Thermal ecology of Texas horned lizards (Phrynosoma cornutum) in small Texas towns

Abstract

Texas horned lizards (Phrynosoma cornutum) have disappeared from many areas in Texas probably in large part due to loss of suitable habitat. Populations of this lizard still persist in the towns of Kenedy and Karnes City in southern Texas. This species has continued to decline and disappear from these towns. We hypothesize this may in part be due to the degradation of the thermal landscape for these lizards caused by the removal of important microhabitats. We determined the selected body temperature (Tsel) was 35.7 ± 0.33 ºC at our field sites and body temperatures (Tb) was 33.6 ± 0.3 ºC. Overall, our sites had high average thermal quality (de = 4.92), but thermal quality differed by microhabitat with vegetation having the highest thermal quality followed by dirt and open microhabitats. These findings support that vegetation is an important microhabitat for thermoregulating and removing vegetation would degrade the thermal landscape.