For the first time at the San Diego Zoo (SDZ), the critically endangered Pacific pocket mouse is able to be born, reproduce and give birth within the same breeding season, according to a media report.
It isn’t a surprise to biologists that the mice are capable of this type of breeding behavior. However, San Diego Zoo officials say they never previously observed this in their captive breeding program.
Three female “young of the year” Pacific pocket mice that were born in April at the San Diego Zoo Safari Park gave birth this month to their first litter. According to the SDZ, a baby pocket mouse reaches sexual maturity in about 41 days and carries out a pregnancy term in roughly 23 days.
That makes it possible for the pocket mice to be born and then give birth within the same breeding season.
It’s the fourth year that the San Diego Zoo Institute for Conservation Research have bred this California-native species, officials said. Fifteen litters of the Pacific pocket mouse species have been born, for a total of about 54 pups. In fact, there may be even more, as some of the just-born pups that have not yet left their nests were not counted.
Officials say even more pregnant females are expected to have pups, further increasing the birth rate of Pacific pocket mice, before the breeding season ends in October.
