| western fence lizard (blue-belly) | |
|---|---|
| Subspecies taylori | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Iguania |
| Family: | Phrynosomatidae |
| Genus: | Sceloporus |
| Species: | S. occidentalis |
| Binomial name | |
| Sceloporus occidentalis Baird and Girard, 1852 |
|
The western fence lizard (Sceloporus occidentalis) is a common lizard of California and the surrounding area. Because the ventral abdomen of an adult is characteristically blue, it is also known as the blue-belly. Immature western fence lizards have aquamarine-colored bellies.
It is a member of the genus Sceloporus, and therefore is a spiny lizard.[1]
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Taxonomy for the western fence lizard has been under much debate. S. occidentalis belongs in the order Squamata (snakes and lizards) and the suborder Iguania. The family in which it belongs is still under scrutiny. The family Phrynosomatidae, along with seven other families, used to be included in the single family Iguanidae, until Frost and Etheridge's (1989) analysis of iguanian systematics suggested the family be divided.[2] Some literature, however, still places the phrynosomatids in Iguanidae.
Six subspecies are recognized, as follows:
Some authors have raised the island fence lizard to specific rank, Sceloporus becki. However, recent work in molecular systematics has suggested there are four clades and 11 genetically separable populations, and the subspecies will probably have to be redefined.[1]
Western fence lizards measure 5.7-8.9 cm (snout-vent length)[3] and a total length of about 21 cm.[4] They are brown to black in color (the brown may be sandy or greenish), but their most distinguishing characteristic is their bright blue belly. The ventral sides of the limbs are yellow.[5] These lizards also have blue patches on their throats. This bright coloration is faint or absent in both females and juveniles. The scales of S. occidentalis are sharply keeled, and between the interparietal and rear of thighs, there are 35-57 scales.[3]
Many other lizards have similar bright blue coloring. The eastern fence lizard, S. undulatus, instead of having one large patch on its throat, has two small patches.[3] The sagebrush lizard, S. graciosus, lacks yellow limbs and has smaller dorsal scales.[3] S. occidentalis also resembles the side-blotched lizard, Uta stansburiana. However, the axilla of U. stansburiana usually has a black spot behind it and it has a complete gular fold.[3]
Although California is the heart of the range of this lizard, it is also found in eastern and southwest Oregon, as well as in the Columbia River Gorge, southwest Idaho, Nevada, western Utah, and northwestern Baja California, and some of the islands off the coast of both California and Baja California.[6]
The western fence lizard occupies a variety of habitats. It is found in grassland, broken chaparral, sagebrush, woodland, coniferous forest, and farmland, and occupies elevations from sea level to 10,800 ft.[3] They generally avoid the harsh desert.
As of now, the western fence lizard is listed as unprotected, and no conservation restrictions apply.[5][5]
These lizards are commonly seen sunning on paths, rocks, and fence posts, and other high places, which makes them an easy target for predation by snakes, birds, and even some mammals, such as shrews. They protect themselves by employing their fast reflexes, which is common in many other lizards.[5]
The western fence lizard eats spiders and insects.
Like most other lizards, S. occidentalis goes through a period of hibernation during the winter. The length of time and when they emerge varies depending on climate. During the mating season, adult males will defend a home range.[4]
Western fence lizards mate in the spring, and do not breed until the spring of their second year. Females lay one to three clutches of three to 17 eggs (usually eight) between April and July. The eggs hatch in August.[3][4]
Studies have shown that Lyme disease is lower in areas where the lizards occur. When ticks carrying Lyme disease feed on these lizards' blood (which they commonly do, especially around their ears), a protein in their blood kills the bacterium that causes Lyme disease. The ticks blood is therefore cleansed and no longer carries Lyme disease.[7]