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Photo credit:

Kevin Hornung

Common name

Mexican Dusky Rattlesnake

Scientific name

Crotalus armstrongi

Conservation Status

Least Concern

Federal and State Protections

Range Map


Countries of Occurrence


Adult size

60cm (24in) - 68.3cm (26.9in)

States or Providence 

Jalisco, Nayarit


Species Description

This small rattlesnake species can only be found in the Trans-Mexican Volcanic Belt. It exists at elevations of 5,000 to 14,000 ft above sea level in mixed pine-oak forests. Their diet is broad and includes small mammals, frogs, salamanders, and other reptiles. Little else is known about the ecology and biology of the Mexican dusky rattlesnake.

Fun fact: This species used to be lumped in with other species in the same geographical range before genetics played a part in taxonomic research. Recently, the Mexican dusky rattlesnake was described as distinct from dusky rattlesnakes (Crotalus triseriatus) and other species. Understanding the relation of different rattlesnake species is important for their conservation and preservation!

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