The Texas Horned Lizard (Phrynosoma cornutum), often called the “horned toad,” is a reptile known for its distinctive, flattened body and a crown of prominent horns. This species once thrived across the American Southwest and Plains states, including Oklahoma, making it an iconic part of the region’s natural heritage. The lizard relies on camouflage and its thorny exterior for defense, perfectly suited to the sandy, open habitats it prefers.
Current Conservation Status in Oklahoma
The Texas Horned Lizard is not listed as threatened or endangered at the federal level or by the State of Oklahoma. However, the Oklahoma Department of Wildlife Conservation (ODWC) classifies the species as a Tier I Species of Greatest Conservation Need (SGCN) and a Species of Special Concern. This classification indicates that while the species is not facing immediate extinction, its populations are declining significantly and require active conservation management to prevent future listing.
The state offers legal protection through a year-round closed season on its collection, in effect since 1992. This regulation makes it illegal to collect, possess, harm, or sell Texas Horned Lizards without specific ODWC permission. This protection focuses on the individual animal, but it does not extend to the lizard’s habitat, a significant distinction in conservation law. Despite these protections, the lizard has become increasingly rare in the central and eastern parts of the state, though it remains common in the western third of Oklahoma.
Primary Factors Driving Population Decline
The decline of the Texas Horned Lizard population is attributed to environmental and human-caused pressures. A major mechanism of decline is the fragmentation and loss of their preferred habitat: native grasslands and open areas with loose, sandy, or loamy soils. The conversion of these native prairies into agricultural fields, non-native pastures, or urban developments removes the specific environmental conditions the species needs to survive.
Pesticide Use and Food Loss
The widespread use of pesticides and insecticides indirectly starves the lizards. The Texas Horned Lizard is a specialized feeder, relying almost entirely on harvester ants for its diet. When chemical treatments are applied to landscapes, the harvester ant colonies are decimated, removing the lizard’s primary food source and making the area uninhabitable.
Invasive Species
A major threat comes from the invasive imported red fire ant (Solenopsis invicta). These aggressive invaders compete directly with the native harvester ants, further reducing the lizard’s food supply. Imported fire ants also pose a direct threat by preying on young lizards and attacking the eggs in their underground nests.
State and Federal Protection Measures
Conservation efforts in Oklahoma focus on research, monitoring, and citizen involvement. The ODWC implemented a citizen science project encouraging the public to report sightings of the Texas Horned Lizard. These submissions help biologists track the species’ current distribution and identify remnant populations, which is crucial since range and population data are often limited.
Research and Monitoring
Research is underway in partnership with institutions like the University of Oklahoma and the Oklahoma City Zoo. Projects at locations such as Tinker and Altus Air Force Bases involve tracking lizards with radio transmitters and PIT tags to understand their movements and population health. The Oklahoma City Zoo’s Lizard Lab focuses on research that may lead to future captive breeding and reintroduction efforts, including studying factors like gut bacteria.
Funding and Landowner Support
The ODWC promotes conservation funding through the sale of Texas Horned Lizard specialty license plates, with proceeds directly supporting nongame conservation efforts. Landowners are encouraged to support the species by minimizing pesticide use and maintaining open, native grassland habitats that support healthy harvester ant populations.