Crotaphytus collaris

Collared lizards have a large head that is sometimes bright yellow. They have a long tail and two incomplete black collars around their narrow neck. Their upper side has smooth, granular scales that are turquoise to greenish to brown. Adults have many small light spots and may have yellow toes (e.g., in western Colorado). They can reach a total length of about 36 cm. 

Mature males: Two bulges from the hemipenes (male reproductive organs) may be evident at the base of their tail. Their throat is blue-green or orange, without the black center seen in the desert collared lizard. Mature males have an especially large head.

Mature females: Females have orange-red bars or spots on the sides of their body and neck during breeding season. Their throat is unmarked or faintly spotted.

Juveniles: Young have wide dark bands or rows of large, dark spots separated by narrow, light lines along their backs; they sometimes have red or orange spots on their neck and the sides of their chest.

Hatchlings: 31-42 mm in length, often about 40 mm.
 

Range extends from southeastern Utah, southern Colorado, Kansas, and central and southern Missouri south through Arizona, New Mexico, western and central Texas, Oklahoma, and Arkansas to Sonora and the north-central mainland of Mexico (Zacatecas and San Luis Potosi).
 

They prefer rocky areas with sparse vegetation, including open woodlands, bunchgrass areas, canyons, gullies, slopes, and mesa tops.
 

Eastern collared lizards are active from March or April to October in the north. The lizards that are active in fall are mostly hatchlings. The active season lasts several weeks longer in the south than it does in the north. They generally lay eggs in May, June, and July, and young usually first appear in early August.