Montana Field Guide

Common Sagebrush Lizard - Sceloporus graciosus

The body of the sagebrush lizard is small and narrow. The back is covered with small spiny, keeled scales, and usually has a pale dorsolateral stripe on each side; scales on the rear of the thigh are very small and often granular. Dorsal coloration is brown, olive or gray with a bluish or greenish tinge. Ventral surfaces of females are white or yellow; males have blue lateral abdominal patches and blue mottling on the throat. Maximum snout-vent length (SVL) is about 6.5 centimeters; maximum total length is about 15 centimeters, with the tail length about 1.5 times the snout-vent length. Mature males have enlarged postanal scales with two enlarged hemipenal swellings on the underside at the base of the tail. Gravid females may develop a reddish-orange color along the sides. Hatchlings are 2.3 to 2.8 centimeters SVL; eggs are white and leathery, and 12 to 14 millimeters in length by 6 to 8 millimeters in breadth.

The sagebrush lizard lacks the broad flattened body and the fringe of prominent spines on each side of the body that is present in the greater short-horned lizard, the only other Montana lizard with which it overlaps in range. The northern alligator lizard has a prominent skin fold on the side of the body; the western skink has smooth and shiny rounded scales.

Montana Range

No information is currently available regarding sagebrush lizard migration patterns in Montana.

Information gathered outside the state indicates that sagebrush lizards probably move moderate distances of a few hundred meters, but dispersal distances are not well documented and home range size is small (Burkholder and Tanner 1974, Hammerson 1999).

Habitat use in Montana has not been the subject of detailed studies. However, occupied habitats appear similar to other parts of the range (P. Hendricks personal observation). This species occurs in sage-steppe habitats, sometimes in the presence of sedimentary rock outcrops (limestone and sandstone), and in areas with open stands of limber pine and Utah juniper (Hendricks and Hendricks 2002) or ponderosa pine. In many places, open bare ground is abundant, grass cover is less than 10%, and height of shrub cover may be as low as 0.25 meters.

In Yellowstone National Park, Wyoming it is found at higher elevations in geothermal areas (Koch and Peterson 1995). Favored areas tend to have a high percentage of open bare ground and a component of low to tall bushes, such as sagebrush and rabbitbrush (Stebbins 1985, Green et al. 2001). Although a ground dweller, this lizard will perch up to 1 to 2 meters above ground in low shrubs and trees (Hammerson 1999). It uses rodent burrows, shrubs, logs, and rocks for cover.

This species is an invertivore; nine orders of insects (ants, beetles, and moths the most abundant), spiders, scorpions, ticks, and mites have been reported in the diet (Hammerson 1999). Adults sometimes eat hatchling lizards.

Sagebrush lizards are active during the day in the warmer hours from early May through mid-September in Yellowstone National Park (Koch and Peterson 1995), but emerging in March or April and remaining active into October in other parts of the range (Nussbaum et al. 1983, Hammerson 1999). Timing of spring emergence has not been determined for Montana populations, but numerous animals of all size classes have been observed in the last week of September in southern Carbon County (Hendricks 1999).

In southern Utah and west-central California, the annual survival rate averaged roughly 50 to 60% in adults, but less than 30% in juveniles and eggs (Tinkle et al. 1993). The southern Utah population appeared to be substantially resource limited. Home range size averaged about 400 to 600 square meters in Utah. Areas experimentally depopulated of this species were quickly recolonized from surrounding areas (M'Closkey et al. 1997).

Use of rodent burrows for overnight refuge, escape, and winter hibernation has been documented. In southeastern Idaho, activity was determined to be unimodal with a peak at 1100 to 1500 hours (Guyer 1978). Preferred body temperature was 30.9 C. in Yellowstone National Park (Mueller 1969).

The sagebrush lizard is probably food for a wide variety of reptiles, birds, and mammals, but documented predators are surprisingly few. Predators include striped whipsnake (Masticophis taeniatus), night snake (Hypsiglena torguata), desert collared lizard (Crotaphytus bicinctores), eastern fence lizard (Sceloporus undulatus), and a variety of birds including American Kestrel (Falco sparverius), Red-tailed Hawk (Buteo jamaicensis), Loggerhead Shrike (Lanius ludovicianus), and Ash-throated Flycatcher (Myiarchus cinerascens) (Knowlton and Stanford 1942, Tinkle et al. 1993, Hammerson 1999). In Montana the Green-tailed Towhee (Pipilo chlorurus) is the only predator so far reported (Hendricks and Hendricks 2002).

There is essentially no information about the reproductive biology of this species in Montana. Juveniles (2.8 centimeters snout-vent length, 5.8 centimeters total length) have been collected in southern Carbon County in early September (P. Hendricks personal observation).

In southern Utah, reproduction occurred between mid-May and early July (Tinkle et al. 1993). Eggs are laid in June to July in Colorado, and May to July in west-central California. Extremes in clutch size are 1 and 8 eggs, but throughout the range clutch size averages between 3 and 5 eggs (Tinkle et al. 1993). Eggs hatch in 45 to 75 days (beginning in early to mid-August in Colorado and Utah, mid- to late August in west-central California). In Colorado and Utah, most adult females produce 2 clutches annually. Sexual maturity is attained in the first (south) or second (north) year (10 to 11 months in west-central California). In southern Utah, most females produce their first clutch at an age of about 22 to 24 months (some matured in about one year under uncommon optimal conditions). Males and females in southern Utah can live for at least six years (Tinkle et al. 1993).

This species is of concern in Montana due to few reports in recent years and its seemingly restricted and disjunct distribution within the state (Maxell et al. 2003), although it appears populations are robust in a few areas, such as the southern slopes of the Pryor Mountains (P. Hendricks personal observation). Reduction of sagebrush cover to promote grass growth for livestock should be avoided or carefully assessed in areas occupied by this species. When clearing of sagebrush is deemed desirable, it should be conducted in a way to retain a mosaic of cover conditions, including the presence of moderately tall shrubs (sagebrush and rabbitbrush in particular) at a relatively fine scale to accommodate habitat requirements in home ranges that are fairly small (about 400 to 600 square meters).