A Quantitative Description of Copulatory Behavior in Prairie Voles <i>(Microtus ochrogaster)</i>

Abstract

Copulatory behavior in M. ochrogaster wasexamined under laboratory conditions in two experiments. In the first experiment, eight pairs each receivedfive tests of copulatory behavior continued to a satiety criterion of 30 min with no intromission. Females were brought into behavioral estrus with exogenous hormones.The basic copulatory pattern involved no lock, intra-vaginal thrusting, multiple intromissions, and multiple ejaculations. Males typically exhibited only 2 ejaculations before attainment of the satiety criterion. Tests of a Coolidge effect were also conducted, and there was no reliable resumption of copulation by satiated males following introduction of new, estrous females. A second experiment involved the observation of 10 pairs, with the females in natural estrus. Each pair received one test of copulatory behavior. There were no substantial differences in the behavior observed in the second experiment as compared to the first. Variations in copulatory behavior patterns within the genus <i>Microtus </i>were discussed, and a possible role for these variations in the maintenance of reproductive isolation was suggested.