Sam Fried Sam FriedSam Fried has seen and photographed almost all North American birds. Meet Sam Previous Answers

By “most deadly” I gather Sean is thinking about people as the target, in which case there is one clear-cut answer. The western rattlesnake is the only venomous snake found in Montana. The prairie rattlesnake, a distinct race, or subspecies of the western rattler, is distributed throughout Montana east of the Rocky Mountains.

It is by and large a snake of semi-arid grasslands and mountain foothills, and seldom seen at elevations above 8,000 feet. Western rattlesnakes favor rocky, broken terrain, where they inhabit crevices and ledges, abandoned rodent dens, and the shady entrances of caverns. They prey upon mice, ground squirrels, prairie dogs, and rabbits, and locate their meals with heat-sensing nerves. A large western rattlesnake reaches four feet; the prairie race is generally smaller, say between two and three feet in length.

With its retractable, hollow fangs, the western rattlesnake injects its victims with blood-destroying venom when it bites. Unlike other venomous snakes in the US, however, people bitten by this species rarely die; nausea, along with soreness and pain in the area of the bite, are the most common outcome. Like any snake, the western rattler will opt for a quick exit every time. Upon hearing (or more accurately feeling) the footsteps of an approaching person, the snake will disappear. If it feels threatened it will coil itself and rattle; this is your cue to exit.

Though it is fairly common in appropriate habitats, the western rattlesnake is reclusive. In nearly ten years of hiking, hunting, and fishing throughout a good deal of snake territory, I've encountered just one or two. Both were surprise encounters for me and the snakes; both stood their ground and rattled, and I moved on.

As far as predators, a Western rattlesnake's most enthusiastic enemy is people. A great many rattlesnakes are killed immediately on sight by landowners, particularly ranchers concerned about the welfare of their livestock. Their fear is understandable, though rattlesnakes occupy an important and worthwhile role in maintaining stable rodent populations.