28th Annual Meeting and Symposium of the
Desert Tortoise Council, February 21-23, 2003
Abstracts

Habitat Use by Desert Tortoises at the Florence Military Reservation, Pinal County, Arizona: A 2002 Update

J. Daren Riedle, Darren K. Bolen, and Roy C. Averill-Murray
Arizona Game and Fish Department 2221 W. Greenway Rd. Phoenix, AZ 85023

The Florence Military Reservation (FMR) is a 10,421-ha site in Pinal County, AZ, located approximately 80 km southeast of Phoenix. The Arizona Army National Guard uses FMR as a military training site, utilizing 14, 15 x 1000-m training areas (firing boxes) for ground support and artillery exercises. FMR contains flat alluvial slopes in the north and more rugged terrain with deeply incised washes to the south. In 2000, a three-year radio telemetry study was undertaken to determine habitat use and movement patterns of desert tortoises at FMR, relative to land use for military purposes. Up to 18 tortoises (7 males, 8 females, and 3 juveniles) have been monitored to date at FMR. Sonoran desert tortoises typically live on steep desert mountain slopes in rocky burrows. At FMR, tortoises confine most activity to the incised washes and caliche caves. When not in washes, tortoises primarily use pallets under bursage clumps and woodrat middens as cover. Tortoise movements within the training areas are primarily constrained to a minimal area along the washes. Mean home range size for all tortoises (n=18) was 18.28 ha. Mean home range size for males (28.47 ha), was larger than for females (10.79 ha), and juveniles (14.49 ha). In 2002, 7 females were sampled by use of X-radiography to determine clutch size and nesting sites. Four females produced eggs with a mean clutch size of 5. Females nested in caliche caves and soil burrows. Monitoring and reproductive studies will continue through 2003.