Plateau Spotted Whiptails like rocky hillsides, canyon bottoms

Sometimes an animal's common name can be confusing. One such case involves a lizard found in West Texas but bears a name that for years was confusing to me. How could an animal that does not reside on a plateau in Texas have a name that indicates it does? Then it occurred to me: The plateau in question is not an eco-region here in Texas, but rather the plateau that separates the Sierra Madres from each other in central Mexico. This particular lizard is common throughout this plateau, so the name really does apply!

The Plateau Spotted Whiptail (Aspidoscelis scalaris) is one of 10 species of “racerunners” that live in Texas. It can be observed in the Big Bend region, basically from Van Horn southward along the Rio Grande eastward to Sanderson. Outside of this great state, it occurs in the Mexican states of Chihuahua, Coahuila, Durango, Nuevo Leon and northern San Luis Potosi. This wary lizard's preferred habitat appears to be arid rocky hillsides and canyon bottoms that have sparse vegetation.

The Plateau Spotted Whiptail is an elongated reptile covered with small, granular scales of equal size along its back and sides. It is one of the larger whiptail species in Texas, with adult males reaching a total length of just over one foot, although the average is about 9 inches.

The back is adorned with six or seven light tan stripes that run lengthwise from the neck to the hips. Numerous dark spots appear in random order in between these light stripes, giving this animal the common name.

The long tail, which can be up to 65 percent of the animal’s total length, is a rust color that extends onto the posterior third of the body in mature specimens, a great diagnostic feature for identification in the field. The belly scales are much larger and plate-like in appearance, and in females are light-colored. Males have dark blue-black mottling on the belly and orange chins during breeding season.

Plateau Spotted Whiptails, like other lizard species, are “cold-blooded,” or ectothermic, meaning they do not generate heat from the inside of their body, as mammals and birds do, but are dependent on outside sources for heating and cooling. They are active throughout the day from March to November, and unlike many other reptile species, the high metabolism of this lizard enables it to be observed during the hottest part of the summer afternoons.

This species is an omnivorous dietary generalist, feeding on animal matter as well as plant material. It feeds primarily on small beetles, ants, grasshoppers and other arthropods, but it occasionally feeds on certain leaves and flowering blossoms such as the dandelion.

The Plateau Spotted Whiptail is oviparous, which means it lays eggs. After emerging from the winter-long brumation period (reptiles do not hibernate in the true sense of the word), males search out females to mate. After mating, the female lays a small clutch of eggs (between two and five) in moisture-retaining soil. Older, large females can lay two to three clutches of eggs per summer. After about two months of incubation, the delicate, 5-inch-long young emerge prepared to fend for and care for themselves. 

These lizards are nervous and can be quite wary. They are constantly on the move, foraging for food in the ground cover and loose soil. Occasionally they will stop to bask in between meal items, but their metabolism is such that they will begin to forage within minutes of stopping.

Their movement is based on short bursts of speed, rarely more than a few feet at a time unless they feel threatened. Look to observe this speedy lizard in and around city parks and nature trails.

Michael Price is owner of Wild About Texas, an educational company that specializes in venomous animal safety training, environmental consultations and ecotourism. Contact him at wildabouttexas@gmail.com.