TXST researchers lead conservation efforts for Brazos water snake

The Brazos water snake is found in only a small part of Texas, where changes to rivers, reservoirs, and shorelines can affect much of the species’ habitat. Its habitat is shrinking and becoming fragmented into smaller, disconnected areas. Drought, declining populations, local population losses, and disease intensify the pressure.

David Rodriguez, Ph.D., professor of biology at Texas State University, is leading a conservation effort to establish a breeding program for Brazos water snakes and ultimately release them into suitable habitats, with support from a Texas Parks and Wildlife Department grant.

The project builds on nearly two decades of research by Rodriguez, TXST students, technicians, postdoctoral researchers, faculty members, and conservation partners. Since 2006, they have documented the snake’s populations, habitat, genetics, and disease and created the foundation needed to design and test the conservation effort. Their research has also shown that populations in different locations have genetic differences, so losing one local population could mean losing part of the species’ genetic diversity.

“Receiving this support is especially meaningful because it allows us to move from documenting declines and disease to testing a direct conservation response,” Rodriguez said. “This grant gives us the opportunity to turn that knowledge into action in partnership with the Houston Zoo and the Texas Parks and Wildlife Department.”

The project aims to strengthen existing populations, restore populations where they have declined, and improve the species’ long-term survival chances. 

The Houston Zoo manages a protected breeding population of snakes collected from four areas. The colony could provide healthy, genetically diverse offspring for future releases. The Texas Comptroller of Public Accounts and Brazos River Authority are also contributing their expertise to the project.

Researchers will use genetic testing and health assessments to select breeding pairs and screen snakes for disease. They will identify release sites with suitable habitat, nearby populations, and connections to other populations, while accounting for human disturbance.

“We have spent the last three years sampling, tagging, and tracking snakes across over a dozen candidate release sites. Every spring and fall we assess the snakes for signs of disease, conduct habitat assessments, and run tests to examine genetic diversity and disease prevalence,” said Analisa Shields-Estrada, Ph.D., a postdoctoral researcher co-leading the project. “This data allows us to assess population health, calculate population estimates, and advise on land management decisions, all critical components to determining future release sites.”

Plans call for releasing five to 10 young snakes at each of four sites annually. Spring and fall monitoring will track survival, movement, habitat use, reproduction, and whether released snakes establish populations. The findings will guide future releases and could inform conservation efforts for other threatened reptiles and amphibians.

The project could also serve as a model for conserving threatened reptiles, amphibians, and fish with small, fragmented populations. At TXST, it will provide training in disease ecology, molecular genetics, conservation, and pathogen detection. Those skills can support careers in wildlife, agriculture, and human health.

“The long-term value of this project is that it will replace a one-size-fits-all approach with a tested, data-driven framework for recovery,” Rodriguez said.

Ultimately, the team hopes to keep the Brazos water snake moving through the waters it calls home, while preparing future scientists to protect other species.