The amount of plant foods eaten and sexual differences in food intake among chimpanzees in Kibale Forest was investigated between July 2007 and January 2008. Continuous focal animal sampling was used to collect data on the diet, number, and duration of feeding bouts of 18 individuals of the Kanyawara chimpanzee community. Chimpanzees utilized 42 plant species for fruits, leaves, and piths. Among plant parts eaten, fruits contributed the greatest percentage of fresh weight (18) in the diets compared to leaves (5.1) and piths (3.6). The duration of feeding bouts varied, ranging from 1.5 to 45.8 minutes. When Mimusops bagshawei fruits were eaten, the numbers of feeding bouts per chimpanzee per day were high compared to when they were not. While our study agrees with previous studies that females spend more time feeding per day, it shows that the long feeding time among females does not translate to increased food weight. We suggest that the social role of females in taking care of the young and their attention being taken up by this role while feeding and fears associated with male presence is the reason for long feeding time among females. 1. Introduction Food availability varies both in time and space and there are reports of seasonal and dramatic interannual variations in the sources and quantities of food [1–4]. As a result, the diets of primate species are expected to change with food availability. The diet of wild chimpanzees is highly diverse and includes fruits, blossoms, barks of trees, leaves, and leaf buds. Although their diet includes many vegetables, they prefer fruit [5–10], and they supplement with a variety of insects, birds’ eggs, birds [11], and small to medium-sized mammals [11–15]. Chimpanzee diet is more diverse when food is scarce. During this time stems, barks, underground storage organs and insects are eaten [11]. Consumption of Terrestrial Herbaceous Vegetation (THV) by the Kanyawara community chimpanzees increases as an alternative (fallback) resource when fruit is scarce [16]. Kanyawara chimpanzees preferentially consume arboreal drupes when available [17, 18]. When drupes are not available, figs are eaten in spite of their low sugar content compared with drupes [19]. Studies using feeding duration have shown that female chimpanzees spend more time feeding than males [20–22]. Although several studies on chimpanzee feeding ecology have been undertaken at different study sites: in Tanzania, [13], and Uganda [7, 9, 17, 23–25], no study has systematically estimated the weight of food eaten by wild chimpanzees or assessed the
References
[1]
A. Whiten and E. M. Widdowson, Foraging Strategies and Natural Diet of Monkeys, Apes and Humans, Oxford Science Publications, New York, NY, USA, 1992.
[2]
R. W. Wrangham, C. A. Chapman, A. P. Clark-Acardi, and G. Isabirye-Basuta, “Socioal ecology of Kanyawara chimpanzees: implications for understanding the costs of great ape groups,” in Great Apes Societies, T. Nishida, Ed., Cambridge University Press, Cambridge, UK, 1992.
[3]
C. A. Chapman, R. W. Wrangham, and L. J. Chapman, “Ecological constraints on group size: an analysis of spider monkey and chimpanzee subgroups,” Behavioral Ecology and Sociobiology, vol. 36, no. 1, pp. 59–70, 1995.
[4]
R. W. Wrangham, N. L. Conklin-Brittain, and K. D. Hunt, “Dietary response of chimpanzees and cercopithecines to seasonal variation in fruit abundance. I. Antifeedants,” International Journal of Primatology, vol. 19, no. 6, pp. 949–970, 1998.
[5]
M. C. Ghighilieri, The Chimpanzees of Kibale Forest. A Field Study of Ecology and Social Structure, Columbia University Press, New York, NY, USA, 1984.
[6]
T. Kano, The Last Ape. Pygmy Chimpanzee Behavior and Ecology, Stanford University Press, 1986.
[7]
G. Isabirye-Basuta, “Feeding ecology of chimpanzees in the Kibale Forest, Uganda,” in Understanding Chimpanzees, P. Heltne and L.A . Marquardt, Eds., pp. 116–127, Harvard University Press, Cambridge, Mass, USA, 1989.
[8]
T. Nishida, “The chimpanzees of the mahale mountains. Sexual and life history strategies,” International Journal of Primatology, vol. 12, no. 6, 1991.
[9]
N. E. Newton-Fisher, “The diet of chimpanzees in the Budongo Forest Reserve, Uganda,” African Journal of Ecology, vol. 37, no. 3, pp. 344–354, 1999.
[10]
C. Boesch and H. Boesch-Achermann, The Chimpanzees of Tai Forest. Behavioral Ecology and Evolution, Oxford University Press, Oxford, UK, 2000.
[11]
J. Goodall, The Chimpanzees of Gombe. Patterns of Behaviour, The Belknap Press of Harvard University Press, Cambridge, Mass, USA, 1986.
[12]
A. Suzuki, “Carnivority and cannibalism observed among forest-living chimpanzees,” The Anthropological Society of Nippon, vol. 79, pp. 30–48, 1971.
[13]
R. W. Wrangham, “Feeding behaviour of chimpanzees in Gombe National Park, Tanzania,” in Primate Ecology, pp. 503–538, Academic Press, London, UK, 1977.
[14]
T. Nishida, S. Uehara, and R. Nyundo, “Predatory behavior among wild chimpanzees of the mahale mountains,” Primates, vol. 20, no. 1, pp. 1–20, 1979.
[15]
I. C. Gilby and R. W. Wrangham, “Risk-prone hunting by chimpanzees (Pan troglodytes schweinfurthii) increases during periods of high diet quality,” Behavioral Ecology and Sociobiology, vol. 61, no. 11, pp. 1771–1779, 2007.
[16]
R. K. Malenky and R. W. Wrangham, “A quantitative comparison of terrestrial herbaceous food consumption by Pan paniscus in the Lomako Forest, Zaire, and Pan troglodytes in the Kibale Forest, Uganda,” American Journal of Primatology, vol. 32, no. 1, pp. 1–12, 1994.
[17]
R. W. Wrangham, N. L. Conklin, C. A. Chapman, and K. D. Hunt, “The significance of fibrous foods for Kibale Forest chimpanzees,” Philosophical Transactions of Royal Society of London B, vol. 334, no. 1270, pp. 171–178, 1991.
[18]
M. Thompson, Endocrinology and ecology of wild female chimpanzee reproduction [Ph.D. thesis], Department of Anthropology, Harvard University, Cambridge, Mass, USA, 2005.
[19]
N. L. Conklin and R. W. Wrangham, “The value of figs to a hind-gut fermenting frugivore: a nutritional analysis,” Biochemical Systematics and Ecology, vol. 22, no. 2, pp. 137–151, 1994.
[20]
J. D. Bygott, Agonistic behavior and dominance in wild chimpanzees [Ph.D. dissertation], Cambridge University, 1974.
[21]
R. W. Wrangham, The behavioural ecology of chimpanzees in Gombe National Park, Tanzania [Ph.D. thesis], University of Cambridge, 1975.
[22]
K. H. Farmer, H. M. Buchanan-Smith, and A. Jamart, “Behavioral adaptation of Pan troglodytes troglodytes,” International Journal of Primatology, vol. 27, no. 3, pp. 747–765, 2006.
[23]
R. W. Wrangham, N. L. Conklin, G. Etot et al., “The value of figs to chimpanzees,” International Journal of Primatology, vol. 14, no. 2, pp. 243–256, 1993.
[24]
M. Chemurot, Food Consumption and Rest Time in Chimpanzees (Pan Troglodytes) of Kanyawara Community [Unpublished M.S. thesis], Makerere University, Kibale National Park, Uganda, 2009.
[25]
N. E. Newton-Fisher, V. Reynolds, and A. J. Plumptre, “Food supply and chimpanzee (Pan troglodytes schweinfurthii) party size in the Budongo Forest Reserve, Uganda,” International Journal of Primatology, vol. 21, no. 4, pp. 613–628, 2000.
[26]
G. Isabirye-Basuta, The ecology and conservation status of the chimpanzee (Pan troglodytes Blumenbach) in Kibale Forest, Uganda [Ph.D. thesis], Makerere University, Kampala, Uganda, 1990.
[27]
C. A. Chapman and R. W. Wrangham, “Range use of the forest chimpanzees of kibale: implications for the understanding of chimpanzee social organization,” American Journal of Primatology, vol. 31, no. 4, pp. 263–274, 1993.
[28]
M. A. Huffman, “Current evidence for self-medication in primates: a multidisciplinary perspective,” Yearbook of Physical Anthropology, vol. 40, pp. 171–200, 1997.
[29]
R. Fagen, “Primate juveniles and primate play,” in Juvenile Primates, M. E. Periera and L. A. Fairbanks, Eds., pp. 182–196, Oxford University Press, Oxford, UK, 1993.
[30]
H. Pontzer and R. W. Wrangham, “Ontogeny of ranging in wild chimpanzees,” International Journal of Primatology, vol. 27, no. 1, pp. 295–309, 2006.
