Toothy Skinks, genus Plestiodon, have smooth shiny cycloid scales that are reinforced with bone. Plestiodon skiltonianus is shown here.
Comparison of Gilbert's Skinks with Western Skinks (Plestiodon gilberti and Plestiodon skiltonianus)
Gilbert's Skinks usually have 8 supralabial scales.
Compare with Western Skinks which usually have 7 supralabials.
Note that the dark stripes on the sides of the tail on juvenile Gilbert's skinks do not extend far onto the tail as they do on the Western Skink. Compare
More information about the differences between Gilbert's Skinks and Western Skinks.
A sub-adult Western Red-tailed Skink shows the quick serpentine movement of a small skink. Skinks are masters at diving into grass and disappearing. This video opens with the skink wriggled into some grass roots to hide.
Gilbert's Skinks, like this Western Red-tailed Skink, drop their tails to distract predators. The trick worked on me - I filmed the tail and its writhing distracting motion, some of which you can see here.
2.5 - 4.5 inches long from snout to vent (6.3 - 11.4 cm).
Tail can be up to nearly 2 times the body length.
A large skink with a heavy body, small head, thick neck, small legs, and a smooth, shiny body with cycloid scales. The tongue is forked, and is frequently protruded.
The long tail is easily detached.
Color and Pattern
Adult coloring is olive or light brown with darker edging around the scales, and sometimes the appearance of faded light and dark stripes.
Striping fades with age.
becomes orange on older adults.
Male / Female Differences
Males develop bright reddish-orange coloring on the head during the breeding season.
Females are smaller than males.
Young look very much like adult P. s. skiltonianus, with distinct light and dark stripes (which fade with age) and a blue tail. However, the dark stripe on the sides of young skinks usually extends only to near the base of the tail.
Found mostly under surface objects. Rarely found moving about on the ground in the open, however, they are active in the daytime and will occasionally be seen moving in grass, among rocks, or in leaf litter. Gilbert's Skinks are good burrowers, often constructing a shelter by burrowing under rocks and logs.
Lifespan is about 6 years or more.
Diet and Feeding
Primarily eats a variety of small ground-dwelling invertebrates, but as cannibalism has been reported, small vertebrates are probably occasionally consumed.
Adult Gilbert Skinks become reproductive in their second year of age. Not much is known about the timing of the breeding season. It varies based on location and elevation and local conditions. Mating probably occurs in late spring through early summer, most likely from April to June. Females lay a single clutch of eggs per year in summer, typically from June to August, containing from 3 to 9 eggs. The eggs are buried in loose moist soil, often under flat stones or in rotting logs. Females are thought to stay with the eggs to guard them as female Western Skinks do. Eggs probably hatch in late Summer, but hatchlings have also been observed as early as May.
Grassland, chaparral, woodlands, and pine forests. Prefers areas where moisture is present nearby.
This subspecies is endemic to California in foothills and middle elevations of the central Sierra Nevada Mountains (the Yosemite area). Also found on the San Joaquin Valley floor - probably intergrades with other subspecies.
The species Plestiodon gilberti ranges from the northern Sierra Nevada foothills from south of the Yuba River through the southern Sierra Nevada, and south through the Sacramento and San Joaquin Valleys, the coast ranges, and the southern interior and mountains, into northern Baja California. Also found in isolated regions east of the Sierras along the Nevada border and into Nevada, and in the southern tip of Nevada into western Arizona.
From sea level to 7,300 ft. (2.220 m).
Notes on Taxonomy
Four subspecies of Plestiodon gilberti are currently recognized:
P. g. arizonensis - Arizona Skink - is a fifth subspecies that was formerly recognized in Yavapai County, Arizona.
Brandley et al. (2005 Syst. Biol. 54:373-390) replaced Eumeces with Plestiodon.
The Society for the Study of Amphibians and Reptiles 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.
"Richmond and Reeder (2002, Evolution 56: 1498-1513) presented evidence that populations previously referred to Eumeces gilberti represent three lineages that separately evolved large body size and the loss of stripes in late ontogenetic stages. Although they considered those three lineages to merit species recognition, they did not propose specific taxonomic changes in that paper. We have placed the name "gilberti" in quotation marks to indicate that it refers to a group composed of several species." *
* Herpetological Review 2003, 34(3), 196-203.
"Richmond and Reeder (2002, Evolution 56: 1498–1513) presented mtDNA evidence that populations previously referred to Plestiodon gilberti represent three lineages that separately evolved large body size and the loss of stripes in late ontogenetic stages. Although they considered those three lineages to merit species recognition, they did not propose speci c taxonomic changes, and subsequently Richmond and Jockusch (2007, Proc. Roy. Soc. Lond. B 274: 1701–1708) and Richmond et al. (2011, Am. Nat. 178: 320–332) have treated them as a single species based on extensive introgressive hybridization between two of the forms and the lack of prezygotic isolation between members of all pairs of them. The results of Richmond and Reeder (2002, op. cit.) contradict the recognition of P. g. arizonensis, which is not differentiated from P. g. rubricaudatus and therefore has been eliminated from this list, and indicate the existence of an unnamed and at least partially separate lineage within P. g. rubricaudatus (their Inyo clade). " **
** Comments under P. gilberti in the Society for the Study of Amphibians and Reptiles SSAR Herpetological Circular No. 43, 2017.
Alternate and Previous Names (Synonyms)
Eumeces gilberti gilberti - Greater Brown Skink (Stebbins 1966, 2003)
Eumeces gilberti gilberti - Greater Western Skink (Smith 1946)
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.
Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018.
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.
The following conservation status listings for this animal are taken from the November 2020 California "Special Animals List" and the November 2020 "State and Federally Listed Endangered and Threatened Animals of California" list, both of which are produced by multiple agencies and available here: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. You can check the link to see if there are more recent lists.
If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can go to the NatureServe and IUCN websites to check their rankings.
There are no significant conservation concerns for this animal in California.