Grooming Interactions Among the Chimpanzees of the Budongo Forest, Uganda: Tests of Five Explanatory Models

Abstract

AbstractPatterns of allogrooming among the Sonso community of chimpanzees of the Budongo Forest, Uganda, were examined and found to closely resemble those at other study sites. Strong affiliative bonds among males were reflected in high levels of grooming compared with other sex combinations. Adult males groomed, and received grooming most often from, other adult males and also adolescent females which were the only females with regular oestrous cycles during the study. Males had a wider diversity of grooming partners than females and groomed more equitably. However, males concentrated the majority of their effort on a very small number of partners compared with other sites. Grooming reciprocity was found among all age/sex combinations with the exception of adult male-female dyads once immediate reciprocation in the form of synchronous mutual grooming was removed from the analysis. Since grooming among males is thought to play a major role in servicing relationships and agonistic coalitions that can improve dominance status, competition for high-ranking grooming partners was predicted to influence the distribution of grooming among males. Grooming was indeed directed up the male hierarchy and closely ranked males groomed each other more often than those that were distantly ranked. However, when only adult males were considered, rank had little effect on grooming distributions. High rank appeared to influence access to females, but did not attract more female grooming partners. Grooming distributions in this average-sized community did not fit a number of alternative priority of access models which assume competition for high-ranking grooming partners that Watts (2000b) found to have some explanatory value in one very large community of chimpanzees, but not in a smaller, more representative one. Although rank is highly likely to influence coalition partner choice, whether such relationships depend upon strategic grooming partner choices in wild chimpanzees is presently unclear.