Online Field Guide to The Reptiles and Amphibians of Arizona

Black-necked Gartersnake (Thamnophis cyrtopsis), Arizona
Santa Cruz County, AZ

Black-necked Gartersnake (Thamnophis cyrtopsis), Arizona
Black-necked Gartersnake (Thamnophis cyrtopsis) Arizona
Greenlee Co., Arizona
Black-necked Gartersnake (Thamnophis cyrtopsis) Arizona
Santa Cruz Co., Arizona

 BLACK-NECKED GARTERSNAKE  Thamnophis cyrtopsis
DESCRIPTION: A medium (up to 1,070 mm or 42″ in total length) dark olive-gray snake with a single orange-yellow stripe down the middle of the back (mid-dorsal stripe) and an additional cream or white stripe along each lower side on the 2nd and 3rd scale rows (counting up from the belly). The mid-dorsal stripe is usually orange on the neck grading to pale yellow on the posterior portion of the body. Two large, jet black, crescent-shaped blotches mark the neck. The top of the head is plain gray or blue-gray. Small, black blotches mark the dark areas between the stripes on the anterior portion of the body. The underside is plain pale gray or cream. Dark bars mark the seams of the upper lip scales (upper labials). The pupils are round and the dorsal scales are keeled.

DISTRIBUTION: This snake is found across southeastern and central Arizona. An isolated population exists in the Ajo Mountains of western Pima County. In Arizona it ranges in elevation from 1,100′ in the Phoenix basin to about 7,000′ in Mogollon Rim country.

It inhabits a wide variety of biotic communities including Sonoran Desertscrub, Semidesert Grassland, Interior Chaparral, Madrean Evergreen Woodland, Great Basin Conifer Woodland, Plains Grassland, Great Basin Grassland, and Petran Montane Conifer Forest. It is usually found near water in rocky upland canyons and along semi-permanent streams and drainages. It occasionally wanders far from water.

BEHAVIOR: Although primarily diurnal and crepuscular it is occasionally active on warm nights. It is often encountered mid-morning or late afternoon foraging for tadpoles in shallow water. It hibernates during the cold months of late fall and winter.

DIET: In addition to tadpoles this snake eats frogs, toads, lizards, salamanders, earthworms, and invertebrates.

It gives birth to up to up to 25 young in late spring or summer.

By Thomas C. Brennan

Bartlett. 2000. Snakes of North America: Western
Gulf Publishing Co. Houston, TX

Brennan, T. C., and A. T. Holycross. 2006. A Field Guide to Amphibians and Reptiles in Arizona. Arizona Game and Fish Department. Phoenix, AZ

Brennan, T. C., and A. T. Holycross. 2005. A Field Guide to Amphibians and Reptiles of Maricopa County. Arizona Game and Fish Department. Phoenix, AZ

Degenhardt, W. G., Painter, C. W., and Price, A. H.. 1996. Amphibians and Reptiles of New Mexico. University of New Mexico Press. Albuquerque.

Fowlie. 1965. The Snakes of Arizona. Azul Quinta Press, Fallbrook, California

Stebbins. 1985. Western Reptiles and Amphibians. Houghton Mifflin. New York,

Black-necked Gartersnake (Thamnophis cyrtopsis) Arizona Range Map

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