When aliens attack

Referring to Bill McKibben's notion that nature no longer exists as a separate realm, now that the most remote wilderness has been tainted by human civilization, Burdick asks: "But if nature was finished, what now was this thing that had wrapped itself so firmly around me, doing its Sisyphean best to finish me? Was it not nature? Was I not nature? ... If the line we've drawn to distinguish natural from unnatural serves some human purpose, it is a line to which the snake -- and every living inhabitant of the world, save ourselves -- is entirely oblivious."

Something like Burdick's epiphany, his collision with the ambiguous margins of the natural world, comes to many of us, even without stalking a fearsome snake through the Guamanian jungle. A few years ago, after fumbling through a few fly-fishing expeditions, I caught my first brown trout just before sunset one evening. I was standing up to my waist in the West Branch of the Delaware River just east of Hamden, N.Y., where it's not much more than a glorified farm stream with Holstein cows chewing grass along its banks.

I had made a cast at nothing in particular with a little fly called a beadhead nymph, meant to imitate a larval insect. I was just practicing, letting the nymph drift downstream until it was time to reel it in. At the last second, when the fly was about to jerk to a stop in the water, it hung suspended in the current for a magical moment and a fish took it. Every fly fisher knows that shuddering, electrical sensation of life at the end of your line; it's that, rather than the prospect of a fish dinner, that makes the sport so addictive. (Many fly fishermen, perhaps most, don't keep or kill their catch.)

It was a young male, barely of legal size and not big enough to fight me for long. But as I guided it into my net, I was amazed at this angry little cold-water predator I had momentarily outsmarted -- despite its nondescript name, the brown trout is often golden in rivers, and spotted in black and deep orange. I thought it was the most beautiful animal I'd ever seen, as if I were its mother, or God admiring one of his sixth-day creations. Around me the river seemed intensely alive. Swallows flew from under a highway bridge as the light faded, dipping to the water. A wood duck swam past with her brood of ducklings, quacking her keep-away warning at me. Tiny riverine snails began their nightly journey upward through the forest of reeds.

Neither of us was native to that place, or entirely comfortable there. I was a weekend angler, born 3,000 miles away. The fish was probably reared in a barrel, fed Purina Trout Chow and chucked in the river by a fourth-grader. It didn't occur to me until later that one of my ancestors, in the dim European past, could have caught and eaten one of its ancestors. But there we were, and for the moment we both seemed "part of the natural world and competent to belong in it." I unhooked him and he was gone in a quarter of a second. I waded back to my car.

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