Plateau Lizard – Tucson Herpetological Society

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Plateau Lizard (Sceloporus tristichus)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”1282″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Plateau Lizard. Photo by Robert L. Bezy and Kathryn Bolles[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1817″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Plateau Lizard. Photo by Robert L. Bezy and Kathryn Bolles[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

The Plateau Lizard (Sceloporus tristichus) is a moderate-sized (< 90 mm SVL) spiny lizard with a brown or gray dorsal background color overlain with stripes, chevrons, or crossbars. Striped morphs typically have a light dorsolateral stripe on each side, and between the two stripes are a gray mid-dorsal stripe and a row of small dark blotches or spots on either side of that mid-dorsal stripe. Background color in populations often matches the substrate. Adult males have paired blue belly and throat patches that are sometimes edged with black. The blue markings are much reduced and faint in females and juveniles. Males have enlarged post-anal scales. Hatchlings are about 25 mm SVL and resemble small females (Brennan and Holycross 2006, Persons and Leaché 2009).

The Plateau Lizard is a member of the Sceloporus undulatus complex, which includes ten species distributed across the United States and Mexico (Wiens et al. 2010). In Arizona, the complex also includes the similar Southwestern Fence Lizard (Sceloporus cowlesi), which is distributed generally to the south and east of the range of the Plateau Lizard. In southeastern Arizona, south of Interstate 10, the Southwestern Fence Lizard is also a valley species, whereas in Arizona the Plateau Lizard occurs in valleys and in the mountains. Unfortunately, where the ranges of the two species come together, both are typically striped lizards with indistinguishable patterns, and there are no morphological characters that definitively distinguish between the two. But they are genetically distinct.

The Plateau Lizard occurs across portions of central and northern Arizona, Utah except for the northwest quarter, portions of southwestern Colorado and Wyoming, and northern New Mexico (Persons and Leaché 2009). Leaché and Cole (2007) provide the best map of the distributions of the Plateau and Southwestern Fence lizards in Arizona, based on genetic analysis. From that analysis, all confirmed Plateau Lizard populations lie north of the Gila River. The farthest south populations in Leaché and Cole’s analyses are from Oak Flat between Superior and Globe, and the Pinal Mountains. The distribution extends to the northwest along the Mogollon Rim and beyond to Yarnell, the Music Mountains, northward to near Tusayan and Bitter Springs, and east to the Four Corners region. The Southwestern Fence Lizard is known to occur in the valleys of southeastern Arizona, but also above the Mogollon Rim from about 20 miles south of Sanders to near Springerville. In an area from about Holbrook to Snowflake, forms of the Plateau Lizard hybridize with the Southwestern Fence Lizard (Leaché and Cole 2007, Leaché 2011).

Lizards from the Santa Catalina and Rincon mountains are sometimes referred to as Plateau Lizards (Brennan and Holycross 2006, Flesch et al. 2010), but they could be montane populations of the Southwestern Fence Lizard. The same can be said for lizards of this complex from the Pinaleño and Santa Teresa mountains. Recognizing this problem, Bezy and Cole (2014) referred Sceloporus undulatus complex lizards from all four ranges to the Southwestern Fence Lizard, but noted there may very well be cryptic montane and lowland forms that need to be teased apart. We will have to await further genetic analysis to know whether the Plateau Lizard occurs south of the Gila River.

In Arizona, this is a species of mountains and high valleys or plateaus vegetated with grasslands, chaparral, and various montane woodland associations from oak and pinyon-juniper upslope to spruce-fir forest. In the 100 Mile Circle, it is mostly a species of montane woodlands of oak, pine-oak, and mixed conifer forests. They are often seen on rocks, but will bask on logs, trees, fence posts, and buildings (Brennan and Holycross 2006, Persons and Leaché 2009).

Plateau Lizards mate in the spring and females produce 1-3 clutches of 5-12 eggs in May through July (Persons and Leaché 2009). Eggs hatch in about two months. Mean clutch sizes from various portions of the species’ range are 6.3 (Utah), 7.2 (northern New Mexico), 7.9 (western Colorado), and 8.3 (Arizona, Smith et al. 1996). Size at maturity in those populations ranged from 53 to 59 mm SVL, and age at maturity varied from 11.5 to 22.8 months (Smith et al. 1996). Adult males defend territories with pushup maneuvers that display the blue abdominal and throat patches to other males. Population densities range from 14 to 35 per hectare. Lizards are active from about March into October, with occasional juveniles staying active into November (Persons and Leaché 2009).

This is a sit and wait predator that watches for prey and makes occasional forays from perches to capture insects and other arthropods. In the Four Corners region, ants, wasps, butterflies and moths, beetles, and flies were found in the diet of the Plateau Lizard (Douglas 1966). In southwestern Colorado, adults ate mostly grasshoppers and only 3% by weight true bugs, but the reverse was true in juveniles (Johnson 1966). In central Arizona, Plateau Lizards consumed (by volume) 22% termites, ants (9%), beetles (15%), butterfly and moth larvae (10%), and grasshopper nymphs (8%, Toliver and Jennings 1975). Small lizards are sometimes taken (Persons and Leaché 2009).

This lizard is listed as a species of least concern on the IUCN Red List. With a valid Arizona hunting license, 20 can be taken per day or held in possession, alive or dead, except in protected areas such as National Park Service units and Tribal lands. The montane woodlands where this species often occurs are vulnerable to climate change, drought, and increased wildfire, although precisely how this species might be affected is unknown. After the Lone Fire on the Tonto National Forest in 1996, Plateau Lizards increased in density (Cunningham et al. 2002). Much of the literature on this species is under the names Sceloporus undulatus tristichus, S. u. elongatus, and S. u. erythrocheilus.

Plateau Lizard (Sceloporus tristichus)

Description

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