Meeting Abstract

P2.44  Tuesday, Jan. 5  Impacts of fire on thermoregulatory opportunities for desert tortoise: Use of operative temperature models SNYDER, S.J.*; TRACY, C.R.; University of Nevada, Reno ssnyder@biodiversity.unr.edu

Recently, fires in the Mojave Desert have burned extensive portions of habitat used by the threatened desert tortoise (Gopherus agassizii). Burned landscapes may challenge the thermoregulatory capabilities of tortoises, since they rely on underground burrows and vegetative cover as buffers from extremes in desert thermal environments. By reducing the availability or altering the physical properties of above ground vegetative cover, fires may indirectly result in behavioral and/or physiological changes to tortoises living in burned-unburned habitat interfaces. To assess the differences in temperatures available to tortoises, operative temperature models were placed in various microhabitats available to desert tortoises in burned and unburned areas. Operative temperature models were constructed from copper mixing bowls similar in dimension to a desert tortoise and painted to match the integrated spectral absorptance of a tortoise’s shell for daytime solar radiation. These models were relatively easy to build and replicate allowing operative temperatures in many microhabitats to be simultaneously recorded for comparison. Measurement of model temperature was achieved using an internally mounted iButton. Thus, models could be distributed throughout the landscape, untethered to a data logger, and could be moved easily among locations. Temperatures gathered from the physical operative temperature models closely matched mathematically calculated operative temperatures, validating their use for evaluating the thermal quality of burned and unburned habitat with respect to tortoises.