Biological market theory predicts that animals exchange the same commodities, or interchange different ones, to their
mutual benefit. Using focal and behavioral sampling methods and continuous recording techniques, we studied Tibetan macaques
( Macaca thibetana
) in two study groups (YA1 and YA2) at Huangshan, China to see whether adults interchanged male-to-female agonistic support for copulation. Overall, male-to-female agonistic support was significantly correlated with copulation behaviors when data from both study groups were combined. For YA1, copulations in post-agonistic support observation (PO) was greater, but not significantly so, than random observation (RO) in the breeding season, and copulation in PO was significantly greater than RO in the non-breeding season. For YA2 copulations in PO were significantly greater than RO in both breeding and non-breeding seasons.
These results suggest that a male who extends post-agonistic support to a female is significantly more likely to copulate with her. Our
study provides evidence for the existence of a biological market involving interchanged social behaviors. Our study also illuminates
the reproductive strategies of male competition and female choice in this species.