How to Identify the Western Massasauga (Identification Guide)

Key identifying features

The western massasauga (Sistrurus tergeminus) is a small rattlesnake found across parts of the central United States, closely related to the eastern massasauga but generally associated with drier prairie and grassland habitats rather than wetlands. It shares the diagnostic nine large plate-like head scales typical of massasaugas, along with a gray body marked by dark blotches and a small, quiet rattle.

Coloration & pattern

The body is typically pale gray, tan, or light brown, marked with a row of large, rounded dark brown to blackish blotches down the back, often with additional smaller blotches along the sides creating a checkered effect. This coloration tends to be somewhat paler and more suited to open grassland camouflage compared to some other massasauga populations. The belly is usually dark, mottled with black on a lighter background.

Head, eyes & scales

The head is broad and triangular, clearly wider than the neck, with vertically elliptical pupils. Like other massasaugas, it has nine large, symmetrical scales on top of the head, distinguishing it from larger rattlesnakes that have numerous small head scales. Dorsal body scales are keeled, giving the skin a slightly rough texture.

Size & body shape

This is a small rattlesnake, with adults typically measuring 45 to 75 cm in length, similar in size to the eastern massasauga. The body is moderately thick for its length, and the rattle is small, producing a faint buzzing sound rather than a loud rattle.

Range & habitat where you'll see it

The western massasauga occurs across parts of the central United States, including areas of the southern Great Plains, favoring prairie, grassland, and open scrub habitats, often in drier conditions than those preferred by the eastern massasauga. It is frequently found basking in open grassy areas or hiding under debris and vegetation.

How to tell it apart from look-alikes

The nine large head scales, small size, and blotched gray-and-brown pattern distinguish it from larger rattlesnake species with fragmented head scales. Compared to the eastern massasauga, the western massasauga is generally associated with drier prairie habitat rather than wetlands, which can help narrow identification within its geographic range.