Western fence lizard

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Western Fence Lizard

Subspecies taylori

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Sauria
Family:	Phrynosomatidae
Genus:	Sceloporus
Species:	S. occidentalis

Binomial name

Sceloporus occidentalis
Baird and Girard, 1852

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

Although California is the heart of the range of this lizard, it is also found in eastern and southwest Oregon, southwest Idaho, Nevada, New Mexico, western Utah, and northwestern Baja California, and 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 metres, but it is not found in the desert.

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

Subspecies bocourtii

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 colour (the brown may be sandy or greenish), but adult males have iridescent blue lateral patches on their flanks, and their entire bodies may be flecked with blue. The blue colour 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 behaviour makes them vulnerable to predation by 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.