The western fence lizard (sceloporus occidentalis), so named for its habit of climbing onto the tops of fence posts in early morning to warm up, measures about 5 inches long. It is larger than its close cousin the sage lizard. It is also known as a Blue-bellied lizard or blue-bellied swift, or just blue-belly, due to the prominent bright blue color along the sides of the mature male's abdomen. Six subspecies have been documented. This one has been named the Northwestern Fence Lizard (sceloporus occidentalis occidentalis).
Recent research has shown that when ticks infected with the Lyme disease feed on the lizard's blood, it destroys the disease's spirochetes carried by the ticks. Incidence of Lyme disease is found to be only 5 percent where the lizards live compared to 50 percent in areas where they are not found.