Eastern chipmunks typically emerge above ground in late March, at a time when most mature females are in breeding condition. It takes little time for nearby males to come courting. During their breeding period, females, for the most part, remain within their territory, whereas males explore within and outside of their territories in search of a receptive female.
Male suitors congregate on the site of a female in estrus and work out the hierarchy within the group. The top chipmunk wins the opportunity to breed with the female. During these dominance battles, the males vocalize, wave their upright tails from side to side, chase each other and fight. The dominant male then breeds with the female. She proceeds to mate anywhere from 10 to 30 times within about a six to seven-hour receptive period, not necessarily with the same male. All of this activity takes place within a week of when chipmunks come above ground, so keep your eyes peeled for those waving tails.
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