Illinois supports a modest population of five native lizard species, despite the common perception that lizards are restricted to warmer climates. These reptiles are often overlooked due to their small size and secretive nature. They are a natural component of Illinois’s biodiversity, though they are not as widely distributed as common reptiles like turtles and snakes.
The Confirmed Species of Illinois Lizards
The five native species belong to two distinct lizard families: skinks and whiptails, plus one unique legless form. The Common Five-lined Skink (Plestiodon fasciatus) is a medium-sized lizard reaching up to eight and a half inches.
Juveniles are recognized by their glossy black body, five light stripes, and a striking bright blue tail, which fades as they mature. The Broad-headed Skink (Plestiodon laticeps) is the largest native lizard, sometimes approaching thirteen inches.
Adult males lose their juvenile stripes, developing a uniform olive-brown color and an enlarged, reddish-orange head during the breeding season. The smallest species is the Little Brown Skink (Scincella lateralis), which grows to about five and three-quarter inches.
This tiny skink is copper or golden-brown with a dark stripe along its sides, and it forages among the leaf litter. The Six-lined Racerunner (Aspidoscelis sexlineata) belongs to the whiptail family and is known for its incredible speed.
This slender lizard is dark-bodied with six prominent light stripes—yellow, white, or pale blue—extending from head to tail. Racerunners are typically six to nine and a half inches long and possess tiny, granular scales on their back.
The final native species is the Slender Glass Lizard (Ophisaurus attenuatus), a completely legless reptile that can reach forty-two inches. Its snake-like appearance is deceiving, as it is a true lizard distinguished by a flexible groove running along each side of its body. It is named for its extremely long, fragile tail, which easily breaks off as a defense mechanism against predators.
Where to Find Lizards in Illinois
The distribution of native lizards is concentrated in the southern and central portions of Illinois. This pattern results from the more favorable climate, which features longer warm seasons and milder winters compared to northern counties. Habitat availability also dictates where these reptiles establish stable populations.
Lizards thrive in microhabitats offering sun exposure, cover, and loose soil for burrowing and nesting. Sand prairies are particularly important, providing the open, sunny conditions favored by the Six-lined Racerunner and the Slender Glass Lizard. Populations also occur along major river corridors, such as the Mississippi and Illinois Rivers, where sand deposits and open floodplain habitats exist.
Skink species are more commonly found in wooded areas, utilizing the rocky bluffs and open woodlands of southern Illinois. Common Five-lined Skinks and Broad-headed Skinks are encountered near rotting logs, stumps, and under leaf litter for cover, nesting, and foraging. The Little Brown Skink is a ground dweller that spends most of its time hidden beneath the forest floor’s debris layer.
Distinguishing Skinks and Racerunners
Distinguishing native lizards often involves observing the appearance and behavior of the two main groups: skinks and racerunners. Skinks (Common Five-lined, Broad-headed, and Little Brown) are characterized by their remarkably smooth, shiny, overlapping scales, giving them a sleek appearance.
A key field marker for juvenile skinks is the bright blue tail, an adaptation that diverts a predator’s attention. Racerunners, such as the Six-lined Racerunner, have a drastically different texture, featuring small, granular scales on their back.
Their behavior is distinct; they are exceptionally fast and active foragers, often darting across open ground. This speed is a primary defense mechanism, contrasting with the skinks’ reliance on cover and tail-shedding ability.
The legless Slender Glass Lizard is often mistaken for a snake, but it possesses two distinct lizard features. Unlike snakes, this species has movable eyelids, allowing it to blink, and visible external ear openings on the sides of its head. These characteristics confirm its classification as a lizard, even without limbs.