Thermal ecology of reintroduced and native Texas horned lizards (phrynosoma cornutum)

Ryan, Patrick

Publication

Thermal ecology of reintroduced and native Texas horned lizards (phrynosoma cornutum)

Ryan, Patrick

Date

2022-04-21

Abstract

Due to habitat loss the Texas horned lizard (THL) (Phrynosoma cornutum) population has declined across its historic range. To date, reintroduction attempts for the species have been unsuccessful, calling into question the suitability of the habitat. Texas horned lizards require suitable thermal habitat to meet their thermoregulatory needs, because of this, understanding the thermal habitat requirements of THLs is important. The objective of this study was to determine thermal habitat preferences of reintroduced THLs at Mason Mountain WMA compared to a nearby natural population of THLs on the White Ranch. We also compare the thermal conditions of different microhabitats between the two sites. To do this, we used thermal dataloggers to record the temperatures in different microhabitats throughout the day at each study site, then compared how much of the time these data loggers were within the lizard’s optimal and critical temperature range. The ground temperature selection by the lizards versus random points on the ground were assessed to see what factors affected selection the most such as, study site, time of day, and microhabitat. It was found that the two sites did not differ from each other in terms of microhabitat thermal quality and for the temperature and microhabitat measurements taken for the lizards. Similar to other studies on THLs, vegetative cover seems to play an important role in providing quality thermal habitat and thermal refugia. These findings suggest that habitat management should focus on maintaining vegetative cover for THLs and more work should be done to look at the impacts of microhabitat configuration on overall habitat quality.