Prolonged copulatory behavior facilitates pregnancy success in the musk shrew

Female musk shrews (Suncus murinus) are sexually receptive and actively seek contact with males during the first ten days of pregnancy. In the series of experiments reported here we examined the effects of prolonged copulatory behavior on pregnancy success. Females received multiple ejaculations either on the same day or over the course of up to six days. When ejaculations were distributed over an interval of several days, the number of females delivering litters was significantly increased. The same outcome was found regardless of whether the first fertile mating was followed by subsequent copulations with normal or vasectomized males. One ejaculation followed by daily contact with soiled bedding taken from a male's cage did not increase pregnancy rates. Three ejaculations received over a three-day interval caused significantly more females to ovulate than three ejaculations given on the same day. The results demonstrate that prolonged copulatory behavior, which includes vaginocervical stimulation, facilitates ovulation and pregnancy in this species.