Microhabitat Selection by Texas Horned Lizards in Southern Texas

Abstract

The Texas horned lizard (Phrynosoma cornutum) has declined throughout its range. Understanding habitat selection by the Texas horned lizard is an important factor in its conservation. We examined daily and seasonal habitat requirements of Texas horned lizards and determined whether habitat selection differed among land management treatments in southern Texas. We used 5 study sites, each with a different burning and grazing treatment. Adult lizards caught in the study sites were fitted with backpacks carrying radiotransmitters and relocated daily. Habitat characteristics at radio locations and random points 10 m from the lizard were assessed using 50- × 20-cm quadrats. Relocations were made during 3 time intervals (morning, afternoon, evening) and 2 seasons (active, inactive). Horned lizards used bare ground and herbaceous vegetation similar to their availability in the morning and evening for thermoregulation and foraging purposes, but avoided bare ground in the afternoon. In the afternoons, lizards selected woody vegetation and litter as thermal refuges and cover from predators. Lizards also appeared less dependent on herbaceous vegetation and more dependent on woody vegetation and litter in the inactive season compared to the active season as a result of increased temperatures. We did not detect differences in habitat selection among land management treatments. Habitat management for Texas horned lizards should focus on creating a mosaic of bare ground, herbaceous vegetation, and woody vegetation in close proximity.