Home Range and Habitat Associations of the Spot-Tailed Earless Lizard

Walkup, Danielle K. 

Department of Wildlife and Fisheries Sciences

Texas A&M University

College Station, TX

dkwalkup@tamu.edu

Frizzell, Shelby

Neuharth, Dalton 

Johnson, Timothy

Ryberg, Wade A.

Natural Resources Institute

Texas A&M University 

College Station, TX

Toby J. Hibbitts

Biodiversity Research & Teaching Collection 

Natural Resources Institute

Texas A&M University

College Station, TX

The Spot-tailed Earless Lizard (Holbrookia lacerata) is thought to be declining throughout its range and was petitioned for federal listing in 2010. Currently, a listing decision is scheduled for 2020 and there is a need for basic biological data on movements, home ranges, and habitat preferences for the Spot-tailed Earless Lizard. From May to July 2017, driving and time-constrained walking surveys were conducted for the two subspecies of this lizard, the Northern Spot-tailed Earless Lizard (H. l. lacerata) in Crockett County, TX and the Southern Spot-tailed Earless Lizard (H. l. subcaudalis) in Val Verde County, TX. Thirty-three adult Spot-tailed Earless Lizards were fit with radio transmitters. Radioed lizards were relocated three times daily at two-hour intervals. On average, males of both the Southern and Northern Spot-tailed Earless Lizards moved longer distances than females, both between fixes (i.e. step lengths) and overall (i.e. total step length). Nineteen lizards had at least 25 fixes, which provided enough data to estimate the home range of those individuals using Minimum Convex Polygon (MCP) and Kernel Density Estimation (KDE). There were no significant sex differences for MCP, 50% KDE, or 95% KDE. This baseline data will help us to better understand the movements and home ranges of the Spot-tailed Earless Lizard, allowing us to make better recommendations on conservation and management strategies for the two subspecies.