Effects of Ionizing Radiation on Survival, Longevity, and Reproduction in Free-Ranging Pocket Mice, Perognathus parvus

There was no significant difference between the responses of captive and free-ranging Great Basin pocket mice, Perognathus parvus, to ionizing radiation. The${\rm LD}_{50(30)}\pm {\rm SD}$values were 858 ± 27 rad and 834 ± 32 rad, respectively, and the slopes of both survival curves were parallel. Although some unconfined mice lived 3 years postirradiation, the median longevity was 12 months or less for all dose levels. Median longevity appeared to be inversely related to absorbed dose above the threshold exposure: 675 rad. Radiation-induced sterility was not evident in free-ranging males, but all irradiated females appeared to be permanently sterile in subsequent breeding seasons. Pocket mice were able to survive secondary effects including: swelling and eversion of cheek pockets; depilation; and a change in coat color from tan to white.