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

Evaluating Trauma in Live Desert Tortoises: Wild vs. Domestic Canids A Preliminary Report

Andrea Demmon and Kristin H. Berry
U. S. Geological Survey, Western Ecological Research Center, 22835 Calle San Juan de Los Lagos, Moreno Valley, CA 92553

Desert tortoise (Gopherus agassizii) populations have declined for numerous reasons in recent decades. Trauma (defined as injury to the shell or soft tissues caused by impact or predation) from vehicles, predators, and domestic livestock have contributed to poor health and increased mortality rates in some areas. We developed a method of grading trauma to live desert tortoises using 35-mm slides and data sheets. We are retrospectively evaluating data sets from long-term permanent plots, health and disease studies, and miscellaneous research projects. The database will include site; date; tortoise identification, sex, and size; percentage of injury to each scute and limb; type of injury; potential source of injury; distance from towns and settlements; and many other attributes. Our objectives are to characterize the types of trauma affecting live tortoises by size, sex, and location, and ultimately to address critical recovery issues. One important recovery issue, identified in the Desert Tortoise Recovery Plan (U.S. Fish and Wildlife Service, 1994), is attack by domestic or feral dogs. Tortoise populations most likely to be affected are near towns and cities. With our developing database, we have taken a preliminary look at differences in trauma from wild vs. domestic canids. We present examples from a few sites in the Western Mojave Recovery unit, comparing sites near settlements (Sand Hill, Daggett, Lucerne Valley) with a remote site at Fort Irwin. In general, attacks by dogs differ from attacks by wild canids in the amount and type of scute removed and bone exposed, especially to the gular horn. In the few samples we have evaluated to date, tortoises at sites within 3 km of settlements or isolated houses show more severe damage to shells and limbs than tortoises at remote sites.