Western Fence Lizard

Contents:
 
Links:
Taxon, Status, and Ranks Habitat Photos
General Description State Status Comments
Identification Tips Inventory & Research Needs Key Features
Phenology Threats & Mgmt Concerns
Range References Distribution Map

Taxon, Status, and Rank

Species Sceloporus occidentalis     Baird & Girard, 1852
Family Phrynosomatidae
(North American Spiny Lizards and allies)
Status None
State Rank S5
Global Rank G5

General Description

This is a medium-sized gray, brown or brownish-black lizard with keeled, spiny scales dorsally and two rows of light and dark markings down the back. Largely based on temperature, individuals can lighten or darken considerably; when individuals darken, dorsal markings become difficult to see. Adults range in size from 5.6 – 8.7 cm (2.2-3.4 in.) snout-vent length. Blue patches exist on the sides of the abdomen and on the throat, and the keeled scales on the posterior surface of the thighs are yellow. These blue patches may be faint or lacking in females. In males, the blue coloration is more extensive and intense, and the abdominal patches typically have a medial lining of dark black. This coloration intensifies with age. Males also have scattered blue spots on selected scales on the back, enlarged post anal scales and a swollen tail base. Hatchlings and juveniles are similar in appearance to adult females but usually have lighter and more contrasting dorsal coloration. See Photos Page.

Identification Tips

Sagebrush Lizards are smaller (adults less than 60 cm snout-vent length), less robust, have orange- or rust-colored axilla (arm-pits), lack yellow coloration on the posterior surface of the thighs and the spiny dorsal scales are smaller than in Western Fence Lizards. In Washington, female and juvenile Sagebrush Lizards completely lack blue patches. In males, the blue patches on the abdomen are not edged in black and the throat patch is a blue and white mosaic, not solid. Because the dorsal scales are smaller, it is possible to run a finger from the tail to the head, against the scales, without catching on the scales of a Sagebrush Lizard but not Western Fence Lizard. The Side-blotched Lizard is smaller, has fine granular scales dorsally, a gular fold (a fold of skin at the throat) and a black spot on the side of the body behind the forelimbs. See Key Features Page.

Phenology

Activity in Washington varies depending on the location of the population. In the Puget Sound, where the climate is mild, activity starts in March. Individual lizards may be active on sunny warm days even earlier. In eastern Washington, activity is typically delayed until April and continues into October. Mating and egg laying behavior has not been described for Washington. Hatchlings appear in August and September in eastern Washington.

Range

The species occurs in three discontinuous ecoregions: Puget Trough, East Cascades and the Blue Mountains. A few records also exist on the western edge of Okanogan Ecoregion.

In the Puget Trough Ecoregion, observations are limited to marine shorelines and nearby uplands, both on the mainland and in island localities. Exceptions include a 1947 museum record from Manitou in Pierce County and recent observations of lizards near Chambers Creek in Pierce County. The population at Larabee State Park in Whatcom Co. is introduced.

Two isolated records exist in the Columbia Basin: a 1947 museum record from Dry Falls in Grant Co., and an old museum record from Cheney in Spokane Co. Western Fence Lizards have not been reported from these areas or any other area in the Columbia Basin except for these two specimens. Though the collectors were both experienced herpetologists, these specimens should still be checked to make sure that they were correctly identified. See Distribution Map.

For information on the complete range of this species, see NatureServe Explorer.

Habitat and Habits

In the Puget Trough, they occur along shorelines with accumulations of driftwood. They have also been found in sunny, rocky areas, as well as an oak stand with rubbish piles, along Chambers Creek in Pierce County. East of the Cascades and in the Columbia gorge, they primarily occupy dry forests, such as Oregon-Oak and Ponderosa Pine, but also occur in non-forested habitats such as bitterbrush-grassland and grasslands. On occasion, they have been observed in clear-cuts and other openings in more heavily forested areas on the edge of their range. In treeless habitats, they tend to be associated with rocks, rock outcrops or other features that allow them to climb above the vegetation to bask and watch for prey, and in the case of males, defend territories and attract females. They are excellent climbers and will escape up trees or scamper around rock faces when approached. They are usually common where they occur. At night and when conditions are cool or rainy, they shelter under rocks and logs.

State Status Comments

Western Fence Lizards are common in Washington and conservation concerns are limited to protection of the relatively small number of populations associated with upper beach driftwood accumulations in the Puget Trough Ecoregion. Some of these populations could be lost to bulkheading and bank stabilization projects that seek to create home sites along the desirable Puget Sound shoreline. Loss of oak prairie habitat due to succession and invasion of exotic shrubs, especially Himalayan blackberry (Rubus discolor) and Scotch broom (Cytisus scoparius), may have contributed to their decline in the Puget Trough Ecoregion.

Inventory and Research Needs

Inventory is needed in the Puget Trough and Blue Mountain ecoregions to determine the current distribution and status. Observations can be submitted to the WDFW herp database by contacting Lori Salzer at salzeljs@dfw.wa.gov.

The pattern of loss of oak habitat in western Washington is generally acknowledged, but unstudied in context of egg-laying reptiles that may require well insolated ground in which to deposit their eggs. The Western Fence Lizard is one of five egg-laying reptile species that was historically presumably associated with oak prairie habitat on a wider scale; study of the habitat required for its terrestrial nest would provide significant insight into its management needs.

Threats and Management Concerns

Potential for loss of Puget Trough shoreline populations to bulkheading and bank stabilization projects. An unknown level of loss may have resulted from the succession and invasion of oak prairie habitat by shrubs.

References

Hallock (1999c), Nussbaum et al. (1983), Stebbins (1985)

 

Personal communications: H. Brown, M. Hayes




Hallock, L.A. and McAllister, K.R. 2005. Western Fence Lizard. Washington Herp Atlas. http://www1.dnr.wa.gov/nhp/refdesk/herp/

Last updated: February 2005


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