Declines have been linked to loss of habitat, over-collection by the pet trade, and the accidental introduction of the imported fire ant. Concerns over the depletion of this treasured resource led the Texas State Legislature to provide protection for the species in 1967. The Texas horned lizard was most recently bestowed the honor as the Texas State Reptile in 1992. Despite low numbers in east and central Texas, the Texas horned lizard is still locally common in portions of the Rio Grande Plains of south Texas, the Rolling and High Plains of northwest Texas and the Trans Pecos of far west Texas. In response to dwindling horned lizard numbers and the need to better understand horned lizard ecology, the Chaparral Wildlife Management Area began monitoring its horned lizard population in 1991.
Monitoring revolves around a mark-recapture study.
Recapture data allows for the estimation of population numbers. Adult horned lizards attain an average size of 5 inches, with females being somewhat larger than males. Although horned lizards continually grow throughout their lives, growth drastically slows once they reach maturity. Intervals between captures of individuals indicate that horned lizards can live to at least seven years of age in the wild. More research is needed to fully understand all aspects of horned lizard ecology.