This small, brown snake, characterized by the strong white facial stripes and the distinctive ridge along each side of its nose, is one of the most primitive rattlesnakes found in this country.   It appears to have changed very little from its phylogenetic ancestors which migrated northward from the Sierra Madre in Mexico.   In Arizona, the ridge-nosed rattlesnake inhabits the moist pine-oak canyons of the Santa Rita and Huachuca Mountains which are often grown to alder, maple, ash and other deciduous trees.

These findings notwithstanding, the Arizona ridge-nosed rattlesnake is a unique relict species which is an important and irreplaceable part of the North American natural heritage. It may be very sensitive to major alterations of its habitat due to activities such as logging and micro-habitat destruction by snake collectors.

In the upper montane habitats, such as pine-oak and coniferous forests, the ridge-nosed rattlesnake is difficult to see among the leaf litter. It is a shy species which often remains motionless rather than rattling and revealing its presence.

If discovered, it will usually try to crawl rapidly away rather than present a defense. If restrained, it is very adept at turning and biting. The venom does not appear to be particularly potent and no human deaths from its bite are recorded.