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A Guide to the Amphibians
and Reptiles of California



Skilton's Skink - Plestiodon skiltonianus skiltonianus

Baird and Girard, 1852

(= Eumeces skiltonianus skiltonianus)
Click on a picture for a larger view



Western Skink California Range MapRange in California: Red & Gray

Blue: Coronado Skink
Gray: Intergrades


observation link





Skilton's Skink Skilton's Skink Skilton's Skink Skilton's Skink
Adult, Siskiyou County Adult, Modoc County Adult, Glenn County Adult, Santa Clara County
Skilton's Skink Skilton's Skink Skilton's Skink Skilton's Skink
Adult, Humboldt County Adult showing orange breeding color, February, Santa Clara County Underside of an adult, San Bernardino County, showing orange
breeding coloring
Skilton's Skink Skilton's Skink Skilton's Skink Skilton's Skink
Adult, San Luis Obispo County Adult with long intact tail found basking on streamside rocks in Trinity County Adult, Contra Costa County
Skilton's Skink Skilton's Skink Skilton's Skink Skilton's Skink
Adult, Sutter Buttes, Sutter County.
© Jackson Shedd.
Specimen courtesy of Eric Olson.
Breeding adult,
San Luis  Obispo County
Adult, Ventura County, © Patrick Briggs Adult, Humboldt County. When this skink was discovered hiding under an object, it ran off, jumped into the water and quickly swam to get away.
© Robert Mellinger
Skilton's Skink Skilton's Skink Skilton's Skink Skilton's Skink
Adult with breeding colors, Del Norte County © Alan Barron Adult found along the American River in Rancho Cordova, Sacramento County.
© Brandon Hunsberger
Adult found near Anza, Riverside County © Curtis Croulet
Coronado Skink      
Adult Coronado Skink, San Diego County © Jack

You can see in this distant shot how the blue tail stands out when a skink runs. The light stripes and dark background often blend into the backround with sticks and leaves rendering the head and body almost invisible, leaving people sometimes to think that they are seeing a small "neon blue" snake wriggling through the grass or leaves.
     
       
Juveniles
Skilton's Skink Skilton's Skink Skilton's Skink Skilton's Skink
Juvenile, Contra Costa County Juvenile, Napa County Juvenile, Sonoma County © Lou Silva Comparison of juvenile skinks:
Top: P. s. skiltonianus - Modoc County
Bottom: P. gilberti - Kings County
© Patrick Briggs
Greater Brown Skink      
Juvenile, Tuolumne County      
       
Breeding
Greater Brown Skink Greater Brown Skink Greater Brown Skink  
Greater Brown Skink Greater Brown Skink Greater Brown Skink  
These adult skinks (presumably a male and a female) were observed in courting behaviour at the edge of a trail in Santa Clara County. The male chased the female in and out of a crack in some bark, across the trail, and over various branches and logs.
© Wim de Groot
 
   
Identification
Skilton's Skink Great Basin Collared Lizard  
Note that the dark stripes on the sides of the tail on the Western Skink extend far onto the tail unlike the stripes on juvenile Gilbert's Skinks.   Compare

More information about the differences between Gilbert's Skinks and Western Skinks.
Western Skinks usually have 7 supralabial scales.
Compare
with Gilbert Skinks, which usually have 8 supralabials.
Toothy Skinks, genus Plestiodon, have smooth shiny cycloid scales that are reinforced with bone. Plestiodon skiltonianus is shown here.

 
Coronado Skink Coronado Skink    
The majority of Skilton Skinks - P. s. skiltionianus, have an interparietal that is not enclosed by the parietals. (from Tanner 19571 ) The majority of Coronado Island Skinks - P. s. interparietalis, have an interparietal that is enclosed by the parietals. (from Tanner 19571 )    
       
Habitat
Skilton's Skink Habitat Skilton's Skink Habitat skink habitat Skilton's Skink Habitat
Mixed coniferous forest habitat,
Santa Clara County
Rocky habitat along ridgeline in chaparral grassland,  Contra Costa County Riparian woodland/grassland Habitat, Contra Costa County Rocky mixed woodland montane Habitat, Napa County
Skilton's Skink Habitat Skilton's Skink Habitat Skilton's Skink Habitat Skilton's Skink Habitat
Habitat, coastal mixed woodlands/grasslands Monterey County

Habitat, forest clearing, Humboldt County Mixed woodland/grassland habitat next to a reservoir, Contra Costa County Streamside habitat in coniferous forest, Mendocino County (found wintering under bark on downed tree.)
Skilton's Skink Habitat Skilton's Skink Habitat Skilton's Skink Habitat Skilton's Skink Habitat
Montane habitat, 6,200 ft., San Bernardino County Habitat, 1,100 ft. Fresno County. Habitat, 2,600 ft., Trinity County
California Legless Lizard Habitat      
Sandy coastal habitat,
San Luis Obispo County
     
       
Short Videos
Skilton's Skink Skilton's Skink Tail Skilton's Skink Skilton's Skink
A skink is found under a rock. It bites hard, refusing to let go, then finally runs through dry grass with typical serpentine motion.

A juvenile skink loses its blue tail, which writhes around on the ground. This is a defensive measure used to distract the predator which caused the tail to become detached from the rest of the lizard as it tries to escape. In this video you can see how the blue tail on a juvenile skink stands out when the lizard moves, especially when it uses its stripes to blend into the vegetation. A predator is more likely to go for the tail, which can detach without hurting the lizard. A big adult skink found under a rock in winter in Contra Costa County.
lizard      
Two male Skilton's Skinks fight over territory during the breeding season on a day in early May in Skamania County, Washington. One bites the other on the head and cannot be shaken off.
© Chris Rombough
     
     
Description
 
Size
2 1/8 - 3 2/5 inches long from snout to vent (5.4 - 8.6 cm) and aproximately 7.5 inches in total length.

Appearance
A small skink with a slim body, small head, thick neck, small legs, and a smooth, shiny body with cycloid scales.
Color and Pattern
Striped with 3 dark brown and light cream stripes:
A wide dark brown stripe, edged with black, extends from the nose to the tail down the middle of the back,
bordered by two pale stripes which extend from the nose over the eye to the tail.
Two more very dark stripes extend down each side through the eyes, to the tail, where they extend well out onto the tail.
Two more pale stripes extend below these dark side stripes.
The underside is pale or gray.
The tail is gray or dull blue on older adults. Younger adults often retain some of the bright blue coloring.

During the breeding season, adults develop reddish orange coloring on the side of head, chin, on the tail, and sometimes the sides.
Young
Tail is bright blue on juveniles.
The stripes on juveniles are more highly contrasted than on adults.

Characteristics of Subspecies of Plestiodon skiltonianus   (from 1 Tanner 1957)
P. s. interparietalis - Coronado Skink

"Interparietal enclosed by the parietals in 80 per cent of the population.
Stripes of the body pattern extended onto anterior half or more of tail."

"The extension of the striped pattern on the tail is also seen in specimens of skiltonianus from the coastal ranges of California. However, specimens from north of San Diego County are generally less obviously striped on the tail and if so then with only an occasional one having the interparietal enclosed."

"Diagnosis: this form is most closely related to typical skiltonianus with which it intergrades in San Diego and Riverside counties California. It is different to all other skiltonianus in having the interparietal reduced in size and enclosed posteriorly by the parietals,
the medial and lateral dark stripes extend from the body to or beyond the middle of the tail."


P. s. skiltonianus - Skilton's Skink

"Interparietal rarely enclosed by the parietals. Usually less than 10 per cent even in Los Angeles and San Bernardino Counties; and/or stripes of body pattern not extended on more than the base of the tail."


P. s. utahensis - Great Basin Skink

"Dorsolateral stripe occupying more than half of the second scale row and being nearly one half the diameter of the dark dorsal interspace.
Dark stripe below lateral light stripe rarely present.
Diameter of the dorsolateral stripe usually greater than the length of the first nuchal."

Identifying Skinks in California - Differences between Western Skinks and Gilbert's Skinks
 
Life History and Behavior

Activity
Diurnal, but secretive and not typically seen active.
Occasionally seen foraging in leaf litter.
More commonly found underneath bark and surface objects, especially rocks, where it lives in extensive burrows.
Inactive in cold weather.
Defense
The tail is easily broken off.
When detached, it writhes back and forth to distract a predator while the lizard escapes.
The lizard will grow a new tail.
The bright blue coloring on the tail of a juvenile skink tends to distract a predator from the main body of the lizard.
Sometimes only the blue tail can be seen as the lizard rushes through grass or leaves.
Occasionally the blue tail is mistaken for a small blue snake.
Diet and Feeding
Insects, and other small invertebrates, especially spiders and sow bugs.
Breeding
Females lay 2 - 10 eggs in June and July.
Females guard their eggs until they hatch.
Eggs hatch in late July and August.

Geographical Range
In California, this subspecies is found throughout the northern part of the state, and in the northern Sierra Nevada and foothills, in the north and south coast mountain ranges, extending south to coastal San Diego County where P. s. interparietalis takes over.

It is also found in the southern Sierra Nevada on the Kern Plateau, the Greenhorn and Piute mountains, Mt. Breckenridge, Caliente Creek, and east of the Sierra Nevada in isolated locations, including the Bodie Hills, the White Mountains, and on the east slope of the Sierra Nevada at Olancha. (I saw a blue-tailed skink on the lower Kings River near Pine Flat Reservoir,and assume it was this species.)

Not present in the southern deserts and much of the central valleys. 

Also present on Santa Catalina Island. (Jones, Lawrence, Rob Lovich, 2009, shows P. s. interparietalis inhabiting Santa Catalina Island, but the Santa Barbara Museum of Natural History has a specimen from the island labelled P. s. skiltonianus, and for that reason I show P. s. skiltonianus inhabiting the island instead of P. s. interparietalis.)

The species Plestiodon skiltonianus ranges beyond California north into inland British Columbia, east into Idaho, Nevada, Utah, and northcentral  Arizona, and south to the southern tip of Baja California.

1 Tanner 1957 describes some intergrade areas: "Intergrades skiltonianus x interparietalis; San Diego Co.: Escondido; Oceanside; Poway."

Full Species Range Map
Elevational Range
From sea level up to around 8,300 ft. (2,530 meters).

Habitat
Grassland, woodlands, pine forests, sagebrush, chaparral, especially in open sunny areas such as clearings and the edges of creeks and rivers.
Prefers rocky areas near streams with lots of vegetation. Also found in areas away from water.

Notes on Taxonomy
Currently, several subspecies of Eumeces skiltonianus are recognized, including P. s. utahensis, and P. s. interparietalis.

Some taxonomists do not recognize the southern California subspecies P. s. interparietalis. They group it with P. s. skiltonianus.

Brandley et al. (2005 Syst. Biol. 54:373-390) replaced Eumeces with Plestiodon.

The Society for the Study of Amphibians and Reptiles has adopted the use of Plestiodon in the sixth edition of their Scientific and Standard English Names of Amphibians and Reptiles of North America north of Mexico list.


Jonathan Q. Richmond, and Tod W. Reeder, in their 2002 paper * list one specimem from the San Diego State University collection (SDSU 3816) utahensis CA, Inyo Co., Independence Creek at Gray’s Meadow campsite. 36 47.2N, 118 15.2W) that comes from an area fairly far south of the Nevada border on the eastern slope of the Sierra Nevada Mountains just east of Independence as E. s. utahensis, Great Basin Skink.  The Museum of Vertebrate Zoology at UC Berkeley has specimens of P. skiltionianus (with no subspecies indicated) from Inyo County including Gray's Meadow and another location east of Independence the White Mountains, and the White Mountains. If the SDSU specimen identification is correct, it is possible that this subspecies ranges in an isolated region east of Independence and in the White Mountains.


Alternate and Previous Names (Synonyms)

Eumeces skiltonianus skiltonianus - Skilton's Skink (Stebbins 2003)
Eumeces skiltonianus skiltonianus - Western Skink (Stebbins 1966)
Eumeces skiltonianus - Common Western Skink (Smith 1946)

Conservation Issues  (Conservation Status)
None
Taxonomy
Family Scincidae Skinks Gray, 1825
Genus Plestiodon (formerly Eumeces) Toothy Skinks Duméril and Bibron, 1839
Species skiltonianus Western Skink Baird and Girard, 1852
Subspecies

skitonianus Skilton's Skink Baird and Girard, 1852
Original Description
Eumeces skiltonianus - (Baird and Girard, 1852) - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 69

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

Meaning of the Scientific Name
(Eumeces - Greek - eu- good or nice and mekos length or height)
Plestiodon = ?

skiltonianus
- honors Skilton, Avery J.

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

Related or Similar California Lizards
P. g. cancellosus - Variegated Skink
P. g. gilberti - Greater Brown Skink
P. g. placerensis - Northern Brown Skink
P. g. rubricaudatus - Western Red-tailed Skink
P. s. interparietalis - Coronado Skink

More Information and References
California Department of Fish and Wildlife

1 Tanner, Wilmer W. A taxonomic and ecological study of the western skink (Eumeces skiltonianus). Great Basin Naturalist 17:59-94 1957.

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.



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. 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.

Brown et. al. Reptiles of Washington and Oregon. Seattle Audubon Society,1995.

Nussbaum, R. A., E. D. Brodie Jr., and R. M. Storm. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University Press of Idaho, 1983.

St. John, Alan D. Reptiles of the Northwest: Alaska to California; Rockies to the Coast. Lone Pine Publishing, 2002.

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

* Jonathan Q. Richmond, and Tod W. Reeder. EVIDENCE FOR PARALLEL ECOLOGICAL SPECIATION IN SCINCID LIZARDS OF THE EUMECES SKILTONIANUS SPECIES GROUP (SQUAMATA: SCINCIDAE) Evolution, 56(7), 2002, pp. 1498–1513


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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