Northern Tree Lizard

Urosaurus ornatus wrighti

Northern Tree Lizard

Distribution in Wyoming

 

 

 

 

 

 

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The distribution of the Northern Tree Lizard runs from the tri-border area of Wyoming, Colorado, and Utah south through Arizona and New Mexico to southwestern Texas and into Mexico. It is a peripheral species in Wyoming restricted to a south-­central corridor in Sweetwater County, from the border with Colorado and Utah north to Rock Springs and Green River. It inhabits the canyon, juniper woodland, and sagebrush communities of the high desert where it prefers the large rock surfaces (vertical or horizontal) associated with outcrops, boulders, and cliffs—it is not an arboreal or tree living lizard as the name suggests. It often moves across the surface of the rock in a series of short, uneven and choppy or jittery movements. This lizard is a diurnal insectivore, active from late April through September, and feeds primarily on ants, spiders, flies, wasps, and moths.

Northern Tree Lizard Northern Tree Lizard

They are small thin lizards, at or just under 2 inches SVL. They have a long slender tail. Their skin is loose fitting as evidenced by the pair of wrinkles along the lateral margin of the body and the gular folds on the neck. They have a pattern of black fishnet or wavy crossbars set against a rusty-brown to slightly pinkish background. Males have a pair of prominent blue or turquoise patches along the sides of the abdomen; these patches are faint or lacking in females. Both sexes have a single, centered throat patch which may be blue, green, or a yellowish orange. Blue-orange throated males are more aggressive and show dominance over males with yellow throat patches.

Northern Tree Lizard Northern Tree Lizard

Characteristic of the species is the wide assortment of scale types and sizes which form a jumbled and chaotic pattern over the body. The dorsal surface is covered with small granular scales with a unique pattern running midline down the back. The scales of the center line are small and granular and are delimited on either side by a row of 3-4 scales; these border scales are larger, irregularly shaped, weakly keeled, and overlapping. The lance shaped scales on the anterior or leading margins of the legs are overlapping and keeled; those on the rear of the legs are small and granular. The belly scales are smooth, non-overlapping, and diamond or polygonal shaped.

Northern Tree Lizard Northern Tree Lizard

Males employ whole-body lifts (push-ups involving all four legs) to entice females or to warn off males that have intruded into their territory. Females usually lay two clutches (occasionally three) of 3-10 eggs during May and June (and July if a 3rd clutch). About two weeks after mating, the eggs are deposited in a shallow chamber and covered with sand or loose debris. Hatchlings begin to appear in late July and August. Sexual maturity is reached in the second year.