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Photo credit:

Frank Portillo

Common name

Western Massasauga Rattlesnake

Scientific name

Sistrurus tergeminus tergeminus

Conservation Status

Overall population stable; genetically distinct populations at risk.

Federal and State Protections

Arizona Species of Greatest Conservation Need. Protected in Mexico under NOM-059-ECOL-2001.

Range Map


Countries of Occurrence

United States of America

Adult size

45.7cm (18in) - 88.9cm (35in)

States or Providence 

Arizona, Colorado, Iowa, Kansas, Missouri, New Mexico, Oklahoma, Texas


Cochise (AZ)

Species Description

The western massasauga is a small rattlesnake (albiet slightly larger than its close cousins) which occurs in the American midwest in wet meadows, marshes, and woodlands.

The diet of the western massasauga consists primarily of mammals but also snakes, lizards, birds, and frogs. Similar to other species of Sistrurus, juveniles of the western massasauga rattlesnake have a caudal lure on their tails which is a bright greenish-yellow. They more commonly use that lure to attract frogs, not lizards, as prey when they are babies! In contrast, the desert massasauga in the American southwest uses its lure for lizards, not frogs!

Their mating season is April, May, and briefly after summer.

This rattlesnake is state-threatened in Nebraska and Missouri but is not currently listed as federally threatened.

Fun fact: The specific epithet "tergeminus" comes from the Latin word meaning threefold or triple which refers to the triple row of prominent spots seen in this species.

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