Every February, the staff of the Pacific Pocket Mouse (PPM) Conservation Breeding Facility and some wonderful volunteers prepare our facility for the start of a new breeding season.

During the months of October through January, or the “off season,” males and females are housed in different rooms in the facility as they hunker down for a quiet couple of months, but as the mice begin to become more active, it is time to move them back together to start another breeding season. As the females and males start to become reproductive, we here at the facility start getting ready for our nocturnal lives. Since the mice are only active at night, so are we!

Even though the program has been successful in its breeding for 5 years now, and has honed its practices and techniques, breeding these mice is never an easy task.

The Pacific pocket mouse is a solitary animal, and even a receptive female can be notoriously aggressive.

Also, pairing a female in estrus with a male, does not guarantee a successful mating. Running a successful mating season is due largely to science, but a little bit of the work is an art! Choosing the pairings involves not only genetic compatibility programs, and researching past breeding notes, but also a knowledge of our captive population’s “personalities.”

As we ended March, we were excited to have our first two litters of the season! Since these little mice like to keep us on our toes, one mother gave birth a day early while the other went two days late, although both were safely in the normal range of the 22-26 day gestation period.

It’s always a very exciting way to start your shift by seeing healthy, tiny pink pups in a nest of white fluff.

We currently have four other potentially pregnant females, and will find out in the next few days how many more mice we will be adding to our population. Considering the facility’s success thus far, I’d say we have a very busy season ahead of us!