San Antonio Zoo – Horned Lizard Reintroduction Project
San Antonio Zoo’s Center for Conservation and Research seeks to reintroduce large numbers of captive-reared horned lizards to areas of their native range in Central Texas where they have been extirpated. The iconic Texas horned lizard (Phrynosoma cornutum) is the state reptile of Texas and was once abundant throughout a large range. They prefer arid to semi-arid areas with sparse plant cover and loose sand or loamy soils; their diet consists mostly of native harvester ants and other insects. Horned lizard populations have declined or disappeared in many places in Texas since the late 1960s due to factors including fragmentation and habitat loss, introduction of exotic grasses, red imported fire ants, and pesticide use.
Many Texans have fond memories of the Texas horned lizard (aka “horny toad”) from their childhoods and many landowners and resource managers have pled for the return of this species to its former range. Fortunately, sufficient areas of suitable habitat exist where lizards may be reintroduced, and many landowners are engaged in landscape management practices that benefit the Texas horned lizard.
The project began in early 2017 with a mission focusing on the re-establishment of viable horned lizard populations, returning this species to the landscape as part of a healthy native ecosystem and for the enjoyment of present and future generations. San Antonio Zoo Center for Conservation and Research staff are involved in all aspects of the project, from lizard husbandry to site evaluation. A unique component of this project is utilizing trained horned lizard detection dogs from Chiron K9 to locate the cryptic lizards in the field. Dog handlers will travel with their trained companions to release sites to monitor post-release success and assist in ongoing conservation research.
San Antonio Zoo’s long-term goal is to develop replicable methodologies to share with other conservation entities, create awareness of native biodiversity and opportunities for its preservation, and to return this species to areas where they were once abundant. The project will initially focus on counties in Central and South-Central Texas to include Bexar, Bandera, Comal, Hays, Blanco, Kerr, and Kendall counties with properties covering about 250 acres of contiguous high-quality horned lizard habitat.
Landowners who are interested in restoring horned lizards to the property enact habitat management practices that help restore the landscape to a more natural state. Wildlife species that naturally occur in the project region will be positively impacted by the enhanced native habitat. Landscape restoration practices for horned lizards also benefit bobwhite quail, another iconic Texas species, due to their similar habitat needs. Bodies of water within and surrounding these properties will be positively impacted to some extent – native plants encourage groundwater infiltration and reduce erosion. Proper ecosystem function will be restored through habitat management processes that restore the landscape to a natural state.
Many Texans born prior to 1970 and who lived in the urban corridor from Houston to Dallas have fond memories of abundant horned lizards. Children and grandchildren of that cohort are largely unfamiliar with the species and very few have ever seen a living horned lizard. This includes residents of rural areas as well as those who live(d) in urban and suburban landscapes. Most releases are expected to take place on large tracts of private land and San Antonio Zoo is working with corporate landowners, city and county entities, and preserves that provide access to the public. For people who are fond of the horned lizards but may not meet the program’s habitat requirements can learn how to manage their properties so that horned lizards may naturally establish on their property after nearby reintroductions. Additionally, members of the public are welcomed to become trained lizard detection dog handlers through Chiron K9, further engaging the community with local conservation efforts.