29th Annual Meeting and Symposium of the
Desert Tortoise Council, February 20-23, 2004
Abstracts

Home Range and Movements of Sonoran Desert Tortoises At A Long-term Study Site

Clayton L. Lutz*, Roy C. Averill-Murray, and J. Daren Riedle
Arizona Game and Fish Department, Nongame and Endangered Wildlife Program 2222 West Greenway Road, Phoenix, AZ 85023

A population of Sonoran desert tortoises at Sugarloaf Mountain in the Tonto National Forest has been the subject of an ongoing long-term reproductive ecology project. From 1996 to present, we have collected weekly locations on telemetered tortoises. To date, we have marked 135 tortoises at the site and recorded 8016 tortoise locations. Historically, Minimum Convex Polygons (MCP's) had been used to delineate individual tortoises home ranges. We are using kernel analysis, a probability density estimation approach to determining home range, to determine core areas and potential movement patterns of telemetered tortoises. Preliminary analysis shows that some males make seasonal movements from their hibernacula to areas where known females occur, while other males reside within the home range of several females and so do not engage in these seasonal movements. The availability of adequate shelter sites, primarily for hibernation, could be a causal factor for these forays undertaken by some males. Results from these preliminary analyses will be discussed during the presentation.