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A Guide to the Amphibians
and Reptiles of California


Island Fence Lizard - Sceloporus occidentalis becki

Van Denburgh, 1905
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Western Fence Lizards California Range MapRange in California: Bright Green

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Island Fence Lizard Island Fence Lizard Island Fence Lizard
Adult male, Santa Cruz Island,  Santa Barbara County
Island Fence Lizard Island Fence Lizard Island Fence Lizard
Adult male, Santa Cruz Island,
Santa Barbara County
Adult male, Santa Cruz Island,
Santa Barbara County
Adult male, Santa Cruz Island,
Santa Barbara County
Island Fence Lizard Island Fence Lizard Island Fence Lizard
Adult male, Santa Cruz Island Juvenile, Santa Cruz Island Adult male, Santa Cruz Island
Island Fence Lizard fence lizard with ticks lizard skin
Adult, Santa Cruz Island © Steve Bird Adult male Western Fence Lizard with ticks on the side of his head.

In California, western black-legged ticks (deer ticks) are the primary carriers of Lyme disease. Very tiny nymphal deer ticks are more likely to carry the disease than adults. A protein in the blood of Western Fence Lizards kills the bacterium in these nymphal ticks when they attach themselves to a lizard and ingest the lizard's blood. This could explain why Lyme disease is less common in California than it is in some areas such as the Northeastern states, where it is epidemic.

More Information
Western Fence Lizards have overlapping keeled scales with spines on them over much of their body.
     
Habitat
Island Fence Lizard Habitat Island Fence Lizard Habitat Island Fence Lizard Habitat
Habitat, Santa Cruz Island
Habitat, beach driftwood on
Santa Cruz Island
Habitat, Santa Cruz Island
santa cruz island Island Fence Lizard Habitat Island Fence Lizard Habitat
Habitat, Santa Cruz Island
Habitat, Santa Cruz Island
Habitat, Santa Cruz Island
     
Short Videos of Other Subspecies of Western Fence Lizard
A male Northwestern Fence Lizard defecates off the side of a Butte County fence, wipes himself off, then does a territorial push-up display. I'm not going out of my way trying to film this behavior - I can only take what I get - so here we see another Northwestern Fence Lizard doing his business for the camera. It's like they're trying to tell me something. A male Northwestern Fence Lizard fights with a female in Placer County © Rod
Coast Range Fence Lizard Coast Range Fence Lizard Coast Range Fence Lizard
A few fence lizards in Contra Costa County. A male fence lizard on a tree in Alameda County. Several juvenile fence lizards come out to bask in the sun on a cool and windy morning in early March.
Great Basin Fence Lizard Great Basin Fence Lizard Great Basin Fence Lizard
A female fence lizard runs across a wall in Riverside County and encounters a male who pursues her. She rejects him and he runs to an open spot on top of the wall and does a push-up display. A male fence lizard in Inyo County defensively showing his throat color and doing push-ups. Large, dark phase Great Basin Fence Lizards bask and eat ants off rocks in Inyo County.
Sierra Fence Lizard Sierra Fence Lizard Coast Range Fence Lizards
Sierra Fence lizards run around a rocky area in the woods 8,000 ft. high in the Sierra Nevada mountains. A Sierra Fence Lizard, or intergrade, runs around rocks in the forest up at 5,600 ft. in Tuolumne County. Two Coast Range Fence Lizards observed during the breeding season in early May in San Benito County. The first lizard, a female, has moved from her perch on a rock to a nearby rock in order to get away from the photographer. She begins a territorial push-up display when a male comes up the side of the rock and begins to pursue her. She arches her back and hops away in order to reject him. She may have already mated and is bearing eggs, or maybe he is not her type. He finally stops and does a push-up display, possibly to continue trying to entice her, or possibly to warn the photographer that this is his territory.
San Joaquin Fence Lizard
These two videos show a Placer County Northwestern Fence Lizard appearing to taunt a garter snake (a Mountain Gartersnake is my guess, because it lacks red.) The lizard keeps moving down towards the snake but when the snake moves towards the lizard, apparently trying to catch it for dinner, the lizard runs up the wall away from the snake. © Rod

San Joaquin Fence Lizards on trees along a river in early spring.

   
Description
 
Size
2.25 - 3.5 inches long from snout to vent (5.7 - 8.9 cm). (Stebbins 2003)

Appearance
A fairly small lizard with keeled and pointed dorsal scales of equal size on the back, sides, and belly.
Scales on the backs of the thighs are mostly keeled, and abruptly smaller.
Color and Pattern
Color is brown, gray, or black with blotches.
Sometimes light markings on the sides of the backs form stripes or irregular lines, and sometimes dark blotching may form irregular bands.
The belly is light in color.
The rear of the limbs is yellow or orange.
The sides of the belly are blue.
Male / Female Differences
Males have blue markings on the sides of the belly edged in black, a black patch on the throat, enlarged postanals, enlarged femoral pores, and a swollen tail base.
Some scales on a male's back become blue or greenish when he is in the light phase.

Females have faint or absent blue markings on the belly, no blue or green color on the upper surfaces, and dark bars or crescents on the back.
Young
Juveniles have little or no blue on the throat and faint blue belly markings or none at all.

Life History and Behavior

Activity
Diurnal.
Often seen basking in the sun on rocks, downed logs, trees, fences, and walls.
Prefers open sunny areas.
Active when temperatures are warm, becomes inactive during periods of extreme heat or cold, when they shelter in crevices and burrows, or under rocks, boards, tree bark, etc.
The mild climate of the islands this lizard inhabits probably allow activity all year.

Common and easily encountered in the right habitat.
This is probably the species of lizard most often seen in the state due to its abundance in and near populated areas and its conspicuous behavior.
Territoriality
Males establish and defend a territory containing elevated perches where they can observe mates and potential rival males.
Males defend their territory and try to attract females with head-bobbing and a push-up display that exposes the blue throat and ventral colors. Territories are ultimately defended by physical combat with other males.
Defense
The tail detaches easily to distract a potential predator allowing the lizard to escape.
Diet and Feeding
Eats small, mostly terrestrial, invertebrates such as crickets, spiders, ticks, and scorpions, and occasionally eats small lizards including its own species.
Breeding
Mates in early to late spring, depending on the elevation of the location.
Courtship and copulation typically occurs from March to June.
Egg laying occurs 2 - 4 weeks after copulation.
Females dig small pits in loose damp soil where they lay 1 - 3 clutches of 3 - 17 eggs usually from May to July.
Eggs hatch in about 60 days, usually from July to September.

Western Fence Lizards and Lyme Disease
In California, western black-legged ticks (deer ticks) are the primary carriers of Lyme disease. Very tiny nymphal deer ticks are more likely to carry the disease than adults. A protein in the blood of Western Fence Lizards kills the bacterium in these nymphal ticks when they attach themselves to a lizard and ingest the lizard's blood. This could explain why Lyme disease is less common in California than it is in some areas such as the Northeastern states, where it is epidemic.

More Information: (Berkeleyan April 1998)


In an interesting twist, UC Berkeley researchers have found that when fence lizards are removed from an area, the population of Lyme disease-carrying ticks plummets. Up to 90 percent of juvenile Western black-legged ticks, the species that carries the Lyme disease bacteria, feed on Western Fence Lizards. When lizards are no longer available, 95 percent of the ticks fail to find another host to feed on.

More Information: (Berkeley News February 2011)

Habitat
Prefers open sunny areas with elevated perching spots, including stream banks, beach driftwood, grassy hillsides, fences, and walls of human settlements.

Geographical Range
This subspecies is endemic to California. Found only in the Channel Islands off the southern California coast on Santa Cruz, Santa Rosa, and San Miguel Islands.

The species Sceloporus occidentalis ranges from northern Baja California north to Washington and east to Idaho, Nevada and Utah.

The ranges of subspecies shown on the range map above are based mostly on Ryan Calsbeek's distribution map.

Full Species Range Map
An alternate interpretation of the ranges of S. o. longipes and S. o. occidentalis showing S. o. occidentalis present in northeastern California and central Oregon instead of S. o. longipes can be seen here.

Elevational Range
The species Sceloporus occidentalis - Western Fence Lizard, is found at elevations from sea level to around 10,800 ft.
(3,300 m.) (Stebbins, 2003) This subspecies will not be found at such a high elevation.

Notes on Taxonomy
The taxonomy of Sceloporus occidentalis needs to be studied further. For years six subspecies have been recognized based on geographic variation in morphology, but molecular studies have identified 4 major clades and 11 different genetic groups in California (James Archie, Cal State University Long Beach).

Many authorities have already accepted research that concludes that S. o. becki, the Island Fence Lizard, is a unique species - Sceloporus becki. (Wiens & Reeder, 1997) (Bell, 2001) Others have shown that S. o. taylori should not be classified as a distinct subspecies.

The current taxonomy does not correspond with the ongoing research, so it is certain that in the future the current subspecies and their ranges will be completely revised, probably with several new species described. For this reason some experts no longer recognize any subspecies of S. occidentalis pending further studies. This site follows the SSAR list of 2008 and continues to recognize 6 subspecies.


Alternate and Previous Names (Synonyms)

Commonly called: Bluebelly, Blue-bellied Lizard, Fence Lizard, Swift, Fence Swift

Sceloporus occidentalis - Western Fence Lizard (no subspecies recognized) (Stebbins 2003)
Sceloporus occidentalis becki - Island Fence Lizard (Stebbins 1966, 1985)
Sceloporus occidentalis becki - Channel Island Fence Lizard (Smith 1946)

Conservation Issues  (Conservation Status)
None
Taxonomy
Family Phrynosomatidae Zebra-tailed, Earless, Fringe-toed, Spiny, Tree, Side-blotched, and Horned Lizards Fitzinger, 1843
Genus Sceloporus Spiny Lizards Wiegmann, 1828
Species occidentalis Western Fence Lizard Baird and Girard, 1852
Subspecies

becki Island Fence Lizard Van Denburgh, 1905
Original Description
Sceloporus occidentalis - Baird and Girard, 1852 - Prox. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 175
Sceloporus occidentalis becki - Van Denburgh, 1905 - Proc. California Acad. Sci., Ser. 3, Zool. Vol. 4, No. 1, p. 9, pl. 4

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
Sceloporus - Greek -skelos leg and porus - pore or opening - refers to the femoral pores on hind legs
occidentalis
- Latin - western - refers to its western distribution
becki - honors Beck, Rollo Howard

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Related or Similar California Lizards
Western Fence Lizards:
Sceloporus occidentalis biseriatus - San Joaquin Fence Lizard
Sceloporus occidentalis bocourtii - Coast Range Fence Lizard
Sceloporus occidentalis longipes - Great Basin Fence Lizard
Sceloporus occidentalis occidentalis - Northwestern Fence Lizard
Sceloporus occidentalis taylori - Sierra Fence Lizard

Sagegrush Lizards:
S. graciosus graciosus - Northern Sagebrush Lizard
S. graciosus gracilis - Western Sagebrush Lizard
S. graciosus vandenburgianus - Southern Sagebrush Lizard

More Information and References
California Department of Fish and Wildlife

Stebbins, Robert C., and McGinnis, Samuel M.  Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.

Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.

Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.

Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.

Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.

Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Turtles and Lizards of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.

Jones, Lawrence, Rob Lovich, editors. Lizards of the American Southwest: A Photographic Field Guide. Rio Nuevo Publishers, 2009.

Smith, Hobart M. Handbook of Lizards, Lizards of the United States and of Canada. Cornell University Press, 1946.

Schoenherr, Allan A. Natural History of the Islands of California. The University of California Press. 2003.

Wiens & Reeder (1997 Herpetological Monographs 11: 1-101)

Bell (2001 Bulletin of the Maryland Herpetological Society 37(4): 137-142)

S. Morey. Western Fence Lizard Family: Phrynosomatidae R022. California Wildlife Habitat Relationships System California Department of Fish and Game. Originally published in Zeiner, D.C., W.F.Laudenslayer, Jr., K.E. Mayer, and M. White, eds. 1988-1990.

Conservation Status

The following status listings come from the Special Animals List and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.


This animal is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.


Organization
Status Listing
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None
IUCN


 

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