Sexual Initiating Behaviour By Female Rhesus Monkeys (Macaca Mulatta) Under Laboratory Conditions

Observations were made on oppositely-sexed pairs of adult rhesus monkeys during 60-min tests when females were both intact (215 tests) and ovariectomized (196 tests). Three special gestures, named the hand-reach, head-duck and head-bob were described in female rhesus monkeys, and evidence is put forward that, like the well-known "presentation" gesture, they too served as female sexual invitations. They occurred most frequently immediately before and during the mounting sequence and ceased abruptly after the male's ejaculation. Although individually less effective than presentations in stimulating mounting by males, hand-reaches, head-ducks and head-bobs together initiated a larger total number of mounts: thus, they were important invitational gestures. Ovariectomy resulted in a dramatic decrease in the numbers of these sexual invitations as female receptivity declined. Hand-reaches, head-ducks and head-bobs possessed some of the stereotyped properties of reflexes and, unlike presentations, never occurred in non-sexual behavioural situations or in response to a non-sexual stimulus (e.g. male threat) ; they may thus provide a more direct indication of the female's motivational state.