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Desert Night Lizard - Xantusia vigilis

Baird, 1859 “1858”

(Xanatusia vigilis vigilis - Yucca Night Lizard)
Click on a picture for a larger view



Night Lizards Range MapRange in California: Red

Green: Sierra Night Lizard

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Desert Night Lizard Desert Night Lizard Desert Night Lizard
  Adult, Kern County  
Desert Night Lizard Desert Night Lizard Desert Night Lizard
Adult, Riverside County Adult, Kern County
Desert Night Lizard Desert Night Lizard Desert Night Lizard
Adult, Kern County Adult, Kern County
Desert Night Lizard Desert Night Lizard Desert Night Lizard
Adult, San Bernardino County Adult, Kern County Juvenile, Inyo County
Desert Night Lizards Great Basin Collared Lizard  
Adult and sub-adult, San Diego County
© Bruce Edley
The Night Lizards, genus Xantusia, have small granular scales on soft skin.
X. henshawi is seen here.

 
Tail Loss Defense
Desert Night Lizard Desert Night Lizard tail  
This adult lizard dropped its tail as a defesive measure. (You can see the tail wriggling after it was dropped off in the video below.)

 
Habitat
Desert Night Lizard Habitat Desert Night Lizard Habitat Desert Night Lizard Habitat
Habitat, San Bernardino County Habitat, Kern County Rocky habitat, Kern County
Desert Night Lizard Habitat Desert Night Lizard Habitat  
Habitat, Kern County

Habitat, Inyo County  
Short Videos
Desert Night Lizard Desert Night Lizard tail  
A view of some Desert Night Lizards, discovered underneath dead Joshua Tree branches in the desert, close up and in motion. The detached tail of a Desert Night Lizard wriggles on the ground. (It kept wriggling for almost 4 minutes.)

Many species of lizards release their tail when they want to escape from a potential predator. The tail then continues to wriggle like a living creature. The aim is to momentarily distract the predator away from the lizard's vulnerable body, allowing it to escape, while the predator is left holding or trying to catch the expendable tail. This tail dropping is called "Autotomy." Losing the tail does not seriously harm the lizard, and may save its life, but the loss of a tail might have a negative effect on the lizard's social standing. Dropped tails do grow back, but these regenerated tails are often not as long or as perfect as the original.
 
Description

Size
1.5 - 2.75 inches long from snout to vent (3.8 - 7 cm). (Stebbins 2003)
Appearance
A small thin lizard with soft skin with fine granular scales on most of the body, a head covered with large plates, lidless eyes with vertical pupils, a gular fold, and a detachable tail. Males have enlarged femoral pores. Dorsal scales in 30 - 50 lengthwise rows at mid-body.

Color is olive, grayish, or brown with light brown or black spots, sometimes forming narrow stripes. A narrow beige stripe, edged in black, extends from the eye to the shoulder. The underside is whitish and made up of large square scales, usually in 12 rows.
Behavior and Natural History
Diurnal (contrary to the common name) and crepuscular. May be nocturnal during the heat of the summer. Abundant, but secretive - spending most of its life undercover in and underneath fallen vegetation and debris, such as Joshua tree branches, dead yucca clumps, logs, pine bark, and also under rocks and in rock crevices. Not typically active on the surface away from cover. Sedentary, spending most of its life in a small area.

When frightened, runs away quickly and dashes under cover. The tail breaks off easily and continues wriggling to distract would-be predators as the lizard runs away as you can see in this video. This does not hurt the lizard, although it might suffer from the stress of attempted predation, the loss of fatty energy that is stored in the tail, and have difficulties finding a mate during breeding season due to a less healthy appearance.

In 2010, researchers at UC Santa Cruz discovered that Xantusia vigilis live in family groups, showing social behavior more typical of mammals and birds such as primates, ground squirrels, and woodpeckers. (A few other lizard species have also evolved a social system around a nuclear family.) The young night lizards remain with the father, mother, and siblings for several years, all living under the same plant debris.The young feed themselves and do not receive any direct care from the parents. It is not yet known what survival advantages the group living arrangement provides.
(Davis, et. al. Reported in ScienceDaily 10/8/2010.)
Diet
Eats small invertebrates inhabiting the decaying vegetation in which it lives including ants, termites, beetles, caterpillars, crickets, and spiders.
Reproduction
Breeds in late spring. Viviparous: young are born live, 1-3 per brood, from August to October.
Range
Found on the desert slopes of the Peninsular ranges, throughout the Mojave Desert, along the east slopes of the Sierra Nevada Mountains north to west of Bishop, the Inyo and Panamint mountains, the Greenhorn and Piute Mountains and upper Kern River Canyon in the southern Sierra Nevada Mountains, the coastal side of the mountains in upper Santa Clara River drainage, the headwaters of Big Tujunga and the upper San Gabriel River drainage, and the inner coast ranges at the Panoche Hills and Pinnacles National Monument. Also found on Santa Catalina Island, but these may have been introduced. From sea level to 9,300 ft. (2,830 m). (Stebbins 2003)
Ranges out of California east into Nevada, Arizona, and extreme southwest Utah.
Habitat
Utilizes a variety of habitats in arid and semi-arid areas, including those grown with Joshua tree, desert scrub, pinon-juniper, basin sagebrush, chaparral, pine-oak woodland, and yucca.
Taxonomic Notes
Several subspecies of Xantusia vigilis are traditionally recognized, including two in California - X. v. vigilis, and X. v. sierrae.

Using nuclear DNA studies, Leavitt et al, 2007, provide support for the recognition of new species within the X. vigilis complex, including X. wigginsi in California, but they continue to recognize the subspecies X. v. vigilis and X. v.sierrae. In addition, they identify several major clades, four of which occur in California - X. vigilis, X. wigginsi (now a full species), a Yucca Valley clade, and a San Jacinto clade.

The 2008 Society for the Study of Amphibians and Reptiles Standard Names List uses X. vigilis based on Sinclair et. al (2004, Am. Nat. 164:396-141).
Conservation Issues  (Conservation Status)
None

Taxonomy
Family Xantusiidae Night Lizards Baird, 1858
Genus Xantusia Night Lizards Baird, 1859 “1858”
Subspecies

vigilis Desert Night Lizard Baird, 1859 “1858”
Original Description
Xantusia vigilis - Baird, 1858 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 10, p. 255

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

Meaning of the Scientific Name
Xantusia - honors Xantus, John
vigilis
- Latin - alert or watchful - possibly refers to the lack of eyelids

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

Alternate Names
Xantusia vigilis vigilis - Yucca Night Lizard

Related or Similar California Lizards
X. henshawi - Granite Night Lizard
X. gracilis - Sandstone Night Lizard
X. sierrae - Sierra Night Lizard
X. r. reticulata - San Clemente Night Lizard
X. wigginsi - Baja California Night Lizard

More Information and References
Natureserve Explorer

California Dept. of Fish and Game

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.

Lemm, Jeffrey. Field Guide to Amphibians and Reptiles of the San Diego Region (California Natural History Guides). University of California Press, 2006.

DEAN H. LEAVITT, ROBERT L. BEZY, KEITH A. CRANDALL, JACK W. SITES JR (2007)
Multi-locus DNA sequence data reveal a history of deep cryptic vicariance and habitat-driven convergence in the desert night lizard Xantusia vigilis species complex (Squamata: Xantusiidae)
Molecular Ecology 16 (21), 4455–4481.

(Alison R. Davis, Ammon Corl, Yann Surget-Groba, Barry Sinervo. Convergent evolution of kin-based sociality in a lizard. Proceedings of the Royal Society B, 2010; DOI: 10.1098/rspb.2010.1703.)

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
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


 

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