Range in California: Green
Red: San Clemente Night Lizard
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We have no images of this subspecies or its habitat. If you have any pictures we can use, please send them to us!
You can get pictures and information about San Nicolas Island here and here,
and view a picture of a Night Lizard from San Nicolas Island here.
You can also refer to the other subspecies Xantusia riversiana reticulata, which is very similar, shown below.
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Adult X. r. reticulata, Santa Barbara Island
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Adult X. r. reticulata, striped form, San Clemente Island © Bob Haase |
| 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 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. On San Nicolas Island, a reddish brown color is most common and some lizards are uniformly colored above. (Striped lizards of a different subspecies occur on other islands, and might occur on San Nicolas Island, also.) The underside is slate bluish, cream or pale yellow. The undersides of the feet are sometimes yellowish. |
| Behavior and Natural History |
| 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. Active throughout the year. Grows and matures slowly, living to at least 12 years old |
| Diet |
| Eats small invertebrates including insects, spiders, scorpions, and marine isopods along with plant material (which can make up to one-third of its diet.) |
| Reproduction |
| Breeds in March and April. Viviporous, bearing 2-9 live young mostly in September.
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. |
| Range |
| Endemic to California. Found only on San Nicolas Island off the southern California coast. |
| 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. |
| Taxonomic Notes |
| Two subspecies of X. riversiana are still recognized by on the official lists of the SSAR and the CNAH, X. r. reticulata , and X. r. riversiana. These names are hardly used by anyone else, and I have found very little information regarding differences between these subspecies. |
| Conservation Issues (Conservation Status) |
Protected since 1967. Introduced game and livestock and introduced predators such as feral cats and rats have endangered night lizards on the Channel Islands. San Nicolas Island has no more introduced game or livestock, but past overgrazing and its accompanying erosion have removed much of the topsoil.
The U.S. Navy administers San Nicolas Island, and has petitioned to have lizards from the island removed from the Endangered Species List. Reportedly a large number of lizards thrives on the island. |
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Taxonomy |
| Family |
Xantusiidae |
Night Lizards |
| Genus |
Xantusia |
Night Lizards |
| Species |
riversiana |
Island Night Lizard |
Subspecies
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riversiana |
San Nicolas Night Lizard |
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Original Description |
Xantusia riversiana - Cope, 1883 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 35, p. 29
from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
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Meaning of the Scientific Name |
Xantusia - honors Xantus, John
riversiana - honors Rivers, James, J.
from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
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Alternate Names |
Xantusia riversiana - Island Night Lizard (with no subspecies recognized)
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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. reticulata - San Clemente Night Lizard
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More Information and References |
Natureserve Explorer
California Dept. of Fish and Game
US Fish & Wildlife Service
IUCN Red List
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., & F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
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.
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.
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The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game.
Listing is by species, not just this subspecies.
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Organization
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Status Listing
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| U.S. Endangered Species Act (ESA) |
FT |
Threatened |
| California Endangered Species Act (CESA) |
None |
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| California Department of Fish and Game |
None |
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| Bureau of Land Management |
None |
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| USDA Forest Service |
None |
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| Natureserve Global Conservation Status Ranks |
G1 S1 |
Critically Imperiled |
World Conservation Union - IUCN Red List
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IUCN:LC |
Least Concern |
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