Colorado, often known for its snow-capped peaks, presents a surprisingly diverse landscape that supports approximately twenty native lizard species. Despite the state’s reputation for cold, high-altitude geography, these reptiles thrive in warm, arid regions and lower elevations. As ectotherms, lizards rely entirely on external heat sources to regulate their body temperature. The abundant Colorado sunshine and varied microhabitats, including plains, canyons, and scrublands, provide the necessary conditions for their survival.
Identifying Colorado’s Native Lizard Species
Colorado’s lizard population possesses unique physical traits that aid in identification. One frequently observed group is the whiptails, such as the Six-Lined Racerunner, characterized by a sleek body and a long, slender, whip-like tail. These lizards are typically dark brown or black with six to eight prominent light stripes. Males often exhibit bright green or turquoise coloring on their bellies, while the Western Whiptail features a more web-like pattern of gray-brown coloring with dark bars or spots.
Horned Lizards are another distinctive group, known for their short, flat, and wide bodies. The Greater Short-Horned Lizard is identifiable by the crown of short, stubby spines, or “horns,” encircling the back of its head. Their coloration is usually a beige, tan, or reddish base, speckled with white and large brown blotches that provide excellent camouflage. Skinks, including the Many-lined Skink, possess a smoother, shinier scale texture and reduced necks, giving them a streamlined, almost serpentine appearance.
The Collared Lizards are among the largest and most colorful species, easily recognized by the two dark bands that resemble a collar around their neck. Males of the Eastern Collared Lizard are particularly vibrant, displaying brilliant green bodies and bright yellow heads, a clear example of sexual dimorphism. In contrast, the Spiny Lizards, such as the Plateau Fence Lizard, have rough, overlapping, and pointed scales that give them a noticeably spiny texture. Males in this group often feature striking blue patches on their throats and abdomens, which are used in territorial displays.
Geographic Distribution and Preferred Habitats
The presence of lizards in Colorado is a direct reflection of the state’s varied topography, with their distribution largely restricted by elevation. Most species are found below 8,000 feet, as high-altitude mountains present temperatures too cold for survival. Lizards concentrate in the warmer, lower-lying regions of the Eastern Plains and the Western Slope. They require environments that offer ample sunlight for basking and suitable shelter for regulating body temperature and escaping predators.
The Western Slope, featuring arid shrublands, canyons, and pinyon-juniper woodlands, hosts species like the Longnose Leopard Lizard and the Ornate Tree Lizard. Rocky habitats, including cliffs and talus slopes, are favored because they absorb and retain heat, providing warm basking surfaces. The Eastern Plains and southeastern parts of Colorado feature extensive tracts of sandy soil and prairie grasslands. This terrain is home to specialized species like the Common Lesser Earless Lizard, which has adapted to burrow into the loose earth for refuge.
Observing Lizards and Their Ecological Role
Lizards are active during the day, and their daily schedule is dictated by the sun’s warmth. They spend the early morning hours basking on rocks or pavement to raise their body temperature for hunting. This reliance on external heat means they become sluggish on overcast days. During the winter, they enter a state of brumation, a form of reptile hibernation.
These reptiles are primarily insectivores, acting as important natural pest control agents in their ecosystems. Their diet consists of a wide array of small invertebrates, including beetles, spiders, termites, and scorpions. Larger species, such as the Collared Lizard and Longnose Leopard Lizard, are opportunistic predators that will consume smaller lizards. This role as both predator and prey makes them a significant part of the food web, where they are hunted by birds of prey, snakes, and small mammals.
To observe lizards responsibly, search for them in sunny, rocky areas during the warmest parts of the day. Lizards are harmless to humans, and observers should maintain a respectful distance to avoid disturbing their natural behavior. Their presence and health serve as a reliable bioindicator, signaling the overall well-being of the local environment.