Overview
The Short-horned Lizard (Phrynosoma hernandesi), historically known as the Greater Short-horned Lizard, is a fascinating, cold-adapted reptile native to the windswept plains and mountain plateaus of western North America. Inhabiting elevations up to 3,000 meters—higher than any other horned lizard—it has evolved extraordinary adaptations to cold climates, including live birth (viviparity) rather than egg-laying.
Biology and Physical Characteristics
The Short-horned Lizard has a broad, flattened, pancake-like body fringed by a single row of pointed lateral scales. Its head is adorned with a distinctive crown of short, blunt, stubby horns that project upward and backward, giving it a spiky yet compact profile. The coloration is cryptic grey, yellowish-brown, or reddish-brown with dark, white-edged dorsal blotches that mirror the exact gravel and lichen-covered stones of its montane habitat.
Behavior and Ecology
A specialist predator of ants and small beetles, the Short-horned Lizard sits patiently near ant mounds, flicking out its sticky, mucus-covered tongue to snatch passing insects. Unlike southern desert horned lizards that lay eggs in warm sand, female Short-horned Lizards retain embryos internally to bask them in mountain sunshine, giving birth to 6 to 30 fully formed, self-sufficient live young in late summer.
Conservation and Human Impact
Assessed as Least Concern by the IUCN, the Short-horned Lizard remains widely distributed across vast tracts of public rangeland in the American West. However, extensive energy development, agricultural conversion of shortgrass prairies, and invasive cheatgrass degradation of sagebrush steppe present regional conservation challenges.
Interesting Factoid
Because high Rocky Mountain summers are too short and freezing for eggs to hatch in the soil, the mother Short-horned Lizard acts as a mobile solar incubator, giving birth to live baby lizards wrapped in translucent birth sacs.