Phrynosoma cornutum is listed as a threatened species in Texas and Okalahoma. The numbers of the Texas Horned Lizard have declined for several reasons: the collection of the lizard as a pet, the invasion of the imported fire ant, Solenopsis invicta, and loss of habitat (Donaldson, et al 1994). The change in land use has taken away homes from the lizards, and the use of pesticides on the harvester ants has depleted their main food source (Donaldson, et al 1994). Texas Parks and Wildlife along with other conservation groups are studying aspects of the Texas Horned Lizard as to protect it from any further negative human impact.
IUCN Red List of Threatened Species: least concern
The Texas Horned Lizard eats mainly Harvester ants, Pogonomyrmex spp., but will also eat grasshoppers, isopods, beetles and beetle larvae. In order to obtain enough energy, adult Texas Horned Lizards must forage from several colonies of Harvester ants. The Texas Horned Lizards' daily activities are planned around the times of highest ant activity. (Donaldson, et al 1994)
The distribution of the Texas Horned Lizard ranges from Kansas to Northern Mexico and from Arizona to Louisiana (Bockstanz 1998).
The Texas Horned Lizard lives mainly in sandy areas where it often inhabits abandoned animal burrows (Bockstanz 1998). The habitat of the Texas Horned Lizard is usually in close proximity to the nests of harvester ants (Seymour 1996).
Biomes: Desert, grasslands, prairies, scrubland (Bartlett and Bartlett 1999)
Terrestrial Biomes: desert or dune ; savanna or grassland
The Texas Horned Lizard has a dorsolaterally flattened, toad-like body (Seymour and Royo 1996). Due to their unusual body shape body and short legs, they have been mistaken for an amphibian, hence the name "Texas Horned Toad."
There are spines located on the head, along the sides of the body and down the tail (Bockstanz 1998). These spines are modified epidermal scales. At the back of the head, there are two elongated spines that look like horns (Seymour and Royo 1996). There are also spines located along the dorsal surface of the lizard (Bockstanz 1998).
The ventral surface of the lizard is either gray or tan (Seymour and Royo 1996). The dorsal surface of the lizard is tan or gray with white and red or yellow highlights (Bockstanz 1998). There is a pattern of dark spots on the dorsal surface of the lizard, which correspond to the location of the dorsal spines (Bockstanz 1998).
The length of an average Texas Horned Lizard is 69mm snout-vent length (Munger 1986), however the upper boundary for males is 94mm and for females it is 114mm (Munger 1984).
The breeding season begins in late April and continues into July (Seymour 1996). These lizards are oviparous, and will lay their eggs in moist, sandy areas (Bartlett 1999). The eggs have a flexible, white shell, which measures 1-and1/2 inches in diameter (Seymour 1996). The incubation period for the eggs is 45-55 days (Bartlett 1999). The hatchlings are approximately 1.25 inches long, and are relatively smooth. However, the hatchlings do have the spines around their heads. There is no evidence of parental care for the young, so they must find food and defend themselves against predators immediately after hatching. The age of reproductive maturity is not known, however they are full-grown adults at three years of age (Seymour 1996).
