One of my companions along Bridge Mountain-North Peak route.
Red Rocks, Nevada. May 2008.

Western Fence Lizards (Sceloporus occidentalis biseriatus) are very common in Red Rocks. Their color ranges from light gray to black. They are often also called "Blue-bellies" or "Swifts".
Interesting fact: It has been discovered that when ticks caring Lyme disease feed on the western fence lizard the bacteria that cause Lyme disease are killed. In areas where western fence lizards occur the incidents of Lyme disease are lower.