programs Natural Resources

Desert Grassland Habitat Assessment

Background


Two species considered for listing under the Endangered Species Act – the desert massasauga (Sistrurus catenatus edwardsii) and the spot-tailed earless lizard (Holbrookia lacerata) – are among the diverse species of West and South Texas grasslands. Both have been the subject of Texas Comptroller of Public Accounts (CPA)-funded research and have proven to be difficult to find, study and define.

These species have overlapping habitat with a historic range stretching from the coastal grasslands of South Texas to the scrub desert of West Texas. The massasauga, which is a nocturnal rattlesnake, and the spot-tailed earless lizard (STEL) have proven not only to be challenging for professional herpetologists to find, but recent genetics studies have also shown the original classification may be incorrect. The desert massasauga may not be separate from the western massasauga,1 and the spot-tailed earless lizard is likely two subspecies.2

Research Description

In 2018, the CPA identified the need to integrate ongoing STEL research with a larger assessment of habitat quality and quantity throughout the current and historic range of both species. The goal is to understand the status of the species by understanding the status of the habitat it depends on, both currently and historically.

Under contract with the CPA, researchers at Texas Tech University will compile satellite imagery to produce a 1-meter-resolution map of habitat types and land use patterns. They will then conduct widespread land cover surveys to check both the vegetation and habitat identified by the satellite and see what habitat the species actually use.

Upon completion of a validated habitat map, researchers will utilize the new tool to assess hypotheses concerning potential threats. The map will be analyzed for landscape-level habitat configuration, fragmentation and connectivity to identify high-value habitat areas. To isolate patterns in human land use change, researchers will compare the distribution of vegetation types and land use across three periods (1940, 1985, 2018) at study sites representative of the species’ ranges in Texas.

Deliverables Due at Contract End, March 15, 2022

  • Habitat map for STEL and desert massasauga in West and South Texas
  • Final report and landscape-level analysis to include
    • Changes in landscape-level habitat configuration, fragmentation and connectivity
    • Landscape changes due to anthropogenic and environmental disturbance, invasive species and conservation efforts

Why This Research Matters

Agriculture and oil and gas development drive land use change in South and West Texas. If the U.S. Fish and Wildlife Service determines this land use change threatens one or both species, current science lacks the information needed to determine what can be done to maximize conservation efforts and minimize economic impacts. If successful, the habitat map by Texas Tech will help fill this knowledge gap.


  • 1Texas Comptroller of Public Accounts, Final Report: Integrated Conservation Biology of the Desert (Sistrurus catenatus edwardsii) and Western Massasauga (S. c. tergeminus) at the Species and Population Level: Combining Ecological Niche Modeling with Genetic and Radio-Tracking Data, by John S. Placyk, Jr., Josh A. Banta, Richard A. Seigel, Marsha G. Williams, Mitch Barazowski, Steven R. Hein, Grace Herrington, and Neil B. Ford (Austin, Texas, January 4, 2017). (Consultant’s report.) Request the report.
  • 2Texas Comptroller of Public Accounts, Final Report: Collaborative Research on the Natural History of the Enigmatic Spot-tailed Earless Lizard (Holbrookia lacerata) in Texas, by Travis J. LaDuc, Brad D. Wolaver, Jon Paul Pierre, C. Michael Duran, Benjamin J. Labay, Wade A. Ryberg, Toby J. Hibbits, Corey E. Roelke, Matthew K. Fujita, Ian M. Wright, Gautam Surya, Cody J. Shank, Paul Holloway, John R. Andrews, Svetlana A. Ikonnikova, and Guinevere McDaid (Austin, Texas, May 7, 2018). (Consultant’s report.) View the report.