Crotalus helleri, commonly known as the Southern Pacific rattlesnake, is native to coastal and mountainous regions of Southern California and Baja California. It thrives in diverse habitats, from arid deserts to lush forests. Notable for its potent venom and distinct rattle, it plays a crucial role in controlling rodent populations.

Crotalus helleri, commonly known as the Southern Pacific Rattlesnake, is native to the southwestern United States and northwestern Mexico. Its distribution includes Southern California, extending into Baja California in Mexico. It is primarily found in coastal and inland regions including areas such as the Santa Monica Mountains, San Gabriel Mountains, and the coastal foothills.

The Southern Pacific Rattlesnake inhabits a variety of environments such as coastal sage scrub, chaparral, grasslands, and woodlands. It is known for adaptability to different climates, typically preferring areas with dry, rocky terrain that provide ample cover and basking spots. The climate in these regions varies from Mediterranean in coastal areas to more arid conditions inland.

Crotalus helleri is a terrestrial predator primarily feeding on small mammals, birds, and lizards. Its role as a predator helps control the populations of these prey animals, contributing to ecological balance. The species is also known to inhabit areas with a mix of open and vegetative cover, which aids in hunting and thermoregulation.