Communication of ovulatory state to mates by female pygmy marmosets, Cebuella pygmaea

Abstract

In monogamous and polyandrous species of primates it has been suggested that reproductive status is concealed rather than communicated. The generally monogamous pygmy marmoset shows few, if any, observable signs of ovulation, but it is still possible that the female's reproductive state is communicated to the male. The sexual behaviour of 10 pairs of captive pygmy marmosets was observed during 30-min tests for 60 consecutive days after pairing. Urine was collected daily from females for the measurement of luteinizing hormone and oestradiol. Sexual behaviour occurred throughout the ovarian cycle of 36–37 days and the conception rate was 83%. Female marmosets did not alter rates of scent-marking across the ovarian cycle, however, male marmosets showed significantly more responses to female anogenital scents and increased rates of mounts, piloerection and staring (courtship behaviour) during their mate's peri-ovulatory period. In addition, female aggression towards the male was observed only during non-ovulatory periods suggesting that an absence of aggressive behaviour may serve as a cue to ovulation. This is the first evidence that the female pygmy marmoset's reproductive state is communicated directly to the male, suggesting that qualitative changes in female olfactory cues or decreased female aggression can affect male sexual behaviour.