Western Fence Lizard

The Western Fence Lizard (Sceloporus occidentalis), also known as the Blue-belly or Swift, is a common spiny lizard found throughout California.

Although California is the heart of this lizard’s rang, it is also found in eastern Oregon, southwest Idaho, Nevada, western Utah, Southern California, and northwestern Baja California, as well as some of the islands off the coast of both California and Baja California. It is found in scrub and chaparral up to heights approaching 2000 meters, however it is not found in the desert.

The taxonomy of this species is currently under discussion: until recently, six subspecies were recognized, as follows:

• Island Fence Lizard, Sceloporus occidentalis becki
• San Joaquin Fence Lizard, Sceloporus occidentalis biseriatus
• Coast Range Fence Lizard, Sceloporus occidentalis bocourtii
• Great Basin Fence Lizard, Sceloporus occidentalis longipes
• Northwestern Fence Lizard, Sceloporus occidentalis occidentalis
• Sierra Fence Lizard, Sceloporus occidentalis taylori

Some authors have raised the Island Fence Lizard to specific rank. However, recent work in molecular systematics has suggested that there are four clades and 11 genetically separable populations, and the subspecies will probably have to be redefined.

Western Fence Lizards are about 8-10 cm long excluding their tail, and about 15 cm long with the tail included. They are brown to black in color, but adult males have iridescent blue lateral patches on their flanks, and their entire bodies may be flecked with blue. The blue color is much less noticeable in females and juveniles.

The Western Fence Lizard eats insects and spiders. They are commonly seen sunning themselves on paths and rocks, and this behavior makes them vulnerable to predators such as snakes and birds. The blue stomach of the male is used in a territorial display.

It is thought that the presence of Western Fence Lizards diminishes the danger of transmission of Lyme disease by ticks. The incidence of Lyme disease is lower in areas where the lizards occur, and it has been found that when ticks carrying Lyme disease feed on these lizards (which they commonly do, especially around their ears), the bacteria that cause the disease are killed.