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A Guide to the Amphibians
and Reptiles of California


San Clemente Night Lizard - Xantusia riversiana reticulata

Smith, 1946
Click on a picture for a larger view



Island Night Lizards Range Map
Range in California: Red

Bright Green: San Nicolas Night Lizard



observation link





San Clemente Night Lizard San Clemente Night Lizard San Clemente Night Lizard
Adult, Santa Barbara Island Adult, Santa Barbara Island
San Clemente Night Lizard San Clemente Night Lizard San Clemente Night Lizard
Adult, Santa Barbara Island Adult, Santa Barbara Island
San Clemente Night Lizard San Clemente Night Lizard San Clemente Night Lizard
Adult, Santa Barbara Island Adult, Santa Barbara Island Adult, Santa Barbara Island
San Clemente Night Lizard San Clemente Night Lizard San Clemente Night Lizard
Adult, striped form, San Clemente Island
© Bob Haase
Adult, San Clemente Island
© Bob Haase
Adult, San Clemente Island
© Bob Haase
  Night lizard scales  
  Island Night Lizards have small granular scales on soft skin.  
     
Habitat
San Clemente Night Lizard Habitat San Clemente Night Lizard Habitat San Clemente Night Lizard Habitat
Santa Barbara Island Santa Barbara Island Santa Barbara Island and Sutil Islet,
early Summer 
San Clemente Night Lizard Habitat San Clemente Night Lizard Habitat San Clemente Night Lizard Habitat
Santa Barbara Island, early Summer  Rocky cliff-edge and Sutil Islet, early Summer, Santa Barbara Island
Small canyon in Spring, with blooming Giant CoreopsisSanta Barbara Island.
© Tim Burkhardt
San Clemente Night Lizard Habitat San Clemente Night Lizard Habitat San Clemente Night Lizard Habitat
Grassy plateau, top of
Santa Barbara Island
View looking down at Elephant Seal Beach, Santa Barbara Island Dormant Giant Coreopsis, Santa Barbara Island, early summer
   
Description
 
Size
2.5 - 4.2 inches long from snout to vent (6.3 - 10.6 cm). (Stebbins 2003)
The largest of the Xantusiids, growing from about 5 - 8 inches long including the tail.

Appearance
A medium-sized lizard with granular scales, soft skin that appears loose around the neck and shoulders, large plates on the head, lidless eyes with vertical pupils, a gular fold, and a fold of skin low on each side of the body.
Two rows of supraoculars and 16 lengthwise rows of squarish scales at the midbelly.
Color and Pattern
Color and pattern are variable - Brown, olive-brown, grayish, rusty, or yellowish-brown with dark brown or black spots or blotches, sometimes with full or broken light stripes edged with black along the sides of the back.
Striped lizards occur on San Clemente Island, but rarely on Santa Barbara Island.
The underside is slate bluish, cream or pale yellow.
The undersides of the feet are sometimes yellowish.

Life History and Behavior

Activity
Once considered nocturnal, but apparently diurnal but sedentary, secretive, and rarely seen.
Spends most of its time under cover, but occasionally seen exposed on the surface in daylight.
The mild climate of the islands this lizard inhabits allows it to remain active throughout the year.
Grows and matures slowly, living to at least 12 years old
Diet and Feeding
Eats small invertebrates including insects, spiders, scorpions, and marine isopods along with plant material (which can make up to one-third of its diet.)
Breeding
Reproductive potential is low.
Adults do not reach sexual maturity until their 3rd or 4th year and only about half of all females reproduce each year.
Breeds in March and April.
Viviporous, bearing 2-9 live young mostly in September.

Habitat
Found in almost any island habitat that provides it protection and shade - maritime desert scrub, grassland, chaparral, oak savanna, cactus, dry streambeds, cliffs, rocky beaches, sparsely-vegetated areas. Takes shelter in cracks in rocks or in the ground, and under surface objects such as rocks, fallen vegetation and beach driftwood.

Santa Barbara Island is a flat tree-less plateau with grasses, small shrubs, introduced ice plant, prickly-pear cactus and Giant Coreopsis. There are a few small rocky canyons along the edge with dense vegetation.

Geographical Range
Endemic to California.
Found only on islands off the southern California coast - Santa Barbara Island, Sutil Islet, and San Clemente Island.

Notes on Taxonomy
Two subspecies of X. riversiana are still recognized by on the official lists of the SSAR and the CNAH:
X. r. reticulata

X. r. riversiana

These names are hardly used by anyone else, and I have found very little information regarding differences between these subspecies.


Alternate and Previous Names (Synonyms)

Xantusia riversiana - Island Night Lizard (Stebbins 1985, 2003)
Klauberina riversiana - Island NIght Lizard (Stebbins 1966)
Xantusia riversiana - Island Night Lizard (Smith 1946, Stebbins 1954)

Conservation Issues  (Conservation Status)
Protected since 1967. This lizard's restricted habitat has been threatened by the grazing of introduced livestock and game, (most of which have now been removed) and by introduced predators such as feral cats and possibly rats. It is also preyed upon heavily by native birds and mammals. In 1990 the USFWS categorized the status of lizards on San Clemente Island as stable. A 1991 study by Fellers and Drost determined that the population on Santa Barbara Island is not threatened.
The U.S. Navy administers San Clemente and San Nicolas Islands, and has petitioned to have lizards from those islands removed from the Endangered Species List. Santa Barbara Island and Sutil Islet are protected as National Park property.

On 4/1/14 the U.S. Fish and Wildlife Service removed Xantusia riversiana, the island night lizard, from the Federal List of Endangered and Threatened Wildlife. More Information
Taxonomy
Family Xantusiidae Night Lizards Baird, 1858
Genus Xantusia Night Lizards Baird, 1859 “1858”
Species riversiana Island Night Lizard Cope, 1883
Subspecies

reticulata San Clemente Night Lizard Smith, 1946
Original Description
Xantusia riversiana - Cope, 1883 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 35, p. 29
Xantusia riversiana reticulata - Smith, 1946 - Journ. Washington Acad. Sci., Vol. 36, p. 392

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

Meaning of the Scientific Name
Xantusia - honors Xantus, John
riversiana
- honors Rivers, James, J.
reticulata - Latin - net-like - probably refers to the pattern.

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

Related or Similar California Lizards
X. henshawi - Granite Night Lizard
X. gracilis - Sandstone Night Lizard
X. vigilis - Yucca Night Lizard
X. sierrae - Sierra Night Lizard
X. r. riversiana - San Nicolas Night Lizard

More Information and References
California Department of Fish and Wildlife

US Fish & Wildlife Service

IUCN Red List

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.

Thelander, C. G., ed. Life on the Edge: A Guide to California's Endangered Natural Resources Volume I: Wildlife.
Biosystems Books, Santa Cruz, California. 1994.

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

Fellers, G.M. and Drost, C.A. 1991. Xantusia riversiana. Catalogue of American Amphibians and Reptiles 516: 1-4.

U.S. Fish and Wildlife Service (USFWS). 1990. Endangered and threatened species recovery program: report to Congress.

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.

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.


The Special Animals List listing is by species, not just this subspecies.


Organization
Status Listing
NatureServe Global Ranking G3 Vulnerable—At moderate risk of extinction due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors.
NatureServe State Ranking S3 Vulnerable in the state due to a restricted range, relatively few populations (often 80 or fewer), recent and widespread declines, or other factors making it vulnerable to extirpation from the state.
U.S. Endangered Species Act (ESA) Removed from list 4/1/14
FT - 8/11/77 - Threatened
FPD - 2/4/13 Federally Proposed (Delisting)
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None
IUCN LC Least Concern


 

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