The western fence lizard (Sceloporus occidentalis) is a species of lizard native to Arizona, New Mexico, and California, as well as Idaho, Nevada, Oregon, Utah, Washington, and Northern Mexico. The species is widely found in its native range and is considered common, often being seen in yards, or as the name implies, on fences. As the ventral abdomen of an adult is characteristically blue, it is also known as the blue-belly. Two western fence lizards have been reported with duplicated or forked tails, presumably following an autotomy.[2]
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.[3] Most literature, however, still place the phrynosomatids in Iguanidae.
Male S. o. occidentalis displaying iridescent, bright turquoise and blue coloration.
Western fence lizards measure 5.7–8.9 centimetres or 2.2–3.5 inches (snout-vent length)[5] and a total length of about 21 centimetres (8.3in).[6] They are brown to black in color (the brown may be sandy or greenish) and have black stripes on their backs, but their most distinguishing characteristic is their bright blue bellies. The ventral sides of the limbs are yellow.[7] Male blue belly lizards also have blue patches on their throats. This bright coloration is faint or absent in both females and juveniles. In some populations the males also display iridescent, bright turquoise blue spots on the dorsal surface. The scales of S. occidentalis are sharply keeled, and between the interparietal and rear of thighs, there are 35–57 scales.[5]
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.[5] The sagebrush lizard, S. graciosus, lacks yellow limbs and has smaller dorsal scales.[5]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.[5]
A juvenile western fence lizard.
Distribution and habitat
Although California is the heart of the range of this lizard, it is also found in eastern and southwestern Oregon (some populations are found even north of Seattle, Washington), as well as in the Columbia River Gorge, southwestern Idaho, Nevada, western Utah, northwestern Baja California, New Mexico, Arizona, and some of the islands off the coast of both California and Baja California. There is also an isolated population in the Northwestern Tualatin Valley, around Henry Hagg Lake.[8]
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 10,800ft.[5] They generally avoid the harsh desert and are often found near water.
As of now, the western fence lizard is listed as unprotected, and no conservation restrictions apply.[7]
Adult male western fence lizard.
Urbanization
Habitat loss caused by urbanization has many effects on the western fence lizard. Lizards in an urbanized environment have evolved to have shorter limbs and toes. This is because of the change in surfaces that the lizards use. While before urbanization western fence lizards used mostly woody substances, after urbanization they used more man-made substances, a greater breadth of habitats and developed shorter limbs and toes.[9]
The habitat loss also causes a decrease in the number of scales. This is because of the urban heat island effect, increasing the temperature year round.[9] The increase in temperature causes an increase in scale size and a decrease in scale number as it decreases the number of living cells in-between the scales and lowers evaporative water loss and heat load.[10]
Behavior
The blue ventral side of the lizard, giving it the name "bright blue belly"
These lizards are diurnal, and are commonly seen basking on paths, rocks, and fence posts, and other suitable sunny locations.[7] They can change color from light grey or tan to nearly jet black for the purpose of thermoregulation while basking. S. occidentalis goes through a period of brumation 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.[6]
The western fence lizard primarily eats small invertebrates, but may consume any appropriately sized prey item.[11]
Reproduction
Western fence lizards mate in the spring, and do not breed until the spring of their second year. Females lay eggs under a flat surface by digging a nest at night. She lays one to three clutches of three to 17 eggs (usually eight) between April and July. The eggs hatch in August.[5][6]
Lyme disease
Western fence lizard with ticks
Studies have shown that cases of Lyme disease are rarer in areas where the lizards are found. When ticks carrying Lyme disease feed on these lizards' blood (which they commonly do, especially around their ears), a protein in the lizard's blood kills the bacterium in the tick that causes Lyme disease. The infection inside the ticks' gut is therefore cleared and the tick no longer carries Lyme disease.[12]
Related Research Articles
Spiny lizards is a common name for the genus Sceloporus in the family Phrynosomatidae. The genus is endemic to North America, with various species ranging from New York, to Washington, and one occurring as far south as northern Panama. The greatest diversity is found in Mexico. This genus includes some of the most commonly seen lizards in the United States. Other common names for lizards in this genus include fence lizards, scaly lizards, bunchgrass lizards, and swifts.
Side-blotched lizards are lizards of the genus Uta. They are some of the most abundant and commonly observed lizards in the deserts of western North America, known for cycling between three colorized breeding patterns and is best described in the common side-blotched lizard. They commonly grow to 6 inches including the tail, with the males normally being the larger sex. Males often have bright throat colors.
The common side-blotched lizard is a species of side-blotched lizard in the family Phrynosomatidae. The species is native to dry regions of the western United States and northern Mexico. It is notable for having a unique form of polymorphism wherein each of the three different male morphs utilizes a different strategy in acquiring mates. The three morphs compete against each other following a pattern of rock paper scissors, where one morph has advantages over another but is outcompeted by the third.
Sceloporus magister, also known as the desert spiny lizard, is a lizard species of the family Phrynosomatidae, native to the Chihuahuan Desert and Sonoran Desert of North America.
The eastern fence lizard is a medium-sized species of lizard in the family Phrynosomatidae. The species is found along forest edges, rock piles, and rotting logs or stumps in the eastern United States. It is sometimes referred to as the prairie lizard, fence swift, gray lizard, gravid lizard, northern fence lizard or pine lizard. It is also referred to colloquially as the horn-billed lizard. One of its most notable behaviors is that of its escape behavior when encountering fire ants, which have been known to invade and negatively affect many of their populations.
The sagebrush lizard or sagebrush swift is a common species of phrynosomatid lizard found at mid to high altitudes in the western United States. It belongs to the genus Sceloporus in the Phrynosomatidae family of reptiles. Named after the sagebrush plants near which it is commonly found, the sagebrush lizard has keeled and spiny scales running along its dorsal surface.
The Texas spiny lizard is a species of phrynosomatid lizard native to the south central United States, in the states of Texas, Arizona and Oklahoma, and northeastern Mexico in the states of Coahuila, Nuevo León, Tamaulipas, and San Luis Potosí. They are quite common throughout their range, where they can be found in trees or on fences.
Sceloporus malachiticus, the emerald swift or green spiny lizard, is a species of small lizard in the Phrynosomatidae family, native to Central America.
Sceloporus variabilis, commonly known as the rose-bellied lizard, is a species of lizard which is found from Central America to southern Texas
The Mojave fringe-toed lizard is a species of medium-sized, white or grayish, black-spotted diurnal lizard in the family Phrynosomatidae. It is adapted to arid climates and is most commonly found in sand dunes within the Mojave Desert. Fringe-toed lizards are characterized by their fringed scales on their hind toes which make locomotion in loose sand possible.
Sceloporus occidentalis bocourtii, commonly known as the Coast Range fence lizard, is a subspecies of Sceloporus occidentalis, the Western fence lizard.
Sceloporus uniformis, also known as the yellow-backed spiny lizard, is a reptile of the family Phrynosomatidae. It is native to the Mojave and Great Basin deserts. Until recently, it was considered to be a subspecies of Sceloporus magister.
Sceloporus jarrovii, also known commonly as Yarrow's spiny lizard, is a species of lizard in the family Phrynosomatidae. The species is native to the southwestern United States and northern Mexico. There are two recognized subspecies.
The plateau fence lizard is a species of spiny lizard in the family Phrynosomatidae.
Sceloporus dugesii, also known commonly as Dugès' spiny lizard and la lagartija espinosa de Dugès del este in Mexican Spanish, is a species of lizard in the family Phrynosomatidae. The species is endemic to Mexico.
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