by Dr. Travis LaDuc, Curator of Herpetology, Department of Integrative Biology
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| (Photo: Ian Wright) |
The Spot-tailed Earless Lizard (Holbrookia lacerata) is a small (70 mm snout-vent length), enigmatic lizard historically found across much of the Edwards Plateau, parts of the Permian Basin in west Texas, and parts of the south Texas Plains [additionally, ~25% of the total range of the species is found in Mexico]. Following a 2008–2010 survey of Texas historical localities, we found the species at only 14 sites, mainly south and west of San Angelo. In 2011, the US Fish and Wildlife Service found that listing this species may be warranted; this listing decision is scheduled for fiscal year 2020. In an effort to provide the best available science that could inform this decision, the Texas Comptroller of Public Accounts (TCPA) has funded a group led by Dr. Travis LaDuc from the Biodiversity Center at The University of Texas at Austin, along with colleagues from the Bureau of Economic Geology (UT-Austin), and The Nature Conservancy. Work initiated in 2014 focused on surveys and modeling habitat and habitat fragmentation. Collaborators from Texas A&M University and The University of Texas at Arlington joined the group in 2015 and 2016 to expand field surveys and initiate genetic work.
Through three years of survey work, we have a better understanding of the current distribution of this lizard in the state. However, this understanding is tempered by the fact that, because 96% of land in the state is private, our surveys have been restricted to surveys along roads and right-of-ways, thus introducing strong sampling bias. This was an important first step in documenting lizard presence, but now our focus is trying to understand how lizards use their habitat on a fine scale. To accomplish this, we are using radio telemetry to track individual lizards 3–4 times a day. With repeated relocations, we can begin to understand home range sizes and tease apart differences in home range size between males and females during their active season (April–August). Additionally we are using mark-recapture methods to document presence, persistence, and movement of lizards in the landscape.
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| A student attempts to capture a lizard. (Photo: Travis LaDuc) |
This April, the Spring 2018 Field Herpetology class (BIO 369F), taught by Dr. LaDuc, visited a new potential Spot-tailed Earless Lizard site in Kimble County. Within 45 minutes, the class had found and collected two males. Because of their speed and wariness, lizards were collected using lizard nooses (collapsible fishing poles with fishing line fashioned into a noose) – no lizards were harmed during their capture! The lizards were measured, marked and returned to the site the following morning. The class also had the opportunity to radio track animals on an adjacent property and quickly became proficient at finding lizards! This was the second time LaDuc’s Field Herpetology class has found lizards at a new site, demonstrating the power of 15 sets of eyes are stronger than one!
To learn more about the Field Herpetology class, please visit this link: https://biodiversity.utexas.edu/academics/biology-field-courses