COMMUNICATION OF OVULATORY STATE TO MATES BY FEMALE PYGMY MARMOSETS, CEBUELLA-PYGMAEA

In monogamous and polyandrous species of primates it has been suggeste d that reproductive status is concealed rather than communicated. The generally monogamous pygmy marmoset shows few, if any, observable sign s of ovulation, but it is still possible that the female's reproductiv e state is communicated to the male. The sexual behaviour of 10 pairs of captive pygmy marmosets was observed during 30-min tests for 60 con secutive days after pairing. Urine was collected daily from females fo r the measurement of luteinizing hormone and oestradiol. Sexual behavi our occurred throughout the ovarian cycle of 36-37 days and the concep tion rate was 83%. Female marmosets did not alter rates of scent-marki ng across the ovarian cycle, however, male marmosets showed significan tly more responses to female anogenital scents and increased rates of mounts, piloerection and staring (courtship behaviour) during their ma te's peri-ovulatory period. In addition, female aggression towards the male was observed only during non-ovulatory periods suggesting that a n absence of aggressive behaviour may serve as a cue to ovulation. Thi s is the first evidence that the female pygmy marmoset's reproductive state is communicated directly to the male, suggesting that qualitativ e changes in female olfactory cues or decreased female aggression can affect male sexual behaviour.