I have been trying to alter the ecology of a beaver pond, a thankless task.

The pond, on a remote and marshy piece of land, used to embrace seven acres, more or less, but the beavers grew ambitious last year and created a polder that imprisons another dozen acres downstream.

A disciplined amateur, presented with such a splendid place, would content himself with simply observing the wildlife in and around the pond and the contest between the freshwater and saltwater marsh plants for dominion over the brackish zone between the new and old dams.

But I have a passion for ducks, particularly wood ducks, which are found there at all seasons. When the local woodies leave for winter quarters in Louisiana, their places are taken by migrants from the north. I'm crazy about them not only because they're beautiful -- a drake woodie may be the most splendiferous creature in creation -- but because they are such odd ducks. They fly like bats, eat acorns and nest in hollow trees.

The pond is a great place for woodies. It's surrounded by mature forest full of oak, beech and hickory trees that supply nuts through the cold months, and brushy margins that offer perfect cover and a fine supply of bugs and plants for the ducklings.

But there aren't enough nesting trees and there are too many snapping turtles. Raccoons, squirrels and other predators wipe out four out of five wood duck nests. Most of the ducklings that survive such slaughter, and the perilous passage from tree to pond, are picked off one by one by the snappers, which lie doggo on the bottom and strike with the speed and finality of lightning.

Mother Nature doesn't recognize this as a problem. No doubt she balances her wood ducks off against her raccoons and turtles and is pleased with the results, and anyway the wood duck population has been increasing fairly steadily over the past few decades. A mature person, mindful that life comes with a short-term lease, would watch with tranquil mind as the convoys of ducklings on the pond dwindle day by day.

Like many of our species, however, I am an officious busybody who can't keep his hands off nature's intricate skein. Watching the ducklings from a photo blind, I come to recognize some of them, mostly by "personality," and give them names. When "Streak," or "Dopey" or "Bullyboy" disappears between dawn and dusk, the hen doesn't mourn or mope, because she's a natural creature and that's the natural way. But I miss the rascal, and resent the snapper that lumbers onto a muskrat house to soak up the sun and digest my little pal (who never knew me from Adam and wouldn't have cared to).

I say ducks are gentle and beautiful and snapping turtles are mean and ugly and I say to hell with the snappers and with nature's grand plan. Last spring I undertook to increase the number of wood ducks by putting up raccoon-proof nesting boxes from which the ducklings could jump straight down into the pond, cutting out a lot of predacious middlemen. Probably because the boxes reeked like brand-new army tents from the preservative I used, the ducks passed them up, and only three hens managed to bring broods to the paddling stage. Among them they had 41 of the little fluffballs, which had been reduced to nine by the time events cut short my observations. I brooded about that for a couple of months; then last weekend my man Mark and I went out to the pond to seek revenge. We put out half a dozen treble hooks on steel leaders, baited with chicken gizzards, with the lines attached to plastic bottles. The idea was that the floats would show where the hooked turtle was, without giving sufficient resistance to enable it to break off; if it has something solid to pull against, a medium-size snapper (15 to 20 pounds) can snap 80-pound-test wire leader.

Next morning, wearing chest-high waders and armed with landing net and pliers, I slogged into the pond to check the lines. The first two were undisturbed, but the third float had been hauled up into the reeds. I followed the tangled line until I saw a hump of shell. "Got one!" I shouted to Mark, who was watching from the beaver dam, "but it's just a little one."

Then I pulled harder and saw that the hump was only the head, which was the size of a softball and was mounted on a neck as thick as my forearm.

"Uh, maybe he's got me," I amended, struggling to slip the net over the thrashing, hissing creature, whose shell was within half an inch of being as wide as the mouth of the net. I was sinking in the mud, nearly at eye level with the turtle and with water slopping over the rim of the waders, when the beast lunged forward and snapped at my nose. As I ducked back, holding the line, the hook broke. I made a stab with the net to fend him off just as he lunged again, and by happy accident he wound up in the net.

Arnold Shwarzenneger could not have broken that nylon mesh, but the turtle did, getting one long-clawed foreleg free before I wrestled him to shore.

Another bait, where I had often watched a huge snapper crawl over the dam, had also been struck. Something like a quarter-acre of cordgrass had been torn up or trampled down, and a great thornbush had been pulled up by the roots. When I traced the line to the end I found that the wire leader, doubled 80-pound test, had been stretched until it parted.

One big snapper was enough to worry about at a time, I thought. When I got it home, I thought again: The shell of the one we had caught was 15 inches from notch to notch along the top, and the turtle weighed 32 pounds. The next-biggest snapper I've ever caught was 121/2 inches, and weighed 16 pounds. At that rate the big turtle in the pond, which has at least an 18-inch carapace, may weigh above 70 pounds (the record is more than 80). That would give him a head the size of a cantaloup, mounted on a neck as thick as mine. That would make a lot of good eating -- snapper is delicious, as soup, stew or kabobs -- but do I want to get into the water with such a dragon? I think I'll go back to just watching the pond, and let nature take its course.