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A Guide to the Amphibians
and Reptiles of California





Skinks in California - Plestiodon

(formerly Eumeces)
 










observation link

 

There are Two Species of Skinks Native to California
Gilbert's Skinks, Plestiodon (Eumeces) gilberti, and
Western Skinks, Plestiodon (Eumeces) skiltonianus.

(The name of the genus of these lizards, Eumeces, was changed to Plestiodon in 2008. In most existing literature these lizards will be called Eumeces gilberti and Eueces skiltonianus.)

Appearance
Both species are small to medium-sized lizards with smooth, shiny skin. The scales are smooth shiny cycloid scales that are reinforced with bone. They are not rough and raised up like they are on some other kinds of lizards, such as alligator lizards. (Unpatterned juvenile alligator lizards are sometimes mistaken for skinks, especially the ground skink common in the East.)

Adult Gilbert's Skinks are typically brownish with no pattern and no stripes and no color on the tail (however, some adults do retain some striping and some color on the tail.)

Juvenile Gilbert's Skinks have bright blue tails in some areas, pink tails in other areas, and a combination of blue and pink or purple, in other areas.

Adult Western Skinks have alternating dark and light stripes running from the head down the length of the body. Sometimes the adults will retain some blue coloring on the tail, and the stripes on some old adults are faded.

Juvenile Western Skinks have bright blue tails, which generally fade with age. Some adults retain blue on the tail, others do not.

  skink skin  
  Toothy Skinks, genus Plestiodon, have smooth shiny cycloid scales that are reinforced with bone. Plestiodon skiltonianus is shown here.
 
     
Habitat
These skinks are generally fond of moist habitats, including rocky areas in forests and near water, but they will often be found under rocks, bark, or woody debris in areas which get direct sunlight. Sometimes they will be seen moving around in leaf litter or in grass during daylight, but usually they are secretive and hide under surface objects.

Identification of Species

Adults

Adults of both species should not be too difficult to identify.
Typically, adult Western Skinks have distinct stripes on the body, while adult Gilbert's Skinks do not.
(Some adult Gilbert's Skinks, especially females, may have some striping, but it is not as distinct as the stripes of most adult Western Skinks or as the stripes on juvenile skinks of both species.)


Juveniles

Juveniles of both species can be difficult to identify, especially in some areas.
Juvenile skinks of both species have stripes, and juvenile Gilbert's Skinks can be the same size as adult Western Skinks, which can present difficulties in differentiating juvenile Gilbert's Skinks from adult Western Skinks.


Juvenile Tail Color and Side Stripes

The presence of a pink, blue and pink, or purple tail will identify the skink as a juvenile Gilbert's Skink.

In some areas juvenile Gilbert's Skinks have a blue tail.
One way to tell them apart from Western Skinks which also have blue tails is by looking at the dark stripes on the side of the body.
The stripes on the side of juvenile Gilbert's Skinks do not extend very far past the rear legs,
while the stripes on the side of the Western Skink extend farther past the rear legs. Compare

(However, it has been shown that the use of this side stripe characteristic is not accurate in some areas of the state.
See the notes below.)

Scale Count Differences
A Western Skink usually has 7 supralabial scales and 4 enlarged nuchal scales.
A Gilbert's Skink usually has 8 supralabial scales and 3 enlarged nuchal scales.

(Powell, Collins, and Hooper 1998)
skink skink skink
Western Skink - Plestiodon skiltonianus - usually has 7 supralabial scales.
skink skink skink
Gilbert's Skink - Plestiodon gilberti - usually has 8 supralabial scales.
This is not always the case, as you can see on the lizards below.
skink skink  
Gilbert's Skink Western Skink  
 
Juvenile Skinks in California
skink skink whiptail
Juvenile Gilbert's Skink

Stripes on the sides of the tail do not extend far past the rear legs. Compare
Be careful not to confuse juvenile Belding's Orange-throated Whiptails, like the one seen above, with juvenile blue-tailed skinks. This whiptail has more light stripes on the back, and is thinner, with a longer and thinner tail.
skink skink skink
Adult Western Skink

Stripes on the sides of the tail extend far past the rear legs. Compare
Beware that the side stripes of adult Western Skinks with tails that have been re-grown may not continue very far past the rear legs, as you can see here.
skink skink skink
Juvenile Western Skink with blue tail. Juvenile Gilbert's Skink with pink tail. Juvenile Gilbert's Skink with blue tail.
skink skink skink
Older juvenile Gilbert's Skink
with a blue and pink tail.
Older juvenile Gilbert's Skink
with reddish tail.
Skinks in Southern California can be confused with the Orange-throated whiptail, but the whiptail will have more light stripes and they are thinner. Click the picture above for a closer comparison.
     
Gilbert's Skinks - Plestiodon gilberti
skink skink skink
Large adults with no distinct stripes. Often, the scales appear outlined with dark coloring.
skink skink skink
Adult males in breeding condition develop bright red on the head and tail. This color fades after the breeding season is over.

Adults in some areas retain faint stripes, but they are not as distinct as those of the Western Skink.
   
Four subspecies of Gilbert's Skinks occur in California.
The taxonomy of Gilbert's skinks is under revision, meaning that the names of the subspecies not be valid and will probably change in the near future.

If you want to find which subspecies is found in your area, check the map below.
Click on the name links for more pictures and information.

map
Range:

Orange: Variegated Skink - Plestiodon gilberti cancellosus

Blue: Greater Brown Skink - Plestiodon gilberti gilberti

Purple: Northern Brown Skink - Plestiodon gilberti placerensis

Red: Western Red-tailed Skink - Plestiodon gilberti rubricaudatus

Gray: Approximate intergrade areas
 
Western Skinks - Plestiodon skiltonianus
skink
skink
skink
  Adults with bright blue on the tail.  
skink skink skink
  Adults with little or no blue on the tail.  
skink
skink
skink
Adults in breeding condition develop a reddish wash on the head, throat and tail, and sometimes on the side. This color fades after the breeding season is over.

Two subspecies of Western Skinks are currently recognized. There is no easy way to tell them apart. In fact, some herpetologists do not believe that these subspecies are valid.

If you want to find which subspecies is found in your area, check the map below.
Click on the name links for more pictures and information.

map
Range:

Blue: Coronado Skink - P. s. interparietalis

Red: Skilton's Skink - P. s. skiltonianus

Gray: Intergrade area
 

Notes 

In a 2013 paper 1, Shedd and Richmond presented data that shows that the use of the side-stripe length to differentiate the two species is not accurate in all areas: "However, like the other characters used to differentiate P. skiltonianus and “gilberti,” we have detected notable variation in the extension of the lateral tail stripe in populations of both species, and below we present data that describe how the character fails to differentiate the two in certain parts of the range." ... "Because of the variability of this character across the range of the species complex, we consider it unreliable for distinguishing P. skiltonianus and “gilberti” over large portions of the range of the P. skiltonianus complex "

They also point out areas in which a blue tail can indicate either species: ' “...gilberti” populations in the northern and central Sierra Nevada, as well as in scattered populations in the east Mojave Desert and the Panamint Mountains, are blue-tailed.'

References
1  Jackson D. Shedd and Jonathan Q. Richmond. Herpetological Review, 2013, 44(3), 417–420.  Conserved Ontogeny of Color Pattern Leads to the Misdiagnosis of Scincid Lizards of the Plestiodon skiltonianus Species Complex © 2013 by Society for the Study of Amphibians and Reptiles)

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

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

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

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

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