Habitat use of the Texas Alligator Lizard in Central Texas

Authors: Corey Fielder, Wade Ryberg, Danielle Walkup, Jared Holmes, Toby Hibbitts

Texas alligator lizards (Gerrhonotus infernalis) are regionally distributed from Central Texas into adjacent north-eastern Mexico and, apart from field observations, there are few published ecological studies. We utilised radiotelemetry data to assess seasonal macro- and microhabitat as well as arboreal habitat use for G. infernalis at two sites at Bamberger Ranch Preserve, Blanco County, Texas. We gathered habitat data from 54 lizards between May 2021 and June 2022, resulting in 859 and 339 points for the macro- and microhabitat analysis, respectively. Macrohabitats used varied by season, with more being occupied during the summer and fall while fewer were occupied during the winter and spring, but resource selection ratios indicated oak/hardwood rocky slope forests were important across all seasons. Microhabitat models indicated G. infernalis selects for structural microhabitat (woody plant and debris), rocky refuge, canopy cover, and slope (angle) of hill while avoiding more open areas devoid of structural habitat. In terms of arboreal habitat, G. infernalis primarily sought out dense vegetative and woody debris consisting of thin branches and high canopy cover throughout the year. Tree use by G. infernalis was random at one site but the other site showed non-random use, with lizards preferring Ashe juniper (Juniperus ashei) trees. This use of complex structural habitat provides G. infernalis with seasonal needs for foraging, thermoregulating, and avoiding predators. These findings provide new insights into the ecology of this species and will now allow us to compare the ecological traits of Central Texas populations to those occurring in other regions of their distribution.

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