Copulatory behavior of prairie voles (Microtus ochrogaster) in a two-male situation

Two experiments were conducted to study the dynamics of copulatory and aggressive behavior in situations where two sexually active male prairie voles were tested with a single receptive female. In Experiment I, 20 males were each tested once in a one-male condition and once in a two-male condition. Although the basic copulatory pattern was identical in both situations, a facilitation, manifested as decreased numbers of mounts, intromissions, and thrusts prior to the first ejaculation, occurred in the two-male condition. In Experiment II, 24 males each received two additional two-male tests conducted in their home cages. Although there were stable dominance relationships and differences in ejaculation frequency, there were no consistent differences between dominant and subordinate males with respect to copulation.