DESCRIPTION 



A robust lizard with a long, slender, cylindri- 

 cal tail, C. (G.) silus has a large head with a short, 

 blunt snout; adults measure 89 to 127 mm in 

 snout-to-vent length. The dorsal ground color is 

 gray or brown, and the dorsum has broad, distinct 

 whitish bands interspaced with dusky spots. The 

 throat has dark gray blotches. Undersides of the 

 tail and thighs are white to yellowish; during the 

 breeding season, the males are salmon or rust 

 color ventrally or all over the body except the 

 head (Erode 1978; Bury 1972; Montanucci 1965, 

 1967, 1970; Snow 1972; Tollestrup 1979). Fe- 

 males have a breeding color consisting of a single, 

 or, occasionally, a double row of red-orange spots 

 on the flanks and sides of the face and a continu- 

 ous wash of the same color on the undersurface 

 of the tail and thighs. (Tollestrup 1979). Monta- 

 nucci (1965, 1967, 1970) describes distinction in 

 color, pattern, and size between valley floor, foot- 

 hill, and ecotonal hybrid populations, but Tolles- 

 trup(1979) did not find such differences. 



RANGE 



The species occurs only in California. It was 

 once found throughout the San Joaquin valley 

 and adjacent foothills from about latitude 37°3l' 

 north southward into San Luis Obispo County. 

 It now occurs at scattered locations in the valley, 

 east to the Sierra foothills, south to the Tehachapi 

 Mountains, and along the east slopes of the Coast 

 Range foothills, including the Carrizo Plain and 

 lower Cuyama Valley (Erode 1978; Montanucci 

 1965, 1970; Snow 1972), at elevations below 

 600 m. 



RANGE MAP 



Known distribution is shown on the accom- 

 panying map (Anon 1978). 



STATES/COUNTIES 



California Fresno, Kern, Kings, Madera, Mer- 



ced, San Eenito, San Luis Obispo, 

 Santa Barbara, Tulare, Ventura. 



HABITAT 



It prefers open habitat with scattered low 



bushes, occurring on sparsely vegetated plains, 

 alkali flats, low foothills, canyon floors, large 

 washes, and arroyos; it is usually found on sandy 

 substrates and sometimes on coarse, gravelly soil 

 and hardpan (Montanucci 1965, 1970). 



FOOD AND FORAGING BEHAVIOR 



This lizard is an active predator and an oppor- 

 tunistic feeder, subsisting primarily on large 

 insects and small lizards. Montanucci (1965) re- 

 ports seasonal and regional variation in diet, 

 depending on the availability of insect and lizard 

 prey. Insects taken include locusts (Trimeratropis 

 calif ornica), grasshoppers (Melanoplus sp.), ci- 

 cadas (Okanagana triangulata, O. pallidula), 

 crickets {Acheta assimilis), and a wide variety of 

 orthoptera, lepidoptera, and coleoptera species. 

 Lizards eaten include Uta stansburiana, Phryno- 

 soma coronatum, small Sceloporus magister, and 

 Cnemidophorus tigris, as well as juveniles of its 

 own species. Small amounts of vegetable matter 

 are also taken (Montanucci 1965, 1967). Tolles- 

 trup (1979) found that C. (G.) silus feeds princi- 

 pally on grasshoppers, crickets, beetles, cicadas, 

 flies, and spiders; no vertebrate prey was found in 

 this large sample of stomachs (N = 142). 



Foraging habits vary relative to habitat and 

 available prey (Montanucci 1967). Lizards will 

 leap into the air or into shrubbery in pursuit of in- 

 sects. Stalking and pursuit are employed in 

 hunting both insect and lizard prey. Montanucci 

 (1965) reports that C. (G.) silus will dig up lizards 

 {Uta stansburiana) that have taken refuge in holes 

 or loose sand. 



SHELTER REQUIREMENTS 



Montanucci (1965) notes that population 

 densities correlate to some extent with abundance 

 of mammal burrows. Abandoned or occupied 

 burrows of kangaroo rats {Dipodomys sp) and 

 abandoned squirrel burrows [Spermophilus sp.), 

 gopher burrows {Thomomys bottae), and badger 

 dens {Taxidea taxus) are used for escape cover 

 and permanent shelter. In areas where mammal 

 burrows are scarce, adult C. (G.) silus construct 

 shallow, simple chambered tunnels under exposed 

 rocks or earthen banks. Immature lizards use 

 rock piles, trash piles, brush, etc. for temporary 

 cover (Montanucci 1965). 



