Patterns of Burrow Use by Desert Tortoises: Gender Differences and Seasonal Trends

Knowledge of burrow use and movement patterns, and how they are influenced by social interactions in desert tortoises, is critical to understanding habitat use in this threatened species. I examined sex differences and seasonal variation in burrow use by desert tortoises. Twentyeight free-ranging tortoises were fitted with radio transmitters and were regularly located from June-October 1992. Location and behavior of radio-tagged tortoises were recorded and occupied shelters were marked. Patterns of burrow use and co-occupancy differed between the sexes and corresponded to the reproductive cycle. Most observations were of tortoises inhabiting shelters singly. During the nesting season in June, female tortoises moved among shelters more than did males. During the mating season in August and September, males changed shelters more frequently than did females, and male-female co-occupancy was commonly observed. Consideration of burrow use patterns and associated social behavior may improve population density estimates, success of relocation management, and understanding of the epidemiology of upper respiratory tract disease.