Great Basin Fence Lizard, Sceloporus occidentalis longipes

Great Basin Fence Lizard, Female, Sceloporus occidentalis longipes. Lizard photographed at the San Diego Botanic Garden. Encinitas, California, August 2015. Length: 18 cm (7.1 inches). Identification courtesy of Gary Nafis, CaliforniaHerps.com.

Great Basin Fence Lizard, Sceloporus occidentalis longipes. Photograph taken within the greater Palm Springs area of southern California, March 2021. Photograph courtesy of Dr. Tom Bartol, Carlsbad, California. Identification courtesy of Gary Nafis, Californiaherps.com.

The Great Basin Fence Lizard, Sceloporus occidentalis longipes, is a member of the Phrynosomatidae family of Zebra-tailed, Fringe-toed, Spiny, Side-blotched and Horned Lizards. The Phynosomatidae family consists of more than one hundred twenty members placed in nine genera. There are ninety species in the Sceloporus genus. The Great Basin Fence Lizard is one of six subspecies of Western Fence Lizards. The Great Basin Fence Lizard is known in Mexico as Lagartija-Escamosa Del Occidente.

Great Basin Fence Lizards are fairly small and brown, gray, or black in color with narrow irregular crossbars. Their color often appears completely black, especially on dark-phase lizards that have not completely warmed up. Some possess light markings on their sides and back that form stripes or irregular lines, and sometimes dark blotching may form irregular bands. Their throat and underside are typically pale to dark gray in color. They have keeled and pointed scales of equal size on their back and sides. The scales on their thighs are abruptly smaller and mostly keeled. The rear surfaces of their limbs are typically yellow or orange in color. Sexual dimorphism is displayed with males possessing blue markings on the sides of their belly edged in black, a single blue patch on their throat, and a swollen tail base. Females have a plain belly or one with faint blue markings, no blue or green color on their dorsal surfaces, and dark bars or crescents on their back. Juveniles have little or no blue color on their throat and their bellies are either plain or have faint blue markings. Great Basin Fence Lizards reach a maximum of  10 cm (3.9 in) in length from snout to vent and 18 cm (7.1 inches) in total length.

Great Basin Fence Lizards are highly territorial and males establish and defend territories that contain elevated perches, where they can observe potential rivals and mates. Males defend their territory and attempt to attract mates with head-bobbing and push-up displays that expose their blue throat and ventral colors. Additionally, males will defend their territory by engaging in  physical combat with other rival males. Mating occurs in early to late spring, depending on the elevation, from March to June. Gestation lasts approximately 2 to 4 weeks. Females dig small pits in loose, damp soil where they lay 1 to 3 clutches of 3 to 17 eggs, usually from May to July. Eggs hatch after about 60 days, typically from July to September. Hatchlings measure about 2.5 cm (1.0 inches) in length and receive no parental care. Juveniles become sexually mature in the spring of their second year. Great Basin Fence lizards have lifespans of five to seven years in the wild.

Great Basin Fence Lizards are diurnal, often seen basking in the sun on rocks, downed logs, trees, fences, and walls. They prefer open, sunny areas and are active when temperatures are warm. During periods of extreme heat or cold they become inactive, sheltering in crevices or burrows and under rocks, boards, and tree bark. They are likely active all year in parts of their range where temperatures are favorable and there is adequate sun for basking. Great Basin Fence Lizards consume small, mostly terrestrial, invertebrates such as crickets, spiders, ticks, and scorpions. Occasionally, they will eat small lizards including their own species. They have the ability to easily detach their tails to distract potential predators. The detached tail wriggles on the ground, drawing attention away from the body of the lizard and allowing them time to escape. Broken tails do grow back, however, the regenerated tails are often not as long as the original. Many Great Basin Fence Lizard populations are commonly plagued by Western Black-legged Ticks, Ixodes pacificus. This species of tick is a primary carrier of Lyme disease. However, a protein in the lizard’s blood kills the bacteria that causes Lyme Disease. 

Great Basin Fence Lizards occupy a variety of open, sunny habitats including woodlands, grasslands, desert scrub, chaparral, forests, along waterways, and suburban dwellings. They prefer places with suitable basking and perching sites such as fences, walls, woodpiles, piles of rocks and rocky outcrops, dead and downed trees, and open trail edges.

The Great Basin Fence Lizard may be confused with Common Sagebrush Lizards (black mark on their sides cranial to their front legs, and occasionally possess a rusty coloring caudal to their front legs; smaller dorsal scales and gray granular scales on their rear thighs, unlike the yellow-orange keeled scales found on Great Basin Fence Lizards).

From a conservation perspective all Western Fence Lizard species are included in one listing and the exact status of this subspecies is unclear. Western Fence Lizards are currently considered to be of Least Concern due to their wide distribution, tolerance of a broad range of habitats, and presumed large population size. They are one of the most commonly seen lizards in California due to their abundance in populated areas and their conspicuous behavior. No major threats have been identified for this species. Note: the taxonomy of Sceloporus occidentalis is currently under review with controversy surrounding the establish six subspecies: the Coast Range Fence Lizard, Sceloporus occidentalis bocourti, the Great Basin Fence Lizard, Sceloporus occidentalis longipes, the Island Fence Lizard, Sceloporus occidentalis becki, the Northwest Fence Lizard, Sceloporus occidentalis occidentalis) the San Joaquin Fence Lizard, Sceloporus occidentalis biseriatus, and the Sierra Fence Lizard, Sceloporus occidentalis taylori.