Studies with timed-pregnant squirrel monkeys (Saimiri sciureus)

Timed-pregnant monkeys were produced in a large nonhabituated colony of Saimiri sciureus of Bolivian origin. In a colony of 373 females and 40 males, 277 females (74%) were considered to be inseminated, based on microscopic observation of sperm and/or detection of a coagulum (plug) in the vagina. Forty-six full-term progeny were delivered. The mean gestational period was 152.5 days (SD = 3.9 days). For continuous cohabitation, the median time to insemination was five days, with 75% of inseminations occurring within eight days. Pregnancy evaluation (mouse bioassay) indicated a high level of resorptions within the first 50 days of gestation. This may help explain the low birth rates reported for other nonhaibuated colonies.