One approach to combating the threat of invasive species replacing the native food sources of captive-bred endangered animals from conservation breeding and reintroduction programs is to expand the foraging options of these animals to include palatable invasive species. Utilizing the conservation breeding program for the endangered Pacific Pocket Mouse (Perognathus longimembris pacificus, PPM), we experimentally determined how seed origin, exposure during crucial developmental periods, and nutritional quality influence PPM’s willingness to consume invasive food types. Preferences were tested using the Cafeteria Method design and nutritional characteristics were determined with near infrared-reflectance spectroscopy. Captive-born PPM preferred commercial seeds, which contain higher levels of moisture and starch, to native and invasive seeds. However, exposure to invasive seeds during pre-weaning increased PPM’s willingness to forage for invasive seeds. This study, the first of its kind, has the potential to improve PPM reintroduction efforts and provides insights to other management programs facing similar concerns.