Western Rat Snake

(Elaphe obsoleta)

Arkansas

Color Photograph: U.S. Forest Service

Texas (Eating a rat)

Color Photograph © by and courtesy of Texas Parks and Wildlife Department

Western Rat Snake (Elaphe obsoleta)

Identification: Snake 34 to 100 inches in length. Species with two color forms:

Black form: Color on back and sides black, but with some white showing around the margins of the scales. Chin white. Underside white to gray.

Blotched Form: Brown to violet-brown with irregular, darker blotches along the top of the body and with a row a irregular blotches along the side.

Scales weakly keeled and anal plate divided. Scales on the belly with their ends sharply turned upward.

Geographical Variation: None.

Range (see map on below left): Distribution delimited in the east by the Mississippi from southern Minnesota in the north to the Gulf Coast of Louisiana on the Gulf Coast. The species ranges westward into the eastern Great Plains from most of southern Minnesota in the north, southward through eastern Texas.

Habitat: The Western Rat Snake is found primarily in deciduous forest, but also occupies farmland, abandoned buildings, old fields, and swamps.

Food: Small mammals, birds, and bird eggs.

Behavior: This species is diurnal during the spring and fall, but nocturnal during the hot days of the summer. The Western Rat Snake is an excellent and prodiguous climber and is commonly found in trees and shrubs. It kills its prey by constriction.

Reproduction:  No exact data because of confusion with the Midland Rat Snake and the Eastern Rat Snake. Clutch consisting of 5 to 30 eggs. The snake mates in both the spring and in the fall. The eggs are typically laid under logs, rocks, or in leaf litter.

Note: The taxonomy for this segment of Nearctica follows, Collins and Taggart, 2007, Center for North American Herpetology, http://www.cnah.org./. Some herpetologists do not accept the division of the species formerly known at the Rat Snake into the three species Elaphe obsoleta, Elaphe spilodes, and Elaphe appalachiensis because of the arbitrary division of the distribution into three non-overlaping ranges, the lack of field characters to separate the three species, and the absence of any apparent evidence that the three species are reproductively isolated. For those who recognize only a single species, the correct name is Elaphe obsoleta.

Western Rat Snake (Elaphe obsoleta)

The three species, Elaphe obsoleta (Western Rat Snake), Elaphe spilodes (Midland Rat Snake), and Elaphe appalachiensis (Eastern Rat Snake) cannot be separated by field characters or appearance. The three species, as currently defined, are separated in the field by distribution.

Eastern Racer (Coluber constrictor)

Pine Snake (Pituophis melanoleucus)