Telemetered heart rates (HR) were correlated with social interactions of adult free-ranging Bighorn sheep (0vi.s canadensis canadensis). Minimal cardiac responses suggest that economy of expression is a pervasive feature of social behaviour in this species. Commonly performed courtship, dominance and agonistic displays elicited few HR responses in either sender or receiver; those that did occur, were transitory and usually accompanied motor reactions by the subject. Intense behavioural acts that occurred infrequently, such as mount attempts, rush-charges and clashes, evoked maximal HR increases in both performer and receiver. These findings are consistent with the complex social behaviour of Bighorn sheep and a life-strategy demanding frugal investment of resources in maintenance, in order to maximize growth and reproduction.