The young and the earless: understanding growth and lifespan of the Tamaulipan Spot-tailed Earless Lizard

Hibbitts, Toby J.

Natural Resources Institute

Texas A&M University

College Station, Texas USA

Biodiversity Research and Teaching Collections

Department of Ecology and Conservation Biology

Texas A&M University

College Station, Texas USA

toby.hibbitts@ag.tamu.edu

Steffen, Kathryn J.

Fielder, Corey M.

Natural Resources Institute

Texas A&M University

College Station, Texas USA

Owen, Jacob D.

Air Force Civil Engineering Center

Randolph, Texas USA

Johnson, Darren

Laughlin Air Force Base

Del Rio, Texas USA

Ryberg, Wade A

Danielle K. Walkup Natural Resources Institute

Texas A&M University

College Station, Texas USA

The Tamaulipan Spot-tailed Earless Lizard (Holbrookia subcaudalis) is a poorly understood species. It is distributed across southern Texas, south of the Balcones Escarpment into adjacent Mexico east of the Sierra Madre Oriental but seems to have never been common. Its restricted distribution and apparent population declines led the US Fish and Wildlife Service to consider this species for federal listing. Here we study one of the few known robust populations at Laughlin Air Force Base, Del Rio, Texas. We conducted a mark recapture study to estimate population size as well as other typical population parameters; however, a lack of recaptures did not allow us to make the desired population estimates. In 2022-2024 we increased our survey effort to determine the lack of between season recaptures. With the increased effort and the 2-3-fold increase in lizard captures, we have been able to better understand the growth rate, age at maturity, and likely average lifespan of a robust population of Tamaulipan Spot-tailed Earless Lizards.