Reproductive cycles of two Cercopithecus monkeys.

Abstract

Summary. Reproductive cycles of female vervets and Sykes' monkeys living in caged breeding groups were followed over 2 years, using a vaginal lavage technique. Both species showed menstrual cycles, and both showed leucocyte peaks in mid-cycle which were assumed to be associated with ovulation. Vaginal cornification patterns were dissimilar in the two species. Sykes' monkeys showed some limitation of copulation to an oestrous period but this was not at a constant stage in the cycle. Vervets appeared to be in continuous oestrus. The gestation period of vervets was confirmed at 165 days and that of Sykes' at about 140 days, which was correlated with a slower rate of development in the infant Sykes'. The caged Sykes' showed two breeding seasons annually, conceptions occurring in the dry seasons but free-living animals are reported as having one breeding season a year. Vervets had a single, long birth season as in the wild but not at the same time as nearby wild groups and not apparently associated with wet or dry seasons.