Reptiles
Pygmy Short-Horned Lizard
Phrynosoma douglasii · also called pygmy short-horned lizards
High on a rocky mountain slope in the northwestern United States, well above the warmer lowlands most horned lizards depend on, a pygmy short-horned lizard basks briefly before giving birth to fully formed live young rather than risking eggs in the cool ground.
Overview
The pygmy short-horned lizard, Phrynosoma douglasii, is a small, cold-tolerant reptile native to mountain and high-plateau habitat across a range of the northwestern United States. Its unusual tolerance for cool, high-elevation conditions, live-bearing reproductive strategy, and relatively recent recognition as a species distinct from the greater short-horned lizard make it one of the more cold-adapted members of the horned lizard group.
A horned lizard built for the mountains, not the desert
While most horned lizards are creatures of warm desert flats, the pygmy short-horned lizard has adapted to a cooler, higher existence, trading egg-laying for live birth to cope with a much shorter mountain growing season.
Status
Least Concern — present across suitable mountain and high-plateau habitat within its range in the northwestern United States.
Pygmy Short-Horned Lizard: common questions
Why does the pygmy short-horned lizard give birth to live young?
This species gives birth to live young rather than laying eggs, an adaptation that suits the shorter growing season and cooler conditions of its higher-elevation mountain range, since eggs laid in the ground would have less reliable warmth and time to develop compared with young carried and developed inside the female.
How is the pygmy short-horned lizard different from other horned lizards?
This species tolerates cooler, higher-elevation conditions than almost any other horned lizard species, allowing it to occupy mountain and high-plateau habitat unsuitable for many of its warmer-climate relatives, and it was only recognised as a species distinct from the more widespread greater short-horned lizard after further study.
How can you identify a pygmy short-horned lizard?
Look for a small body with shorter, less pronounced spines than several other horned lizard relatives, combined with a mottled grey, brown, or reddish pattern that blends well with the rocky, sparsely vegetated mountain and high-plateau ground it occupies.
Where does the pygmy short-horned lizard live?
This species is native to mountain and high-plateau habitat across a range of the northwestern United States, tolerating cooler conditions than most other horned lizard species thanks in part to its live-bearing reproductive strategy.