INTRODUCTION

In nature, access to food sources is constrained and, depending on their diet, individuals compete directly or indirectly to meet their nutritional needs. Sometimes, however, food resources can be divided. Division of food has been seen in vertebrates as diverse as the raven (Corvus corax, Heinrich et al. 1995), vampire bat (Desmodus rotundus, Wilkinson 1984), and chimpanzee (Pan troglodytes, Goodall 1968). For mammalian species, reports on food sharing are mostly for primates and, within this order, Pan dominates the other genera.

In chimpanzees, food sharing occurs most often between mother and dependent offspring (McGrew 1975; Nishida & Turner 1996) and involves plant food. Although food sharing between mature individuals sometimes involves plant food (Lanjouw, Chapter 3; Watts & Mitani, Chapter 18), it is more common in the context of hunting and meat consumption. Hunting of mammalian prey has been reported from all sites where chimpanzees have been studied long term: Assirik (Hunt & McGrew, Chapter 2), Budongo (Suzuki 1975), Gombe (Goodall 1968; Stanford 1995), Kahuzi (Basabose & Yamagiwa 1997), Lopé (Tutin & Fernandez 1993), Mahale (Nishida et al. 1979), Ngogo (Mitani & Watts 1999), Kanyawara (Wrangham, personal communication), Ndoki (Kuroda et al. 1996), Taï (Boesch & Boesch 1989), Tongo (Lanjouw, Chapter 3), Sapo (Anderson et al. 1983), and Semliki (Hunt & McGrew, Chapter 2).

Frequency and style of hunting vary both within and across sites, and appears to be affected by forest structure, prey species and group composition (Lenglet 1987; Boesch 1994; Stanford 1998a; Boesch et al., Chapter 16). Accordingly, food sharing is also likely to vary across different sites or populations.