Home Range and Daily Activity of the Round-tailed Ground Squirrel, Spermophilus tereticaudus neglectus

Data on home range and daily activity were collected by direct observation of a population of marked round-tailed ground squirrels, Spermophilus tereticaudus neglectus, during the summer (1967 and 1968) in a Sonoran Desert Larrea zone in S-central Arizona. Summer daily activity of the squirrels was bimodal, with maximum activity in the early morning and late afternoon. Foraging was the primary activity and grooming and burrow excavation secondary. Squirrels often moved throughout their entire home ranges during their morning activity but seldom left the main burrow entrances during the afternoon activity when ambient temperatures peaked. Mean home range estimates of 0.74 acre for adults and 0.77 acre for juveniles were derived by the minimum area method and changed throughout the summer months. Food preferences (e.g., blooming chinchweed) caused resident squirrels to shift their ranges while juvenile squirrels gradually increased their ranges through the summer as they moved away from their home burrows. Of the 1968 resident squirrels, 68.5% had home ranges that were coincident in part with 1967 ranges.