27th Annual Meeting and Symposium of the
Desert Tortoise Council, March 22-24, 2002
Abstracts

Habitat Use By Desert Tortoises at the Florence Military Reservation, Pinal County, Arizona

J. Daren Riedle, Roy C. Averill-Murray, and Darren K. Bolen
Nongame Branch, 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 gently sloping to nearly flat alluvial slopes in the north and more rugged terrain with deeply incised washes to the south. Along the banks of the washes, cavities are eroded into the calcium carbonate (caliche) soils. 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 14 tortoises 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. Tortoises found in the vicinity of boulder-strewn hillsides do use burrows within the boulder piles, in addition to caliche caves. Tortoise movements within the training areas are primarily constrained to a minimal area along the washes. Mean home range size for all tortoises was 15.5 ha. Mean home range for males (20.9 ha) was twice as large as for females (10.1 ha). Monitoring efforts will continue through 2002.