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

Wildfires are known to kill individual desert tortoises, but effects of fires on tortoise populations are largely unstudied. The Mother’s Day Fire (8 May 1994) burned approximately 138 hectares (340 acres) of desert tortoise habitat on the Rincon Management Unit of Saguaro National Park. On standardized surveys conducted in June 1994, we found six live and seven dead tortoises, five of which were apparently killed by the fire. We estimate this fire-caused mortality to be approximately 12% of the adult tortoise population that inhabited the area prior to the burn, a catastrophic loss estimated at six times the expected annualized mortality rate for a sustaining population of this long-lived species. All live desert tortoises appeared to be healthy and continue to be monitored and compared to tortoises in an adjacent unburned site. Fires also may have longer lasting effects on tortoises due to habitat alteration. Approximately one square kilometer plots (0.6 x 0.6 miles) in burned and nearby unburned habitats were intensively surveyed for tortoises during summer 1996. Using radiotelemetry in 1997, we tracked tortoises in burned and unburned areas.