Reciprocal allogrooming in impala, Aepyceros melampus

Abstract

Adult female and male impala engage in a type of allogrooming in which partners alternately deliver bouts of oral grooming to the head and neck. These grooming encounters comprise typically six to 12 tit-for-tat-like exchanges of bouts and are highly reciprocal among adult females, adult bachelor males and subadult males. Although allogrooming among females could be between related individuals, that occurring among adult males would appear to be between unrelated individuals. Unlike allogrooming reported for some primate species and other ungulates, the dominant impala received no more grooming than the subordinate. It is proposed that one function of impala allogrooming is to reduce the ectoparasite load on body areas an animal cannot reach with its own mouth. The impala reciprocal allogrooming system is unique among free-ranging antelope and other ungulates and may be a candidate for the tit-fortat strategy of evolved cooperation.