Western Skink - Plestiodon skiltonianus
The Western Skink has a shiny appearance because the body is covered in smooth and shiny, rounded scales. The dorsal coloration consists of brown, black, and golden-yellow or cream longitudinal stripes extending from the nose to the anterior portion of the tail. Younger individuals have brilliant blue tails that become progressively duller as they age. The belly is light gray to cream-colored, with a faint greenish-blue mottling. Males develop reddish-orange coloration on the chin and sides of the head during the breeding season. Adults are about 5.0 to 8.0 centimeters snout-vent length and up to 19 centimeters total length.
The Western Skink is the only lizard in Montana that appears to have a smooth and shiny body, and whose tail is blue in juveniles and young adults. Western Skinks lack a skin fold on the side of the body (present in Northern Alligator Lizards) and keeled scales (present in Greater Short-horned Lizards and Common Sagebrush Lizards). The distinct dorsal stripes of the Western Skink are not displayed by the other three species of Montana lizards. Only the Northern Alligator Lizard occurs in the range of the Western Skink in Montana.
Summary of Observations Submitted for Montana
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Records associated with a range of dates are excluded from time charts)
No information is currently available for Montana. The species is non-migratory, but there are no data on home range sizes and movements.
Little information is available. In Sanders County, Western Skinks were found in open ponderosa pine woodland in or near talus (Boundy 2001). Western Skinks were reported from Mineral, Missoula, and Ravalli counties in Agropyron spicatum-Poa sandbergii grasslands on southwest aspects (Ortega and Pearson 2001). These sites were described as gentle rolling terrain (less than 20% slope) with rocky areas imbedded, to rocky and steep terrain (average slope of 30%) with scattered ponderosa pine and Douglas-fir present. Many of the sites supported moderate to high densities of spotted knapweed (Centaurea maculosa).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
- Examining the observation records for each species in the state-wide point database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.
If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at email@example.com
or (406) 444-3655.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2001. The wild mammals of Montana. Special Publication No. 12. Lawrence, KS: The American Society of Mammalogists. 278 p.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
Wetland and Riparian Systems
Western Skinks feed primarily on insects and spiders, captives have eaten earthworms. Sometimes cannibalistic, with adults eating small juveniles (St. John 2002).
This species of lizard is found up to 2150 meters elevation in the Pacific Northwest; record elevation in Montana is 1707 m (5600 ft) in Missoula County (Maxell et al. 2009). They are diurnal and may construct burrows up to 50 centimeters long (Nussbaum 1983).
No information from Montana is currently available. Elsewhere Western Skink lays 2 to 10 eggs per clutch in a cavity under a rock or log; only a single clutch is produced per breeding season (St. John 2002, Maxell et al. 2009). Eggs are laid in June and July and hatch during late July to September; time from laying to hatching is about 30 days. Western Skink is the only native reptile in the Pacific Northwest that will stay with and guard their eggs until they hatch.
No special management activities for Western Skinks are defined at this time. Incidental survey data indicate that Western Skinks may be locally abundant in some areas of low elevation conifer forest and grassland in Montana (Ortega and Pearson 2001), even though the range of this species in the state is restricted to the far western counties. Systematic surveys of appropriate habitats for this lizard are highly desirable to establish habitat associations and preferences, periods of activity, food habits, and relative abundances in Montana. Some populations may be vulnerable to habitat fragmentation from fire, logging, rural development.
- Literature Cited AboveLegend: View WorldCat Record View Online Publication
- Boundy, J. 2001. Herpetofaunal surveys in the Clark Fork Valley region, Montana. Herpetological Natural History 8: 15-26.
- Maxell, B. A., P. Hendricks, M.T. Gates, and S. Lenard. 2009. Montana amphibian and reptile status assessment, literature review, and conservation plan, June 2009. Montana Natural Heritage Program. Helena, MT. 643 p.
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- Ortega, Y.K. and D.E. Pearson. 2001. Occurences of the western skink (Eumeces skiltonianus) in grasslands of western Montana. Northwestern Naturalist 82(3):125-126.
- St. John, A. D. 2002. Reptiles of the northwest: California to Alaska, Rockies to the coast. Lone Pine Publishing, Renton, WA. 272 p.
- Additional ReferencesLegend: View WorldCat Record View Online Publication
Do you know of a citation we're missing?
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