget of African buffalo (Syncerus caffer Sparrman, 1779) in Chebera Churchura National Park,Ethiopia

One of the fundamental questions in animal ecology concerns the activity pattern of animals and the environmental and intrinsic factors that influence such dynamics. This study tested the hypotheses that activity time budgets of the African buffalo appeared to vary by season and times of day and predicted that buffalo would express unequal proportion of time for different activity patterns during the wet and dry seasons in Chebera Churchura National Park (CCNP). An investigation on the diurnal activity budget of the African buffalo was carried out during the wet and dry seasons of 2012–2014 in the Chebera Churchura National Park, Ethiopia, using focal‐animal sampling method. Buffalo spent a greater proportion of the time in feeding and resting/ruminating activities in both the wet and dry seasons. Feeding and resting (lying down and standing) were the predominant activities (87.14% of the diurnal active period), 48.95% time spent feeding during the dry season and 44.91% during the wet season. There was a significant decrease in feeding and an increase in resting from dry seasons to wet seasons. Daytime grazing and resting periods during the wet season were estimated to be 5.39 h and 4.98 h, respectively. Morning and the late afternoon activity peaks were more pronounced during the dry season than the wet season. Therefore, feeding and resting time was influenced by the time of day and the seasons. But there were no significant difference in time allocation for other activities in both the wet and dry seasons. The study has implications for understanding animal activity budget across species, particularly relationships between temperature and season.     

Diet of the Indochinese silvered langur (Trachypithecus germaini) in Kien Luong Karst area,Kien Giang Province

The Indochinese silvered langur (Trachypithecus germaini) is distributed to the west of Mekong River in Cambodia, Lao PDR, Thailand and Vietnam. During a two‐year study, from May 2014 to May 2016, we collected 320.44 hr of behavior, with 17,040 feeding bouts recorded (142 hr) for T. germaini on Chua Hang Karst Mountain, Kien Luong District, Kien Giang Province, Vietnam. Feeding accounted for 45% of the Indochinese silvered langurs’ activity budget. The plant diet of the Indochinese silvered langurs was principally composed of young leaves (58%), followed by mature leaves (9.5%), fruits (22.7%), flowers (4.7%), buds (3.3%), petioles (1.2%), and other (0.5%). A total of 58 plant species were fed on by the silvered langurs, and leaves of eight species (Phyllathus reticulatus, Ficus rumphii, Ficus tinctoria, Ficus microcarpa, Cayratia trifolia, Streblus ilicifolia, Combretum latifolium, and Streblus asper) were fed on throughout the year. P. reticulatus was most frequently eaten (13.9% feeding time, n = 1,733). Food selection differed significantly between months and seasons. The Indochinese silvered langurs ate 27 plant species in the wet season compared with 23 plant species in the dry season. Leaf chemical composition of two food categories, 16 eaten species (with 10 most frequently consumed species and six least consumed species), and four noneaten species, were analyzed. Feeding samples from eaten species in the Indochinese silvered langurs's diet contained lower amounts of condensed tannin, lignin, protein, ash, and lipids, but a higher amount of total sugar compared with samples from noneaten species. Furthermore, the most frequently consumed species contained lower amounts of lignin compared with the less frequently consumed species. Using a generalized linear model with five variables, including neutral detergent fiber (NDF), total sugar, lignin, lipid, and calcium (Ca) indicated that NDF positively correlated and lignin content negatively correlated with feeding records in the diet of these langur.     

Environmental constraints on the foraging behaviour of a dwarf antelope (Madoqua kirkii)

Dik-diks (Madoqua sp.) inhabit semi-arid regions and experience very different conditions of food availability and quality between wet and dry seasons. By comparing the behaviour of dik-diks between these two seasons, we identified environmental constraints affecting their feeding strategies. In both seasons foraging time was limited by high mid day temperatures. In the wet season a high intake rate compensates for the loss in foraging time, but in the dry season water and protein become limiting. To meet minimum daily water requirements in the dry season dik-diks fed on plant species that they avoided during the wet season. Analysis at the plant species level showed higher species selectivity in the wet season than in the dry season. In a multiple regression analysis food species preferences were best explained by relative abundance and water content in the dry season, and by dry matter content in the wet season. In the wet season the daily dry-matter intake of dik-diks in the field was only about 10% higher than the theoretically predicted minimum for a ruminant of this body weight, while protein and water intake were about 3 times as high. This suggests that the most limiting dietary component in the wet season is energy. In the dry season the daily intake of all dietary components is lower than the theoretical minimum required, and also lower than the values suggested by laboratory studies of dik-diks. This dry season deficit is presumably met from body reserves. Dry season water intake was approximately 30% of the intake observed in laboratory studies indicating that dikdiks are even better adapted to arid conditions than suggested by physiological experiments.     

Nutritional ecology of a browsing ruminant, the kudu (Tragelaphus strepsiceros), through the seasonal cycle

The activities and food selection of four hand-reared kudus were recorded in a large fenced enclosure containing natural savanna vegetation in the Nylsvley Nature Reserve, South Africa. Leaves of selected species were analysed chemically for crude protein, fibre constituents, phosphorus, condensed tannin and total polyphenols. Available protein and metabolizable energy were estimated allowing for potential antinutritional effects of tannins.
Leaves of palatable deciduous woody plants and herbaceous forbs formed the main dietary constituents during the late wet season. Foliage from palatable evergreens and robust forbs were added to the diet during the dry season. Towards the end of the dry season unpalatable species of evergreens were eaten. At the start of the growing season new leaves of otherwise unpalatable woody species formed the staple food source, together with fruits of Strychnos spp. Correspondingly, protein and digestible dry matter concentrations in the diet declined to reach a low at the end of the dry season.
Total daily food intake increased to compensate for reduced dietary quality during the dry season, until little edible foliage remained. While the estimated daily intake of protein remained well above maintenance requirements, the estimated metabolizable energy intake fell below requirements during the late dry season. Phosphorus intake may have been submaintenance in the dry season. Nutritional balance was dependent on the availability of particular vegetation components to serve as nutritional stepping stones during crucial times of the year. These included forbs during the late wet season, palatable evergreens in the dry season, and Strychnos fruits plus early-flushing woody plants during the dry season-wet season transition.     

Diet and feeding patterns in the kipunji (<Emphasis Type="Italic">Rungwecebus kipunji</Emphasis>) in Tanzania’s Southern Highlands: a first analysis

The diet and feeding behaviour of the kipunji (Rungwecebus kipunji) was studied over 45 months, the first dietary analysis for this species. During 9498 h of direct observation of 34 kipunji groups, a list of 122 identified foodplants was recorded. The list represents 60 families, including 64 trees, 30 herbs, 9 climbers, 7 shrubs, 6 lianas, 3 grasses and 3 ferns. Kipunji were observed eating bark, young and mature leaves, ripe and unripe fruits, flowers, pith, seed pods, rhizomes, tubers, shoots and stalks. Invertebrates, fungi, moss, lichen, and soil were also eaten. Macaranga capensis var. capensis, an early successional tree, was the most commonly consumed species, with leaves, leaf stalks, pith, flowers and bark all eaten. We demonstrate that the kipunji is an omnivorous dietary generalist, favouring mature and immature leaves, ripe and unripe fruits and bark in similar proportions, with an almost comparable fondness for leaf stalks and flowers. Kipunji appear to be adaptable foragers able to modify their diet seasonally, being more folivorous in the dry season and more frugivorous in the wet. Whereas more ripe fruit is eaten in the wet season, the proportion of unripe fruit remains similar across the year. The proportion of mature leaves and pith increases throughout the dry season at the expense of ripe fruits and bark, and this may compensate nutritionally for the lack of available dry-season ripe fruits. Relatively more pith is eaten in the dry season, more stalks at the end of the dry and beginning of the wet seasons, and bark consumption increases as the rainfall rises.     

Time budget of the green monkey,Cercopithecus sabaeus: Some optimal strategies

Members of a single group of green monkeys spent, on average, 44.8% of their waking time foraging, 46.7% resting, and 8.5% in social activities, over 1 year. There was significant variation in activity budgets over months (ranging from 35 to 55% of the time spent feeding). Diurnal rhythms of feeding and ranging were influenced by the daily cycle of temperature in predictable ways in different seasons: in the dry season, activity was reduced if it was too hot or too cold, while the temperature in the wet season did not affect activities. Feeding was also synchronized among individuals on a finer time scale, irrespective of the time of day. There was closer synchrony when feeding on less common foods. An ecological model of foraging time and energetics was tested, using estimates of the costs and benefits of foraging and predicting how these are optimally balanced in relation to the food density. Both feeding time and distance traveled increased as food availability increased. Costs and benefits were balanced over several days. Comparisons between populations of Cercopithecus aethiopswere made; differences in time budgets were compared with differences in the availability and quality of food. Insufficient comparative data are available for firm conclusions about the role of different energetic and nutritive strategies in population differences.     

Ecological niche differences betweenAlouatta palliata andCebus capucinus comparing feeding modes,branch use,and diet

During the wet season, two sympatric species of primates,Alouatta palliata (mantled howlers) andCebus capucinus (white-faced capuchins), were assayed for feeding niche differences through behavioral and habitat use patterns at Refugio de Fauna Silvestre Curu in Costa Rica. Differences in the use of relative diameter and thickness of branches and five different modes of feeding were compared between the species. White-faced capuchins used more manipulative modes of obtaining food, a wider range of arboreal habitat, and had a more diverse diet than mantled howlers. Mantled howlers may be more restricted than white-faced capuchins in arboreal microhabitat use due to their possible need for large support branches during feeding bouts and resting periods. We report that differences in feeding behaviors, diet, and arboreal habitat use seem to play a large role in separating these species niches.     

The food habits of wild ungulates in Uganda by analyses of stomach contents

Food eaten by six species of ungulates was studied by analysing stomach contents, using the method developed for faecal analyses. Frequency analyses showed that some herbivore species tend to be selective in their feeding. This suggested that availability and growth form of plants may be important in this respect. The observations agreed with those of other workers, which shows that feeding habits are consistent over large areas. In general, herbivores were classified in three groups with regard to preferences; namely pigs, certain antelope, and buffalo and waterbuck. Comparison of the proportions of epidermal fragments of particular grass species present in stomachs in wet and dry seasons showed that significant seasonal differences exist in the diet of most herbivores. Annuals and most members of the Andropogoneae were present in stomachs in larger proportions during the rains for reasons of availability and palatability. Chloris gayana and Sporobolus pyramidalis were usually present in greater proportions in dry seasons. Differences in the proportions of epidermal fragments of particular plant species present within wet or dry seasons were usually insignificant. A few herbivores, however, showed significant differences within seasons. This indicates that they are sensitive to small changes in plants and that they may have a feeding cycle involving a gradual and regular alternation of plant species. A comparison of the proportions of fragments of the same plant species in different herbivores showed that animal species usually avoided competition by their specialized food habits. There was greater separation in the longer dry season, but competition may have occurred when food supplies were reduced by large herbivores such as buffalo and hippopotamus.