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Sagebrush Lizard (Sceloporus graciousus)

Page history last edited by PBworks 12 years, 10 months ago

 

Sagebrush Lizard

 

(Sceloporus graciousus)

 

 

Classification:

  

Kingdom: Animilia
Phylum: Chordata
Class: Sauropsida
Order: Squamata
Family: Phrynosomatdae
Genus: Sceloporus
Species: S. graciosus
Photo obtained from  http://www.wildherps.com/species/S.graciosus.html#gracilis (9-25-07)

 

 

Introduction:

 

 There are 3 variants of the Sagebrush Lizard that have been classified by the part of the United States that they inhabit. Southern Sagebrush Lizards are found in Southern California and Northern Mexico while the Northern and Western Sagebrush Lizards inhabit most of the western U.S. and parts of the Midwest. The Sagebrush Lizard received its name from the Sagebrush plant (Artemisia tridentata) which the lizards can often be found basking near. Sagebrush Lizards are closely related to the Western Fence Lizard and the two are often difficult to tell apart. Some of the differences between the two types of lizards include coloration, size, and type of scales. Sagebrush Lizards are usually found at higher elevations compared to the Western Fence Lizard as well. In most of the Western U.S. (with the exception of Washington) the Sagebrush Lizard is thriving. In South Dakota and Nebraska Sagebrush Lizard populations are considered imperiled. The Sagebrush Lizard plays an important role in the food chain and is the prey of several types of snakes and small carnivorous mammals.  

 

 

Physical description:

 

A newborn or hatchling Sagebrush lizard is about 1 inch in length (not including the tail). Fully grown Sagebrush lizards vary widely in length from about 2 to 5 inches. Male Sagebrush Lizards have pronounced blue bellies and brown, green, grey, blue, and sometimes flecks of pink coloring on their dorsal surface. Male Sagebrush Lizards also have a larger tail base compared to females and enlarged postanal glands. Female Sagebrush Lizards are similar in dorsal coloration but usually have little or no blue on their ventral surface. Females may also develop a more vivid yellow and orange coloration on their sides during the breeding season. In physical appearance it can be difficult to tell the difference between a Sagebrush lizard and its closely related cousin the Western Fence Lizard. Three ways to tell the difference between the Sagebrush Lizard and the Western Fence Lizard are that the Sagebrush Lizard is usually smaller than the Western Fence Lizard and the Sagebrush Lizard typically does not have yellow or orange coloring on the skin of the rear limbs which the Western Fence Lizard exhibits. There are also coloration differences between the different species of Sagebrush Lizard. Below is a table that describes some of the differences.  

 

 

The Northern Sagebrush Lizard (Sceloporus graciosus) The Southern Sagebrush Lizard (Sceloporus graciosus vandenburgianus) The Western Sagebrush Lizard (Sceloporus graciosus gracilis)
The Northern Sagebrush Lizard normally has a distinct light and dark dorsolateral stripe on the dorsal surface of its body. The Southern Sagebrush Lizard has blue belly patches in males separated by a narrow dark or light colored stripe, or connected. The male Southern Sagebrush lizard also usually has black or blue coloration on its ventral surface that often joins its blue throat patch. Ventral surface of both tail and thighs are frequently blue as well.  Male Western Sagebrush Lizards have a blue throat and ventral surface patches separated by white colored areas. They also have  has less distinct striping than The Southern Sagebrush Lizard.
 

 

Male Northern Sagebrush Lizard Male Southern Sagebrush Lizard Male Western Sagebrush lizard
 photos obtained form http://www.californiaherps.com/  (9-25-07)              

  

The belly of a male Western Sagebrush Lizard
 photo obtained form http://www.californiaherps.com/  (9-25-07) 

 

Geographic Distribution & Habitat

 

As illustrated in the photo below Sagebrush Lizards inhabit a large portion of the Western United States and parts of the Midwest. The lizards preferred habitat is rocky or scattered low growing bushes but they may also be found near dried river bottoms, on sand dunes, and in evergreen forests. The Sagebrush Lizard inhabits elevations ranging from 500 to about 1100 feet. Depending on the climate they may be active from April through October.

 

 

 

 

Distribution Map: http://www.natureserve.org/explorer 

Diet:

 

The diet of the Sagebrush Lizard consists of small insects including beetles, flies, and ants. They ussually actively forage for their food in vegetation but will also forage in the open desert if needed. 

 

Predation:

 

The sagebrush lizard has several predators. Whipsnakes, night snakes, and rattlesnakes are the lizard's main predator but raptors prey on the Sagebrush Lizard as well. Small mammals like cats and badgers also prey on the Sagebrush Lizard.

 

 

Reproduction and Life Cycle:

 

 

Breeding for Sagebrush Lizards occurs in the spring. During this time the coloration of both the male and female lizards can become more vivid. Depending on the climate the female lizards will lay and bury their eggs at the base of a plant between the months of June and August. A Sagebrush Lizard clutch varies in size from 2 to 10 eggs. Lizards in the Northwest can sometimes lay two clutches of eggs in one breeding season. The life expectancy of a Sagebrush lizard is 3 to 4 years.    

 

Behavior:

 

Male Sagebrush Lizards are territorial, especially during the mating season, and defend their home range through displays (like showing their blue colored bellys) or through physical combat with other male Sagebrush Lizards. Males also tend to be more active than females and have larger home ranges. As mentioned above, Sagebrush Lizards can usually be found among rocks or near desert plants in the spring and summer. During the fall and winter they hibernate, often they do so in other animal's burrows. The sagebrush lizard is skiddish around humans and will seek the cover of rocks or occasionally climb a tree or bush when approached by humans or large animals.

 

Conservation status:

 

For the most part the Sagebrush Lizard is thriving. However, like most species, they are being affected by loss of habitat due to new housing developments, farming, and grazing. Insecticides may be affecting the amount of food that is available to the lizards as well. Below is a map of the conservation status of the Sagebrush Lizard in the states that they occupy.

 

   

 

 

 Conservation Map: http://www.natureserve.org/explorer

 

 

Scientific Article:

 

Geographic variation In the life history of the sagebrush lizard: the role of thermal constraints on activity

by: Michael W. Sears Received: 13 May 2003/ Accepted: 21 October 2004/ Published online: 30 November 2004

 

The aim of this study was to determine how the amount of time that a Sagebrush Lizard had to forage affected it's overall size and mortality due to predation. The researcher hypothesized that Sagebrush Lizards at lower and warmer elevations would grow faster (because they would have a higher thermal opportunity) but have a higher mortality (because they would be out foraging more and therefore more likely to be attacked by predators) when compared to Sagebrush Lizards that lived at a higher elevation where they would receive less daylight. To test his hypothesis the reseracher chose 3 spots in Zion National Park Utah during 1996-1999. The three sites were Clear Creek Canyon (CCC) Firepit Knoll FPK) and Gose Creek Knoll (GCK). These sites were chosen because they span the entire elevation range of the Sagebrush Lizard and they are far enough apart that there would not be any genetic flow betweenthe sites. At the sites the researcher measured the lizards snout to vent lenght (SVL) and weighed them using a scale. To try and account for mortality due to predation he also "marked" the lizards using a "unique" nail clipper.  

 

Results

 

As expected the time available for activity decreased from low to high elevatoin at the study sites. However contrary to the researchers hypothesis the Sagebrush Lizards at the highest elevation site grew the fastest despite having cooler environmental temperatures and shorter seasonal activity. Yearlings at the low and mid elevation sites were initially larger but the high elevation yearlings grew faster over the summer and fall to reacht eh same body size. The results from the study also showed the contrary to the researcher's hypothesis the Sagebrush Lizards at the higher elevation actually had a higher mortality rate than the lizards at the low and mid elevation sites. The study concluded that these results may be due to a higher degree of competition (because of higher population densities of the Sagebrush Lizards at the lower elevation sites) between sagebrush lizards for resources and competition between Sagebrush Lizards and other animals for resources at the lower elevation test sites.

 

 

References:

 

http://en.wikipedia.org/wiki/Southern_sagebrush_lizard

 

http://www.stoller-eser.com/sagebrushlizard.htm

 

http://www.wildherps.com/species/S.graciosus.html#gracilis

 

http://imnh.isu.edu/digitalatlas/bio/reptile/lacer/scgr/scgr.htm

 

http://www.reptilesofaz.com/Lizards-Subpages/h-s-graciosus.html

 

http://www.springerlink.com/content/7294awxujcfpl328/

 

http://www.californiaherps.com/ 

 

http://www.natureserve.org/explorer

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