Eric Centenero Alcala
Mexican Black-tailed Rattlesnake
Crotalus molossus nigrescens
Federal and State Protections
Countries of Occurrence
States or Providence
This beautiful, large rattlesnake ranges throughout most of Mexico. The Mexican black-tailed rattlesnake occurs in rocky hillsides and other montane habitats. It is active year-round but can more commonly be found during the spring and summer months around the breeding season. The diet of adults primarily consists of small mammals.
Fun fact: Juveniles and adults of this species have different venom compositions. Juveniles have a crotamine-like myotoxin which causes limb paralysis in prey; adults lack this myotoxin completely! Juveniles need this addition to their venom to help catch prey and grow in size. Adults, on the other hand, have venom that prioritizes pre-digestion.