Tortuga Island Rattlesnake
Federal and State Protections
Special Protection - Mexico
Countries of Occurrence
59.2cm (23.3) - 105.8cm (41.6in)
States or Providence
This medium-sized rattlesnake is endemic to Isla Tortuga in the Gulf of California. It is most closely related to the western diamondback rattlesnake and is differentiated by a less distinct diamond pattern and scalation, especially on the head. Its head is also proportionally smaller, at just 3.8% of total body length, than the western diamondback (4.5% total body length).
It occurs in dry, rocky habitat, often drier than mainland Mexico, and is found everywhere on the island except the center of the volcanic crater. Its primary prey is the Dickey's mouse (Peromyscus dickeyi), the only mammal found on Isla Tortuga. Coincidentally, the mice are also absent from the center of the crater. Young rattlesnakes likely fall prey to kingsnakes (lampropeltis spp.) which also inhabit the island. Little else is known about the natural history and ecology of the Isla Tortuga rattlesnake.
C. tortugensis is reportedly abundant on the island in high densities, and locals avoid the island due to the heavy presence of rattlesnakes. Some scientists have surmised that fear (albeit misplaced) of these rattlesnakes has actually helped protect the island from human disturbance by minimizing the number of people willing to use it.