Sagebrush lizard

Sagebrush lizard

The sagebrush lizard is a common lizard found in mid to high latitudes in the Western United States of America. It belongs to the genus Sceloporus (spiny lizards) in the Phrynosomatidae family of reptiles. Named after the sagebrush plants near which it is commonly found, the sagebrush lizard has highly keeled and spiny scales running along its back. It is a small cousin of the Western fence lizard, another Sceloporus species found in the Western U.S. Sagebrush lizards have a characteristic scalation, but the scales are smaller and finer than those found on Western fence lizards, and its markings run together to make parallel lines instead of separate dots. The keeled dorsal scales are typically gray or tan, but can be a variety of colors. The main (ground) color is broken by a lighter gray or tan stripe running down the center of the back (vertebral stripe) and two light stripes, one on either side of the lizard (dorsolateral stripes). This lizard will sometimes have orange markings on its sides.

There are 3 recognized regional variations of the sagebrush lizard; The Southern sagebrush lizard lives in Southern California, and the Western and Northern sagebrush variations are found in many western states including Oregon, Idaho, Colorado, Montana, New Mexico, and Arizona.

Physical description

The Sagebrush lizard is usually 4.7-8.9 cm in length when fully grown. Hatchlings are about 25 mm from snout to vent in length. The lizard looks very similar to the Western Fence Lizard but are typically smaller and has more scales. The lizards are grey or brown on top, usually with blotches or transverse, usually irregular, bands on body and tail. A lateral and dorsolateral light stripe (vague in some populations) present on each side. Often a black bar on shoulder. Usually rust in axilla and often on sides of neck and body. There is usually no yellow or orange on rear surfaces of limbs like the Western Fence Lizard. Blue patches on belly. Scales on back of thigh mostly granular in appearance. Young lizards have orange on neck, blue markings below subdued or absent. Males have enlarged postanal glands, swollen tail base. Blue throat with white or pink flecks, but throat patch sometimes absent. Belly patches darker blue than throat, edged with black. In light phase, blue or blue-green flecks appear in dorsal scales. In some areas males may also develop bright orange breeding colors. Females have little or no blue below, none above. When breeding, sometimes yellow below, and orange may become more vivid on neck and sides. The Northern Sagebrush Lizard (Sceloporus graciosus) normally has a distinct light and dark dorsolateral stripe on the upper sides of its body. The Western Sagebrush Lizard (Sceloporus graciosus gracilis) has less distinct striping than in preceding subspecies. It has a blue throat and belly patches in male separated by whitish areas. The Southern Sagebrush Lizard (Sceloporus graciosus vandenburgianus) has blue belly patches in males separated by a narrow strip of dark or light color, or connected. Blue or black color on belly often joins blue throat patch. Ventral surface of both tail and thighs frequently blue. Females often dusky below.

Geographic Distribution & Habitat

The lizard is commonly found in the Western U.S. and specifically in: Central and SE Washington, S. Idaho and Central and SE Montana. NW New Mexico, Northern and NE Arizona, and in Northern Baja California. It also resides in Western Colorado to the coast in Northern California, SW Oregon to the eastern slope of the Cascade mountains. There are isolated populations in North Dakota and in the mountains in Southern California, Sutter Buttes, Mount Diablo, San Benito Mountain, and Telescope Peak (Panamint Range). It typically lives in elevations between 500 to around 10,500 ft. As their name implies, Sagebrush Lizards are predominately found in sagebrush cover, but they can also be found in greasewood and other desert shrubs and sometimes on small rocky outcrops. Specifically they like manzanita and ceanothus brushland, pinon-juniper woodland, pine and fir forests, and along river bottoms in coastal redwood forests. West of Great Basin it lives chiefly in mountains, generally occurring at higher elevations than the Western Fence Lizard, but often overlapping in range at intermediate altitudes. Requirements seem to be well-illuminated areas of open ground and scattered low bushes. Chiefly a ground dweller that is usually found near bushes, brush heaps, logs, or rocks. The lizard uses rodent burrows, shrubs, logs, etc. for cover. It hibernates inactive in cold, winter weather. The duration of the inactive period varies with local climate (in Idaho, adults are active from mid-April to September, while activity of juveniles peaks in August. It is the most common lizard on Idaho sagebrush plains. In Washington, this lizard is primarily associated with sand dunes and other sandy habitats that support shrubs and have large areas of bare ground. Sagebrush Lizards bask in the morning and late afternoon. Typically, they can be seen on the ground at the edge of shrubs or other vegetation that provide cover from predators. When ground temperatures become hot, Sagebrush Lizards move into the low branches of shrubs or under vegetation. At night, on rainy days and on cool cloudy days they move underground or shelter under debris.

Diet

Sagebrush lizards eat a variety of insects, such as ants, termites, beetles, grasshoppers, flies, caterpillars, aphids, and arachnids, such as spiders, mites, ticks and scorpions. They are known to primarily eat ants.

Predators

Sagebrush lizards are important prey items for a variety of vertebrate species in the Western United States. Snakes, especially striped whipsnakes and night snakes, are the main predators of the lizard but birds of prey also consume the lizard in large quantities. Smaller carnivorous mammals and domesticated cats also prey on the Sagebrush Lizard.

Life cycle & Reproductive biology

Sagebrush lizards mate in the Spring, and have one or two clutches of two to ten eggs, laid in June-August. Typically there are four eggs per clutch which is laid in June and hatched in August. When the eggs hatch the hatchlings resemble the adults with the exception that juvenile males lack the blue ventral markings. Eggs hatch in about two months. Females in the northwestern range may produce two clutches. Young become sexually mature in the first (southern range) or second (northern range) year. The eggs are laid about 1 inch deep in loose soil usually at the base of a shrub.

Behavior

When frightened the lizard retreats to rocks, thick brush, or occasionally climbs trees. In rocky habitats it appears more agile on rock outcrops than the Western Fence Lizard. The species is easily disturbed and immediately seeks refuge in crevices, in rodent burrows, and under surface plants when alarmed. Individuals bask on the ground, on low branches of bushes, and on low boulders. Mammal burrows and rock crevices may serve as hibernation sites during cold periods. Activity is almost exclusively diurnal. The length of the warm-season activity varies geographically and from year to year, but at most localities individuals are active from March or April to late September or early October. Juveniles appear to be active later in the Autumn than adults.

Significant seasonal movement or migration has not been reported for this species. Lizards may occasionally move outside the normal area of activity to find suitable nest sites for egg-laying, or to find hibernation sites. Males are more active, especially in Spring and have larger home ranges than females. The longest overland movement for males during one year was 24 m (82 ft), while for females it was 18 m (59 ft). Males defend territories both during and after the breeding season. An area with a length of up to 7.5 m (25 ft) is vigorously defended from rival males, especially during the reproductive season. Territorial defense is accomplished by posturing and physical combat.

Interactions with humans

The Sagebrush Lizard is an easily frightened animal that seeks shelter when large animals approach. Due to this fact the lizards do not typically interact with humans. The lizards are commonly seen by hikers and mountain bikers throughout the Western U.S.

Conservation status

Loss of habitat due to agriculture, intensive grazing, and oil developments has affected the species in the shortgrass prairie badlands of North Dakota and other western states. Aerial spraying of insecticides may have also affected insect populations, the main diet of northern sagebrush lizards. Habitat loss has also increased with new residential developments in common habitats.

Subspecies

There are three subspecies of the Sagebrush Lizard in the Western U.S. All three are very similar; the differences are the geographic distribution and the subtle differences in markings. The three subspecies are the Northern Sagebrush Lizard (Sceloporus graciosus), the Sagebrush Lizard (Sceloporus graciosus gracilis), and the Southern Sagebrush Lizard (Sceloporus graciosus vandenburgianus).

Bibliography

  • Burkholder, G.L. (1973). Life history and ecology of the Great Basin sagebrush swift, Sceloporus graciosus graciosus (Baird and Girard 1852). Brigham Young Univ: Ph.D. Thesis.
  • Bursey CR, Goldberg SR (1991). "Monthly prevalences of Physaloptera retusa in naturally infected Yarrow's spiny lizard". Journal of Wildlife Diseases 27 (4): 710–715.
  • Deslippe, R.J., M'Closkey, R.T. (1991). "Experimental Test of Mate Defense in an Iguanid Lizard (Sceloporus Graciosus)". Ecology 72 1218–1224.
  • Goldberg, S.R.; Bursey, C.R. (1997). "Persistence and Stability of the Component Helminth Community of the Sagebrush Lizard, Sceloporus graciosus (Phrynosomatidae) from Los Angeles County, California, 1972-1973, 1986-1996". The American Midland Naturalist 138 (2): 418–421.
  • Martins, E.P. (1993). "Contextual use of the push-up display by the sagebrush lizard, Sceloporus graciosus". Animal Behaviour 45 (2): 25–36.
  • Rose, B.R. (1976). "Habitat and prey selection of Sceloporus occidentalis and Sceloporus graciosus.". Ecology 57 (3): 531–541.
  • Rose, B.R. (1976). "Dietary Overlap of Sceloporus occidentalis and S. graciosus". Copeia 1976 (4): 818–820.
  • Sears, M.W., Angilletta Jr., M.J. (2003). "Life-history variation in the sagebrush lizard: Phenotypic plasticity or local adaptation?". Ecology 84 (6): 1624–1634. doi:10.1890/0012-9658(2003)084[1624:LVITSL]2.0.CO;2
  • Sears, M.W. (2005). "Geographic variation in the life history of the sagebrush lizard: the role of thermal constraints on activity". Oecologia 143
  • Sears, M.W. (2005). "Resting metabolic expenditure as a potential source of variation in growth rates of the sagebrush lizard". Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology 140 (2): 171–177.
  • Sinervo, B., Adolph, S.C. (1994). "Growth Plasticity and Thermal Opportunity in Sceloporus Lizards". Ecology 75 (3): 776–790.
  • Stebbins, Robert C (2003). A Field Guide to Western Reptiles and Amphibians. 3, Houghton Mifflin.
  • Tinkle, D.W., Dunham, A.E. Congdon,J.T. (1993). "Life History and Demographic Variation in the Lizard Sceloporus Graciosus: A Long-Term Study". Ecology 74 (8): 2413–2429.

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