Rat Mating Behavior

Among complex land animals, an elaborate courtship usual, but rats and other small mammals are exceptions. If an adult male, recently deprived of female complany, encounters a female, he approaches and sniffs her; he may sniff and lick her genetalia, or he may omit this formality and try to mount her. If the female is in estrus she may herself take the initiative in approaching the male and nosing him. After the first contact she runs a short distance (if space allows); and pauses, the male follows and mounts her; as the male presses on the female's flanks, she adopts a posture (lordosis) which permits intromission, with the coccygeal region raised and the tail to one side.

The male performs pelvic thrust and, if ejaculation does not occur, then leaps backwards. The whole contact takes only a few seconds. After the backward leap the male sits on his haunches and licks his penis. If ejaculation occurs, the male does not leap back, but pauses and then usually falls off to one side of the female.

In a typical encounter, about five initial intromissions occur at short intervals without ejaculation; on the sixth, the female is inseminated; and there is then a refractory period of a few minutes, after which the sequence is repeated, but with fewer preliminary intromission before ejaculaton. The refractory periods lengthen, but ejaculations occur progressively earlier once intromission have resumed. There is consequently an apparent anomally; as the readiness to copulate declines, the readiness to ejaculate increases.