Sexual activity of male rhesus monkeys introduced into a heterosexual group.

Unfamiliar males were introduced during the breeding season to a stable heterosexual group of rhesus monkeys to determine how the presence of more dominant resident males affected their mating activity and how their entry was received by resident females. Initially, new males were allowed access to females under controlled conditions both in the presence and absence of resident males, simulating situations which may occur under natural conditions. Results indicated that the sexual activity, including ejaculation rate, of the new males was initially inhibited by the presence of more dominant, resident males, but these inhibiting properties did not carry over to periods when the resident males were absent and were diminished with time. Group females preferentially directed their behavior towards the new males throughout the study. These data suggest that although entry of new males into a stable group is at low rank, their subsequent reproductive success may not be reduced and that the association with resident females may facilitate male rhesus transfer between groups observed during the breeding season.