Western fence lizard
The Western Fence Lizard (Sceloporus occidentalis) is a common lizard of California and the surrounding area. It is also known as the Blue-belly. Not all fence lizards have a "blue belly". Smaller sized, immature fence lizards have aquamarine colored bellies until they mature. Though they do not have colored bellies, they are still referred to as a 'blue belly'.
Taxonomy for the Western fence lizard has been under much debate. S. occidentalis belong in the order Squamata (snakes and lizards) and the suborder Iguania. The family in which they belong to is still under scrutiny. The family Phrynosomatidae, along with 7 other families, used to be included in the single family Iguanidae, until Frost and Etheridge's (1989) analysis of iguanian systematics suggested that the family be split up. Some literature, however, still places the Phrynosomatids in Iguanidae.
six subspecies are 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 measure 5.7-8.9 cm (snout-vent length) and a total length of about 21 cm. They are brown to black in color (the brown may be sandy or greenish), but their most distinguishing characteristic is their bright blue belly and the ventral side of the limbs are yellow. These lizards also have a blue patch on their throat. 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.
Many other lizards have similar bright blue coloring. The Eastern Fence Lizard, S. undulatus, instead of having one large pouch on its throat, has two small patches. The Sagebrush Lizard, S. graciosus, lacks yellow limbs and has smaller dorsal scales. S. occidentalis also resembles the Side-blotched Lizard, Uta stansburiana. However, the axilla of U. stansburiana usually has a black spot behind it and they have a complete gular fold .
Distribution and habitat
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.
The Western fence lizard enjoys a variety of habitat. It is found in grassland, broken chaparral, sagebrush, woodland, coniferous forest, even farmland, and occupy elevations from sea level up to 10,800 ft. They generally avoid the harsh desert.
They are commonly seen sunning on paths, rocks, and fence posts, and other high places. This behavior makes them an easy target to predation by snakes, birds, and even some mammals, like shrews. They protect themselves by employing their fast reflexes, which is common in many other lizards.
The Western fence lizard eats spiders and insects.
Like most other lizards, S. occidentalis goes through a period of hibernacula during the winter. The length of their hibernacula and when they emerge varies depending on climate. During the mating season, adult males will defend a home range.
Western fence lizards mate in the spring, and do not breed until the spring of their second year. Females lay 1-3 clutches of 3-17 eggs (usually 8) between April and July. The eggs hatch in August.
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.
- ^ a b "Sceloporus occidentalis". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=173875. Retrieved 6 February 2006.
- ^ Family Phrynosomatidae from Animal Diversity Web
- ^ a b c d e f g Stebbins, Robert C. "A Field Guide to Western Reptiles and Amphibians." 3rd ed. Peterson Field Guides, 2003
- ^ a b c Sceloporus occidentalis from Idaho Museum of Natural History
- ^ a b c d Sceloporus occidentalis from San Diego Natural History Museum
- ^ C. Michael Hogan (2008) "Western fence lizard (Sceloporus occidentalis)", Globaltwitcher, ed. Nicklas Stromberg 
- ^ Lizards that fight Lyme disease from the California Academy of Sciences
|Wikimedia Commons has media related to: Western Fence Lizard|