Role of grooming in reducing tick load in wild baboons (Papio cynocephalus)

Nonhuman primate species spend a conspicuous amount of time grooming during social interactions, a behaviour that probably serves both social and health-related functions. While the social implications of grooming have been relatively well studied, less attention has been paid to the health benefits, especially the removal of ectoparasites, which may act as vectors in disease transmission. In this study, we examined whether grooming behaviour reduced tick load (number of ticks) and haemoprotozoan infection status in a population of wild adult baboons (Papio cynocephalus). We found that younger and higher-ranking adults were groomed more often than older, low-ranking adults, and females were groomed more often than males. Animals that received more grooming, in turn, had lower tick loads. Baboons with lower tick loads had higher packed red cell volume (PCV or haematocrit), one general measure of health status. We detected a tick-borne haemoprotozoan, Babesia microti, but its low prevalence in the population precluded identifying sources of variance in infection.