Eastern Zebra-tailed Lizard, Callisaurus draconoides ventralis

Eastern Zebra-tailed Lizard, Callisaurus draconoides ventralis. Photographs courtesy of Dr. Tom Bartol, Carlsbad, California, taken within the Organ Pipe Cactus National Monument in Southern Arizona, March 2018.

Eastern Zebra-tailed Lizard, Callisaurus draconoides ventralis. Photograph taken within a residential community in the greater Alamos area, Alamos, Sonora, March 2010. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

Note: The Eastern Zebra-tailed Lizard, Callisaurus draconoides ventralis, is an understudied subspecies of the Zebra-tailed Lizard, Callisaurus draconoides. Due to lack of available information on this subspecies, this entry will describe the species in its entirety. However, the Eastern Zebra-tailed Lizard may demonstrate unique traits that are not found in other subspecies.

The Zebra-tailed Lizard is a member of the Phrynosomatidae family of North American Spiny Lizards, which includes the Zebra-Tailed, Earless, Fringe-Toed, Spiny, Tree, Side-Blotched and Horned Lizards. The Phrynsomatidae Family consists of more than one hundred-twenty members placed in nine genera. There is only one species in the Callisaurus genus of which there are nine subspecies. They are are referred to in Mexico as Lagartija Cachora.

Zebra-tailed Lizards are moderately-sized with a slightly dorsoventrally compressed body and tail. Their tail extends longer than their body length and is widened anteriorly. They have visible ear openings and a countersunk lower jaw. Their legs are long and their scales are small and granular. The scales on their upper lip are strongly keeled. Their dorsum is light brown in color with light spots and paired dark blotches, which are often more distinct in females. As with other lizard species, their coloring becomes darker during lower temperatures and lighter during very high temperatures. They have dark crossbars, or bands, on their tail that become very distinct on their white ventral side. It is this black and white zebra-like pattern that gives this species its name. Pale yellow and orange coloring marks their sides, and the center of their throat often has a pink or orange spot. Sexual dimorphism is displayed with males possessing two dark bars on the sides of their mid belly. Additionally, males develop a patch of blue-green coloring on their sides during the breeding season. Dark belly markings are faint or absent on females. They measure between 6.0 cm (2.5 inches) and 10.0 cm (3.9 inches) in snout to vent length. Including their tail, they measure up to 23 cm (8.1 inches) in length.

Zebra-tailed Lizards are diurnal and are often seen basking on rocks during the afternoon, even in extremely hot temperatures. To avoid the heat of the substrate, they may stand alternately on two legs in the shade or climb into bushes. During the late fall and cold months of the winter, they hibernate underground. They are one of the first species to emerge in the spring, and they remain active throughout the summer. Zebra-tailed Lizards construct burrows, typically beneath shrubs, that are used for shelter and to hide from predators. Their countersunk lower jaw makes it easier for them to burrow into loose or sandy soil. While they are often solitary, Zebra-tailed Lizards are sometimes found in populations of varying sizes. Their home range varies depending upon age and sexual maturity. Adult males have large home ranges that tend to overlap those of several females. Territories are defended using physical gestures such as push-up displays and head nods.

Zebra-tailed Lizards are polygynous, and the bond formed between a male and a female may be strong or weak. Strong bonds result in greater territory defense and longer duration of the male-female relationship. Once a bond is formed, the two court briefly and copulate. It is beneficial for males to mate with as many females as possible, as it typically results in higher rank or hierarchical standing. During breeding season, males attract mates by perching themselves in an exposed area and performing a series of head bobs and push-ups, similar to their territorial defense displays. Their breeding season begins in May and extends into August. Gestation lasts between forty-eight and sixty-two days. Females lay their eggs in a sheltered and humid environment to prevent desiccation. They lay between two to six eggs (average of four eggs per clutch), with each egg measuring approximately 15 mm in length. During greater than average rainfall, females may lay up to five clutches in one year. Hatchlings are born with an “egg-tooth” on their nose that is used to slice through the egg, and is lost shortly after hatching. The young are smaller but otherwise very similar in appearance to adults. Offspring are precocial and little parental care is provided. Only pre-hatching parental investment occurs by the female and includes choosing an appropriate nesting site, laying eggs in a moist environment, covering or sheltering eggs, and defending the area around the nest until hatching. Juveniles reach sexual maturity after approximately two years. While they can live up to four years in the wild, adults rarely live more than three years.

Zebra-tailed Lizards use tail displays in both social communication and predator-prey signaling. When a potential predator is detected, they vibrate their tail while raising the distal end, exposing their vivid black and white stripes. They may also curl their tail over their back and move it in a side-to-side motion to distract predators. Tail displays are observed most often in open areas with little to no cover available. This tactic concentrates a predator’s attention on the tail, which can grow back if broken off. When threatened, they hide in a nearby bush or sprint away, running in a zig-zag pattern for up to 50 m (164 feet). They are considered to be one of the fastest desert lizards and can run up to 7 meters per second (16 mph). Their  diet primarily consists of arthropods such as beetles, grasshoppers, crickets, flies, ants, bees, wasps, moths, and spiders. Occasionally, they consume other smaller lizards and the fruiting heads of plants. They are often observed jumping several body-lengths off the ground to capture flying insects. In turn, they are preyed upon by snakes, larger lizards, predatory birds, foxes, and coyotes.

Zebra-tailed Lizards are found at elevations that extends from sea level to approximately 1,520 m (5,000 feet). They are typically found in sparsely vegetated desert areas on open sandy washes, dunes, floodplains, beaches, or desert pavement. At higher elevations, they sometimes inhabit rocky, relatively shady, leaf litter substrates.

Zebra-tailed Lizards are similar to both Earless Lizards (genera Cophosaurus and Holbrookia and Fringe-toed Lizards (genus Uma. All genera have small granular scales on their dorsal side and folds of skin across their throats. In Zebra-tailed Lizards, these scales vary in size and texture across their bodies. Unlike Earless Lizards, both Zebra-tailed and Fringe-toed Lizards possess external ear openings. Belly markings also differ among these groups. Fringe-toed Lizards have a single large blotch, while both Earless and Zebra-tailed Lizards have two crescent-shaped markings.

From a conservation perspective, the Zebra-tailed Lizard is considered to be of Least Concern due to their wide distribution and presumed large population size. No major threats have been identified for this species. Local populations may be detrimentally affected by habitat destruction and degradation as a result of conversion of land for human uses, such as agriculture and commercial development.