Sagebrush lizard

Sagebrush lizard
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Reptilia
Order:Squamata
Suborder:Iguania
Family:Phrynosomatidae
Genus:Sceloporus
Species: S. graciosus
Binomial name
Sceloporus graciosus

The sagebrush lizard (Sceloporus graciosus) is a common species of phrynosomatid lizard found at mid to high altitudes 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 keeled and spiny scales running along its dorsal surface.

The sagebrush lizard is similar to the western fence lizard, another Sceloporus species found in the western US. The sagebrush lizard can be distinguished from the western fence lizard in that the former is on average smaller and has finer scales. 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). S. graciosus will sometimes have orange markings on its sides.

Three regional races of the sagebrush lizard are recognized: the southern sagebrush lizard lives in Southern California, and the western and northern races are found in many western states, including Oregon, Idaho, Colorado, Montana, Washington, New Mexico, Utah, Wyoming, and Arizona.

Physical description

The blue ventral patches of a male sagebrush lizard

The sagebrush lizard is usually 4.7–8.9 cm (1.9–3.5 in) snout-to-vent length (SVL) when fully grown.[2] Hatchlings are about 25 mm (0.98 in) SVL. The sagebrush lizard looks very similar to the western fence lizard, but differs in that it is typically smaller and has an increased number of scales. In appearance, sagebrush lizards are grey, brown or olive, with hints of blue or green on the dorsal surface during the light phase, and they often have irregular banding patterns on the body and tail. They also often display a black bar on the shoulder, and a light lateral and dorsolateral line on both sides. The scales on the rear portion of the thigh are small and granular, while the armpit and lateral surface of the body is often rust-colored. Females have white or yellow bellies, and males have distinctive blue patches on the abdomen and throat, although the throat patch can be absent. Males also have enlarged postanal scales, and two areas of swelling at the base of the tail. During the breeding season, males may develop orange breeding colors. Young lizards look similar to adults, but lack the dark blue markings.

Geographic distribution

The geographic range of S. graciosus includes much of the western United States. It can be found throughout Utah, Nevada, southern Idaho, northern Arizona, northwestern New Mexico, Texas, and western Colorado. It is also widely distributed throughout areas of Wyoming, Oregon, California, and Washington. Isolated populations can be found in North Dakota and Nebraska. The sagebrush lizard has been found to live at elevations ranging from 500 to 10,500 ft (150 to 3,200 m).

Habitat

True to its common name, the sagebrush lizard prefers to live in sagebrush, but is also found in pine or fir forests, redwood forests, brushlands, and piñon-juniper woodlands. They can often be found sunning on logs or sedimentary rock outcroppings, and spend most of their time on the ground, although they will climb trees to escape predators.

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. Also, the rapid escalation of proposed sand mines in Texas is an additional concern and has raised awareness among environmental groups. 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.

Behavior

The sagebrush lizard is easily frightened and will immediately seek refuge in crevices, brush, rodent burrows, rocks, or trees when alarmed. Although in rare occasions, these lizards will stay still and play dead. 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 the spring, and have larger home ranges than females, although home range size is small.

The sagebrush lizard hibernates during 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, they move into the low branches of shrubs or under vegetation. At night, on rainy days and on cool, butty days, they move underground or shelter under debris.

Sagebrush lizards eat a variety of insects, such as ants, beetles, grasshoppers, flies, hemipterans, and lepidopterans; they also eat arachnids. Western fence lizards are a chief food competitor with them in areas where their distributions overlap.[3]

Reproduction

Males defend territories both during and after the breeding season. Territorial defense is accomplished by posturing and physical combat. Male and female territories overlap, which enables the male lizards to court and mate with a few familiar females. Courtship involves headbob and shudder displays, and is physically demanding and time-consuming. Males are usually slightly larger than females. Sagebrush lizards mate in the spring, and have one or two clutches of two to ten eggs that are laid during late spring to midsummer. The eggs are laid about 1 inch (2.5 cm) deep in loose soil, usually at the base of a shrub. The eggs hatch in 45–75 days (approximately two months). Females in the northwestern range may produce two clutches. The young become sexually mature in the first (southern range) or second (northern range) year.

Predators

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

Subspecies

There are three valid subspecies of the sagebrush lizard, which differ in their geographic distributions, markings, and number of scales.[1]

  • Sceloporus graciosus graciosus Baird & Girard, 1852 – northern sagebrush lizard
  • Sceloporus graciosus gracilis Baird & Girard, 1852 – western sagebrush lizard
  • Sceloporus graciosus vandenburgianus Cope, 1896 – southern sagebrush lizard

Etymology

The subspecific name, vandenburgianus, is in honor of American herpetologist John Van Denburgh.[4]

References

  1. 1 2 "Sceloporus graciosus ". The Reptile Database. www.reptile-database.org.
  2. ↑ Stebbins 2003.
  3. ↑ Hogan 2008.
  4. ↑ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN 978-1-4214-0135-5. (Sceloporus graciosus vandenburgianus, p. 271).

Bibliography

  • Baird, S.F.; Girard, C.F. (1852). "Characteristics of some New Reptiles in the Museum of the Smithsonian Institution". Proc. Acad. Nat. Sci. Philadelphia 6: 68-70. (Sceloporus graciosus, new species, p. 69).
  • 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. 213 pp.
  • Bursey, C.R.; Goldberg, S.R. (1991). "Monthly prevalences of Physaloptera retusa in naturally infected Yarrow's spiny lizard". Journal of Wildlife Diseases. 27 (4): 710–715. doi:10.7589/0090-3558-27.4.710. PMID 1758041.
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  • 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. The University of Notre Dame. 138 (2): 418–421. doi:10.2307/2426835. JSTOR 2426835.
  • Hogan, C.M. (2008). "Western fence lizard (Sceloporus occidentalis)". GlobalTwitcher.com. Archived from the original on 2012-09-05.
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  • Montana Field Guide. "Common Sagebrush Lizard -- Sceloporus graciosus ". Mt.gov.
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  • Rose, B.R. (1976). "Dietary Overlap of Sceloporus occidentalis and S. graciosus ". Copeia. American Society of Ichthyologists and Herpetologists. 1976 (4): 818–820. doi:10.2307/1443474. JSTOR 1443474.
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  • Sears, M.W. (2005). "Geographic variation in the life history of the sagebrush lizard: the role of thermal constraints on activity". Oecologia. 143 (1): 25–36. doi:10.1007/s00442-004-1767-0. PMID 15742218.
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