‹ Compare two snakes
Prairie Rattlesnake vs Western Massasauga
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Scott Shupe, no rights reserved
Prairie Rattlesnake
Crotalus viridis
Venomous(c) Meghan Cassidy, some rights reserved (CC BY-SA)
Western Massasauga
Sistrurus tergeminus
VenomousThe quick way to tell
Look at the top of the head. The Western Massasauga has nine big, plate-like scales there. A Prairie Rattlesnake's crown is covered in many small scales.
Head ★ This settles it
Broad triangular head, clearly wider than the neck, with two pale diagonal stripes on the cheek.
Triangular head with nine large, plate-like scales on top — unlike most rattlesnakes, which have many small scales there. A white-edged dark stripe runs from the eye to the jaw.
Pattern
Pale-edged blotches tightening into bands near the tail; colour matches local soil.
Rows of dark brown blotches on gray or tan, with smaller spots along the sides.
Eyes
Vertical slit pupil; heat-sensing pit between eye and nostril.
Vertical slit pupil; heat-sensing pit between eye and nostril.
Pits
A deep heat-sensing pit on each side of the face, between the eye and the nostril.
A deep heat-sensing pit on each side of the face, between the eye and the nostril.
Tail
Thinner than the body; tail rings dull, not bold black and white, ahead of the rattle.
Banded light and dark ahead of a small rattle; babies have a yellowish tail tip.
What it does
Coils and rattles loudly; holds ground rather than fleeing.
Usually lies still when approached; some rattle at the least disturbance and strike.
Where it lives
Great Plains from southern Canada through Montana, the Dakotas, Wyoming, Nebraska, Kansas, Colorado, western Oklahoma and west Texas, west into eastern Idaho, eastern Utah, New Mexico and northeastern Arizona.
Central plains from southwestern Iowa, northwestern Missouri and southeastern Nebraska south through Kansas and Oklahoma into Texas, and west into Colorado, New Mexico and far southeastern Arizona.