Gestation and inter-birth intervals in the owl monkey (Aotus trivirgatus griseimembra).

A single, timed mating indicated a gestation period of 133 days for Aotus trivirgatus griseimembra. This figure is confirmed by approximate correspondence with minimum inter-birth intervals, results from radioimmunoassay of urinary oestrogens during pregnancy, and general agreement with a logarithmic plot of gestation period against body weight for simian primates. Birth data indicate that owl monkey females in present colonies in captivity breed throughout the year and will, on average, produce 3 infants every 2 years. There is no evidence of a characteristic post-partum oestrus.