A s a nuthatch worked its way headfirst down the trunk of a large silver maple in front of the house, I hardly noticed. I see that every day. Suddenly, though, the bird flared its wings, gave an alarm call, and flew off. Several feet below I noticed the source of the bird's alarm a large black rat snake. It was climbing almost straight up the trunk. I estimated its size at just under five feet in length and two inches in diameter.

      The sight made me feel good. A better mouser is hard to find. Rat snakes also eat rats, chipmunks, small rabbits, birds, and their eggs.

      My wife, however, wouldn't be so pleased. She's come a long way over the years, but she still hates snakes. She tolerates small garter, ring-neck, and green snakes (and on a good day she'll even admit that they are kind of cute), but large snakes just send her off the deep end.

      So with a big rat snake just off the front porch, I knew I had to warn her. If she discovered it on her own, she might not venture outside again until Thanksgiving.

      I called Linda onto the porch and said I had something to show her. Perhaps it was my tone of voice or maybe it was instinct, but somehow she knew. "Is it what I think it is?" she asked. She knew it was.

      It was a handsome specimen and remarkably docile. The black body glistened in the sunlight, a sign that it had recently shed its skin. (Later that day I found a large shed skin hanging from the rafters in the cellar.) Young rat snakes are mottled with blotchy patches and often misidentified (and killed) as copperheads.

      When I approached, the snake remained calm and let me pick it up. It coiled around my arm and tightened its grip. It gave me just an inkling of what a rat snake's unlucky prey must feel shortly after being surprised by this common predator.

      A rat snake bites its prey by the head or neck or whatever body part is handy and instantly wraps its body around the victim. Then it squeezes. But constrictors don't kill by crushing their prey. They suffocate it. Each time the victim exhales, the snake tightens its coils. After a few breaths, the snakes grip is so tight the prey can no longer draw a breath. Death comes quickly. Then the snake swallows its meal head first.

      But not all rats snakes are as tame as this one. Some strike repeatedly and draw blood with their many needle-sharp teeth. Others vibrate their tails ominously, perhaps duping some intruders into "recognizing" a poisonous rattlesnake. (I must confess I've been fooled by a rat snake's "rattle" a few times.) But, save for the superficial wounds from a bite, rat snakes are harmless to people.

      And it's a good thing. Rat snakes are widespread and common. Though typically found in woodlands, they often venture into old fields, farmland and barns where mice and rats abound. And you'll find them just about anywhere on leaf litter, in wood and rock piles, under logs and even in trees. Rat snakes are excellent climbers and often hunt trees and shrubs for birds and their nests. Occasionally I find one balled up inside a nest box, trapped until it digests its meal and again can slide through the hole.

      Rat snakes mate in late April or May. In June or July females lay clutches of four to 25 eggs in loose soil, sawdust pits, or compost piles. Eggs are white, oval, leathery, and about an inch-and-a-half long. Most hatch in September; young snakes measure 11 to 16 inches.

      My wife's fear of snakes is not unusual. Maybe it's their lidless eyes or their slithering habit. Maybe it's the biblical implications. Or maybe it's images from Hollywood. Regardless of the cause, our fear and persecution of snakes is unfortunate. If everyone could just learn to tolerate snakes, we'd all find fewer mice and other rodents around our homes, barns, and yards. Fortunately, that's a trade-off even Linda has managed to accept.

      Scott Shalaway lives in Marshall County where he writes about birds and nature. His syndicated newspaper column appears across the state, and he has a weekly radio program in both Wheeling and Pittsburgh.