Reptiles
Yarrow's Spiny Lizard
Sceloporus jarrovii · also called Yarrow's spiny lizards
High in an isolated Arizona sky-island mountain range, a Yarrow’s spiny lizard basks on a sun-warmed rock at an elevation cool enough that laying eggs in the ground would be a genuine gamble, a problem it has solved by giving birth to live young instead.
Overview
Yarrow’s spiny lizard, Sceloporus jarrovii, is a stocky, live-bearing lizard native to mountain forest habitat across isolated sky-island ranges of southeastern Arizona, New Mexico, and adjacent Mexico. Its unusual live-bearing reproduction among spiny lizards, distinctive dark collar marking, and preference for high-elevation oak-pine woodland make it one of the more ecologically specialised lizards of the American Southwest.
Built for the cold end of the mountain
While most spiny lizard relatives lay eggs in warm lowland soil, Yarrow’s spiny lizard has adapted to a cooler, higher-elevation existence by carrying its young until they’re ready to be born fully formed.
Status
Least Concern — widespread and common across suitable mountain forest habitat throughout its sky-island range.
Yarrow's Spiny Lizard: common questions
Why does Yarrow's spiny lizard give birth to live young instead of laying eggs?
This live-bearing reproductive strategy is well suited to the cooler, higher-elevation mountain habitat the species occupies, since carrying developing young inside the body lets the mother regulate their temperature more effectively than eggs left in cool mountain soil could manage on their own.
How can you identify Yarrow's spiny lizard?
Look for a bold, dark collar-like marking across the shoulder area, a helpful field mark that distinguishes this species from several other spiny lizards, combined with its association with higher-elevation oak-pine woodland habitat.
Where does Yarrow's spiny lizard live?
This species occupies isolated sky-island mountain ranges across southeastern Arizona, New Mexico, and adjacent Mexico, typically at notably higher elevations than many of its spiny lizard relatives, favouring oak-pine woodland habitat.
Does Yarrow's spiny lizard show any social behaviour?
Yes, this species displays a degree of social organisation and tends to return to familiar basking and shelter sites, a behavioural pattern that has been studied in some detail among populations of this lizard.