Four Pacific pocket mice have been born at the San Diego Zoo Safari Park, according to San Diego Zoo Global. It’s the first litter this season.
The Pacific pocket mouse, thought to have gone extinct in the 1980s, was rediscovered in 1993, according to researchers. There are only three wild populations of the rare mice, all in Southern California.
In 2012, the zoo and the U.S. Fish and Wildlife Service started a breeding program to save the endangered mouse.
The mother of the latest litter, which was born April 1, was the first Pacific Pocket mouse born in the breeding program, according to the zoo.
Another litter is expected this weekend.
The breeding facility is equipped with air conditioners and humidifiers to mimic coastal weather and large skylights so the nocturnal creatures know when the sun is rising and setting.
According to scientists, a Pacific pocket mouse has a gestation period of 23 days and can reach sexual maturity in less than two weeks. This means these newborn pups could themselves reproduce this breeding season.