If, however, she is in season, she may respond in kind. In fact, some females will even advertise their readiness to mate even if the male is not aroused. The female will lower her head and rumble just like the male does, and will raise her bottom slightly into the air. She may even wag her bottom slightly to attract the male's attention. The male may circle her a few times before positioning himself behind her to mount.
Copulation lasts only a few seconds.
They may mate several times each hour, sometimes as frequently as a few minutes apart. The gestation period for guinea pigs is typically between 60 and 70 days. Longer gestation times tend towards smaller litters, whereas shorter times tend towards large litters. The average litter size is 2 to 4, though they can carry as many as 8 or as few as 1. She may also demand more pellets and fresh vegetables, to aid in lactation and in providing for her developing babies.