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last updated 2/8/08
Phrynosoma cornutum is the Texas State Reptile. This species occurs mainly in the midwestern and southern United States as well as some parts of northern Mexico, but also extends westward through New Mexico and into south eastern Arizona. In 1967, Texas legislature passed laws preventing collection, exportation and sale of Phrynosoma cornutum from the state. But just prior to this legislation, hundreds of thousands of Horned Lizards were exported (dead and alive) from Texas every summer to tourists, curiosity seekers, and would-be pet owners, ultimately leading to the death of the lizards. As of today, THL populations in Texas and other midwestern stats continue to decline. Due to reduced grazing and discontinued agricultural use in Arizona populations are considered stable or increasing. Their range in Arizona covers hundreds of square miles. This area has a low human population.
The Texas Horned Lizard is about 2½ to 5" from snout to vent, with an overall length of 7 to 7½ inches. It is flat-bodied with large crown of spines on the head, of which the two center spines are the longest. There are two rows of fringe scales on each side. Their belly scales are keeled, and dark lines radiate from their eyes. They typically have a white or light colored strip down the center of their back.
P cornutum inhabits open country which may be from dry, hard pan with sparse brush, to loose, soil grasslands supporting cactus, mesquite, and other low sparse brush. Usually loose sand if it is available, as THLs often bury themselves. They have been observed during the summer months laying motionless during the night under black brush or other low bushes and using the blending of their colors to camouflage their resting place. They are also known to climb into the lower branches of bushes to spend the warm summer nights. Cornutum habitat is subject to summer thunder showers, which are thought to contribute significantly to their biology. The moisture comes during their mating period in early summer. Texas HLs are found from sea level up to 6,000ft.
Phrynosoma cornutum are oviparious. They may deposit up to forty or more eggs, which are laid in a burrow by the female, from the months of May to July. The young will typically hatch within six weeks. Neonates usually measure about 1¼".
Diurnal, mostly subsists on ants as a primary food
source, however small amounts of moths, beetles, and other insects
are relished as well. THLs, when frightened, may puff up, and squirt blood out of the corner of the eye as a defense against enemies. Blood squirting is generally reserved for canine threats, but it is sometimes used against perceived human threats as well. Texas Horned Lizards will go into hibernation around late September to October depending upon weather and usually do not come out until March or April. In Arizona their height of activity tends to occur in June.
In the wild, the main diet of Cornutum includes: roughly 69% harvester ants, with the remainder mostly being a mixture of termites, isopods, beetles, and grubs. Ants of the Pogonomyrmex barbatus species are the primary harvester ant preyed on by P cornutum. Feeding ususally occurs in the mornings after basking brings the body temperature up, and again in the late evening about sundown.
From central Kansas, southwestern Missouri, and the southeastern corner of Colorado throughout most of Oklahoma and Texas (including coastal barrier islands), the southeastern half of New Mexico and the southeastern corner of Arizona to the Mexican states of Sonora, Chihuahua, Durango, Nuevo Leon, Coahuila, Tamaulipas, and Zacatecas. Isolated populations do exist in Alabama. These lizards have also been inadvertantly introduced in Florida and South Carolina, where they seem to be doing quite well.
Texas Horned Lizards are listed as threatened in Texas and Oklahoma.
Populations have declined dramatically in both of these states. Cornutum have all but disappeared in the eastern and central portions of their range in Texas due to human disturbances, such as the conversion of habitat to agriculture and urban centers, and also due to the spread of non-native fire ants which are displacing the lizards native food ant.
In Arizona they have been observed to thrive right in the very small towns with populations below a few hundred people. This is probably because the land is not generally disturbed or changed from its natural state for the most part in these regions.
P cornutum have shown to do well in captivity if provided their natural diet and conditions. Captive breeding projects have been successful, but repatriation efforts have so far been largely unsuccessful. Exotic populations of P. cornutum in several states is itself evidence that repatriation efforts can succeed. It seems to be a matter of understanding the requirements for repatriation and should eventually be a successful endeavor. One of the problems of repatiration is in locating suitable habitat that is not encroached or invaded by exotic ant species.
Several of the members at phrynosoma.org have been successful in captive breeding and raising or P cornutum young. In the future we would like to work with the scientific community to help repatriate this species back into their native habitat.