Western Fence Lizard
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The western fence lizard (''Sceloporus occidentalis'') is a common
lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
of
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
,
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...
,
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
,
Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...
,
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
,
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
,
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
,
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
, Northern
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
, and the surrounding area. As the ventral abdomen of an adult is characteristically blue, it is also known as the blue-belly.


Taxonomy

Taxonomy for the western fence lizard has been under much debate. ''S. occidentalis'' belongs in the order
Squamata Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, ...
(snakes and lizards) and the suborder
Iguania Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons, agamids, and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed t ...
. The family in which it belongs is still under scrutiny. The family
Phrynosomatidae The Phrynosomatidae are a diverse family of lizards, sometimes classified as a subfamily (Phrynosomatinae), found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny ...
, along with seven other families, used to be included in the single family
Iguanidae The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana. Taxonomy Iguanidae is thought to be the sister group to the collared lizards (family Crotaph ...
, until Frost and Etheridge's (1989) analysis of iguanian systematics suggested the family be divided. Most literature, however, still place the phrynosomatids in Iguanidae. Five subspecies are recognized, as follows: *San Joaquin fence lizard, ''
Sceloporus occidentalis biseriatus ''Sceloporus occidentalis biseriatus'' is a subspecies of the western fence lizard. The common name of ''S.o. biseriatus'' is the San Joaquin fence lizard. There are several subspecies of the western fence lizard, all of which are found in the f ...
'' *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 ''Sceloporus occidentalis taylori'' is a subspecies of the western fence lizard, commonly called the Sierra fence lizard. Several subspecies of the western fence lizard, a species of phrynosomatid lizard, are found in the far western part of Nor ...
'' Some authors have raised the
island fence lizard An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island i ...
to
specific Specific may refer to: * Specificity (disambiguation) * Specific, a cure or therapy for a specific illness Law * Specific deterrence, focussed on an individual * Specific finding, intermediate verdict used by a jury in determining the fina ...
rank, ''
Sceloporus becki ''Sceloporus becki'', also known as the island fence lizard, is a species of lizard endemic to the Channel Islands of California. Taxonomy It was once considered a subspecies of the western fence lizard (''Sceloporus occidentalis''), but is now ...
''. However, recent work in
molecular systematics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
has suggested there are four
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
s and 11 genetically separable populations, and the
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
will probably have to be redefined.


Identification

Western fence lizards measure 5.7–8.9 cm (snout-vent length)Stebbins, Robert C. "A Field Guide to Western Reptiles and Amphibians." 3rd ed. Peterson Field Guides, 2003 and a total length of about 21 cm.Sceloporus occidentalis
from Idaho Museum of Natural History
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.
from San Diego Natural History Museum
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 Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
. 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 The eastern fence lizard (''Sceloporus undulatus'') is a medium-sized species of lizard in the Family (biology), family Phrynosomatidae. The species is found along forest edges, rock piles, and rotting logs or stumps in the eastern United States. I ...
, ''S. undulatus'', instead of having one large patch on its throat, has two small patches. The
sagebrush lizard The sagebrush lizard or sagebrush swift (''Sceloporus graciosus'') is a common species of phrynosomatid lizard found at mid to high altitudes in the western United States of America. It belongs to the genus ''Sceloporus'' (spiny lizards) in ...
, ''S. graciosus'', lacks yellow limbs and has smaller dorsal scales. ''S. occidentalis'' also resembles the
side-blotched lizard 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 patternsSinervo, B.; C.M. Live ...
, ''Uta stansburiana''. However, the axilla of ''U. stansburiana'' usually has a black spot behind it and it has a complete
gular fold A gular fold is a feature of the body of lizards and many other reptiles. It is a granular fold found on the ventral throat, located immediately in front of the forelegs. See also * Gular (disambiguation) Gular is of or pertaining to the throat, ...
.


Distribution and habitat

Although California is the heart of the range of this lizard, it is also found in eastern and southwestern
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
(some populations are found even north of
Seattle, Washington Seattle ( ) is a port, seaport city on the West Coast of the United States. It is the county seat, seat of King County, Washington, King County, Washington (state), Washington. With a 2020 population of 737,015, it is the largest city in bo ...
), as well as in the
Columbia River Gorge The Columbia River Gorge is a canyon of the Columbia River in the Pacific Northwest of the United States. Up to deep, the canyon stretches for over as the river winds westward through the Cascade Range, forming the boundary between the sta ...
, southwestern
Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...
,
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
, western
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
, northwestern
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
, 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 The Tualatin Valley is a farming and suburban region southwest of Portland, Oregon in the United States. The valley is formed by the meandering Tualatin River, a tributary of the Willamette River at the northwest corner of the Willamette Valley, ...
, around Henry Hagg Lake. The western fence lizard occupies a variety of habitats. It is found in grassland, broken
chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...
, sagebrush, woodland, coniferous forest, and farmland, and occupies elevations from sea level to 10,800 ft. 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.


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 and such developed shorter limbs and toes. The habitat loss also causes a decrease in the number of scales. This is because of a UHI effect of urban areas, increasing the temperature year round. 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.


Behavior

These lizards are diurnal, and are commonly seen basking on paths, rocks, and fence posts, and other suitable sunny locations. They can change color from light grey or tan to nearly jet black for the purpose of
thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
while basking. ''S. occidentalis'' goes through a period of
brumation Dormancy is a period in an organism's life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be clos ...
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. The western fence lizard primarily eats small invertebrates, but may consume any appropriately sized prey item.


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.


Lyme disease

Studies have shown
Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia'' bacterium, which is spread by ticks in the genus ''Ixodes''. The most common sign of infection is an expanding red rash, known as erythema migran ...
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 the lizard's blood kills the
bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
in the tick that causes Lyme disease. The infection inside the ticks' gut is therefore cleared and the tick no longer carries Lyme disease.


References

{{Authority control Sceloporus
Western fence lizard The western fence lizard (''Sceloporus occidentalis'') is a common lizard of Arizona, New Mexico, California, Idaho, Nevada, Oregon, Utah, Washington (state), Washington, Northern Mexico, and the surrounding area. As the ventral abdomen of an ad ...
Reptiles of the United States Reptiles of Mexico Fauna of the Western United States Fauna of the Sierra Nevada (United States) Fauna of the California chaparral and woodlands Fauna of the San Francisco Bay Area
Western fence lizard The western fence lizard (''Sceloporus occidentalis'') is a common lizard of Arizona, New Mexico, California, Idaho, Nevada, Oregon, Utah, Washington (state), Washington, Northern Mexico, and the surrounding area. As the ventral abdomen of an ad ...
Western fence lizard The western fence lizard (''Sceloporus occidentalis'') is a common lizard of Arizona, New Mexico, California, Idaho, Nevada, Oregon, Utah, Washington (state), Washington, Northern Mexico, and the surrounding area. As the ventral abdomen of an ad ...