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Photo credit:

Jesus Gordolomi

Common name

Isla Coronado/Mexican Insular Rattlesnake

Scientific name

Crotalus oreganus caliginis

Conservation Status

Least Concern

Federal and State Protections

Range Map


Countries of Occurrence


Adult size

61.9cm (24in) - 91cm (36in)

States or Providence 

Baja California


Tijuana municipality

Species Description

This dimunitive species is only found on South Coronado Island off the coast of Mexico in the Pacific Ocean!

Much smaller than its mainland cousins, the Coronado Island rattlesnake is between 2 to 3 feet long--a phenomenon known as "Insular Dwarfism", where island species exhibit smaller sizes than closely related mainland population.

This subspecies is theorized to have diverged from other C. oreganus subspecies about 0.84 million years ago. South Coronado Island is rocky with little vegetation.

This subspecies has a venom high in myotoxins, designed to quickly incapacitate prey and prevent their escape. The diet of the Coronado Island rattlesnake likely consists of more lizards and birds than that of mainland C. oreganus.

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