Although individuality in alarm calls has been reported for many ground-dwelling sciurids, the degree to which the vocal identity encoded in alarm calls is stable with time has been studied only for a single sciurid species. Thus, no comparable data are available. We examined the retention of the vocal keys to individual identity after hibernation in a natural colony of yellow ground squirrels (Spermophilus fulvus), long-lived, obligate-hibernating rodents that maintain stable social groups for years. We recorded alarm calls in 2 subsequent years, separated by hibernation, from 22 individually marked animals. All individuals could be distinguished with high probability by their alarm calls within a year. However, only 6 of the 22 animals kept their alarm calls stable after hibernation. Sex, age, year of data collection, and the distance that individuals moved between years did not have significant effects on the retention of a stable alarm call structure after hibernation. Given the low proportion of individuals with stable alarm calls, vocal identity cannot be the only modality sufficient to secure the recovery of personalized social relationships after hibernation in the yellow ground squirrel.