Six-lined Racerunner

These whiptail lizards are voracious predators and can be found in abundance across eastern Colorado.

Six-lined Racerunner, Tony Hober, CPW

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About This Species

The six-lined racerunner is an aggressive whiptail lizard that can be found across eastern Colorado to the margins of the mountains. They are beautifully striped with colors ranging from muted to brilliant, with males sometimes sporting a blue belly.

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Physical Characteristics

Body long and slender; upper side with small granular scales; belly with larger rectangular scales; three pale stripes along each side of back, plus a stripe along the middle of the back sometimes divided into two stripes; no light spots or bars in dark fields between stripes; neck and shoulders of adults often with bright-greenish wash; stripes may not contrast sharply with dark areas on shoulders; scales on undersurface of base of front legs not enlarged; maximum size about 27 cm (10.6 inches) total length and 8.8 cm (3.5 inches) snout-vent length. 

Mature Male 

Belly pale blue. 

Mature Female

Belly whitish. 

Hatchling

Tail bright blue; light stripes contrast sharply with dark areas on shoulders.

Range

Throughout eastern Colorado to the margins of the mountains. Common.

Habitat

Plains grassland (including rocky out-croppings and roadsides), sandhills, sandy or gravelly banks and floodplains of streams, grassy openings among ponderosa pines in the foothills, and open areas among rocks at the base of the mountains. Unvegetated or sparsely vegetated openings are required; the lizards spend nearly all of their active time moving about on the ground. During periods of inactivity, racerunners hide beneath rocks, logs, and various debris, or underground; commonly digs own burrow under object or in sandy soil.

Reproduction

Females produce 1-2 clutches of eggs from June to early August. Hatchlings emerge in August and September.

Reptile
Aspidoscelis (Cnemidophorus) sexlineata