Eric Centenero Alcala
Mexican Black-tailed Rattlesnake
Crotalus molossus nigrescens
Federal and State Protections
Sujeta a Protección Especial (Pr) - Mexico
Countries of Occurrence
States or Providence
Sinaloa, Sonora, Chihuahua, Durango, Coahuila, Oaxaca, Veracruz, Tlaxcala, Zacatecas, Hidalgo, Aguascalientes, Quéretaro, Tamaulipas, San Luis Potosí, Morelos, Jalisco, Guanajuato, Nuevo León, Puebla, Nayarit
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.