Twenty-Third Annual Meeting and Symposium of the
Desert Tortoise Council, April 3-5, 1998
Abstracts

Radio tagged tortoises were located at three sites with steep slopes (Barstow Marine Corps Logistics Base [MCLB], Fort Irwin National Training Center [FINTC]), and Marine Corps Air Ground Combat Center-Lava [MCAGCC-L]) on a weekly schedule, to investigate the physical features of areas in which these animals are found. A total of 546 locations were made from March 28th to September 17th of 1997. These locations consist primarily of full season records for 29 individuals (14 male, 15 female), and include 140 recognizable cover sites. Animals were found to utilize slopes from 0º to 33º. Significant variation was found among sites, and among tortoises within sites. No significant difference was found between sexes. The three sites were found to differ in the percent composition of five substrate particle size classes. The percent of substrate particles of cobble and boulder size ranged from 0% and 0% respectively, for locations at both MCLB and FINTC, to as high as 70% and 40% for locations at MCAGCC-L. Additionally, the direction in which the cover site opened was recorded for all permanent/semi-permanent cover sites. This direction was found to be dependent on the aspect of the slope. The location of the animal (above or below ground), and a suit of environmental variables, for the purpose of estimating G₀, were also recorded. The predictive capacity of these variables will be discussed.