Abstract
The Copulatory behavior of sexually inexperienced male hamsters paired with natural proestrous females was observed between 1900 and 2000 hours under dim red light illumination. Each male was allowed 30 min to mate with a receptive female. Five out of 7 males showed at least one ejaculation within 30 min. Although the copulatory behavior of the above males was observed again, the activities of copulatory behavior did not facilitate.