My past experience with snakes has not been at all satisfying. I am afraid of them even though I recognize that my fear is irrational.

Despite that, I was thrilled to join herpetologist Robert Zumstein and my friend Jerry Lazarczyk on a search for timber rattlesnakes in western Pennsylvania. Bob and his wife, Lisa, operate Tandem Training and Tracking, a company that provides safety, educational and conservation programs related to the timber rattlesnake and other venomous species. They also work with surveyors to locate individual timber rattlesnakes in order to protect them.

I learned much about these snakes from Bob. Their world is very different from ours. Because their vision is weaker than ours, their main contact with the world is through scent, body heat and vibration. Most active at night, they are ambush predators: that is, they hunt by locating by smell small animal pathways and coiling there in wait. When the rattler senses prey of suitable size, it strikes, its fangs injecting venom. To protect itself from injury, the snake then quickly releases its prey. The poison acts quickly and the snake follows its scent trail to the dead animal, which it then slowly swallows whole. As you might expect, timber rattlesnakes have to live for long periods between meals.

Bob had scouted the areas we were to visit the day before our hikes, so few of our hours in the field were wasted. I had hiked in this area years earlier, so I was used to the vegetation of this Appalachian forest community. It differs from ours by its profusion of rhododendron, mountain laurel and sweetfern. But what best characterizes the region is its many rock outcroppings, so many in fact that Appalachian Trail hikers replace the state name with Rocksylvania. Many boots are worn out hiking here.

Where we hiked that day took us past a number of these limestone rocks and at several of them Bob searched carefully for snakes. We had walked less than a quarter mile when he pointed to the base of one of these rocks and announced the presence of two gravid female rattlesnakes, one of them already in the birthing process, having produced a single young snake, the first of up to 14.

So well-camouflaged were these snakes, however, that it took me several minutes to see them. Bob gently hooked out one of them and held it up. It was almost 5 feet long and very thick bodied, nearly black, but its rich patterns were evident. To me it was quite simply beautiful. It was still frightening, however. I kept my distance.

Despite being held up over Bob's pole, the snake was quite docile. Once I had a chance to photograph it, the rattler was carefully returned to its den and we moved on. By the end of the day, we had found several more females in similar locations.

Finally, and thrillingly, Jerry almost stepped on a handsome lighter-patterned male. To me it seemed a kind of greenish yellow. The snake retreated to a garden of ferns but Bob followed it. He was finally able to maneuver it into an open space where it coiled, its threatening head poised and its tail up buzzing away at us. The rattles were in contact with a fern stem and their shaking made the entire plant shake in turn.

This last episode represented a great conclusion to a day with dangerous snakes. But the day was even more than that. Bob is an excellent teacher and he shared not only his information about snakes but also his stories about his encounters with criminals who kill the snakes for their rattles or skins or simply for what they consider fun.

Some readers (my wife among them) urge that venomous snakes be destroyed. But the American Society of Ichthyologists and Herpetologists describes them as magnificent species, valued elements of our natural heritage, a unique component of North America's biodiversity, and one that is increasingly imperiled. Bob also pointed out that there have been no recorded deaths from rattlesnake bites since records have been kept in Pennsylvania.

In New York, where the snake is occasionally found in the Southern Tier, and Pennsylvania, the timber rattlesnake is a protected species. I join Bob in siding with the snakes.