"We aren't fishing," I said, my lips clipping the words. My arm wanted to swing the paddle sideways, blade into his head: his eyes would blossom outwards, his skull shatter like an egg.

The corners of his mouth wilted. "Oh," he said. "Say, what part of the States are you all from? It's hard to tell, from your accent. Fred and me guessed Ohio."

"We're not from the States," I said, annoyed that he'd mistaken me for one of them.

"No kidding?" His face lit up, he'd seen a real native. "You from here?"

"Yes," I said. "We all are."

"So are we," said the back one unexpectedly. The front one held out his hand, though five feet of water separated us. "I'm from Sarnia and Fred here, my brother-in-law, is from Toronto. We thought you were Yanks, with the hair and all."

I was furious with them, they'd disguised themselves. "What're you doing with that flag on your boat then?" I said, my voice loud, it surprised them. The front one withdrew his hand.

"Oh that," he said with a shrug. "I'm a Mets fan, have been for years, I always root for the underdog. Bought that when I was down there for the game, the year they won the pennant." I looked more closely at the sticker: it wasn't a flag at all, it was a blue and white oblong with red printing, GO METS.

David and Anna had caught up with us. "You a Mets fan?" David said. "Out of sight." He slid his canoe in beside theirs and they shook hands.

But they'd killed the heron anyway. It doesn't matter what country they're from, my head said, they're still Americans, they're what's in store for us, what we are turning into. They spread themselves like a virus, they get into the brain and take over the cells and the cells change from inside and the ones that have the disease can't tell the difference. Like the late show sci-fi movies, creatures from outer space, body snatchers injecting themselves into you dispossessing your brain, their eyes blank eggshells behind the dark glasses. If you look like them and talk like them and think like them then you are them, I was saying, you speak their language, a language is everything you do.

But how did they evolve, where did the first one come from, they weren't an invasion from another planet, they were terrestrial. How did we get bad. For us when we were small the origin was Hitler, he was the great evil, many-tentacled, ancient and indestructible as the Devil. It didn't matter that he had shrunk to a few cinders and teeth by the time I heard about him; I was certain he was alive, he was in the comic books my brother brought home in the winters and he was in my brother's scrapbook too, he was the swastikas on the tanks, if only he could be destroyed everyone would be saved, safe. When our father made bonfires to burn the weeds we would throw sticks into the flames and chant "Hitler's house is burning down, My Fair Lady-O"; we knew it helped. All possible horrors were measured against him. But Hitler was gone and the thing remained; whatever it was, even then, moving away from them as they smirked and waved goodbye, I was asking Are the Americans worse than Hitler. It was like cutting up a tapeworm, the pieces grew.

We landed at the campsite and rolled up the sleeping bags and struck the tents and packed them. I covered the toilet hole and smoothed it, camouflaging it with sticks and needles. Leave no traces.

David wanted to stay and have lunch with the Americans and talk about baseball scores, but I said the wind was against us, we would need the time. I hurried them, I wanted to get away, from my own anger as well as from the friendly metal killers.

We reached the first portage at eleven. My feet moved over the rocks and mud, stepping in my own day-old footprints, backtracking; in my brain the filaments, trails reconnected and branched, we killed other people besides Hitler, before my brother went to school and learned about him and the games became war games. Earlier we would play we were animals; our parents were the humans, the enemies who might shoot us or catch us, we would hide from them. But sometimes the animals had power too: one time we were a swarm of bees, we gnawed the fingers, feet and nose off our least favourite doll, ripped her cloth body open and pulled out the stuffing, it was grey and fluffy like the insides of mattresses; then we threw her into the lake. She floated and they found the body and asked us how she got lost, and we lied and said we didn't know. Killing was wrong, we had been told that: only enemies and food could be killed. Of course the doll wasn't hurt, it wasn't alive; though children think everything is alive.

At the midway pond the heron was still there, hanging in the hot sunlight like something in a butcher's window, desecrated, unredeemed. It smelled worse. Around its head the flies vibrated, laying their eggs. The king who learned to speak with animals, in the story he ate a magic leaf and they revealed a treasure, a conspiracy, they saved his life; what would they really say? Accusation, lament, an outcry of rage; but they had no spokesman.

I felt a sickening complicity, sticky as glue, blood on my hands, as though I had been there and watched without saying No or doing anything to stop it: one of the silent guarded faces in the crowd. The trouble some people have being German, I thought, I have being human. In a way it was stupid to be more disturbed by a dead bird than by those other things, the wars and riots and the massacres in the newspapers. But for the wars and riots there was always an explanation, people wrote books about them saying why they happened: the death of the heron was causeless, undiluted.

The laboratory, he was older then. He never caught birds, they were too quick for him, what he caught was the slower things. He kept them in jars and tin cans on a board shelf back in the forest, near the swamp; to reach them he made a secret path, marked only by small notches on the trees, a code. Sometimes he forgot to feed them or perhaps it was too cold at night, because when I went there by myself that day one of the snakes was dead and several of the frogs, their skin dry and their yellow stomachs puffed up, and the crayfish was floating in the clouded water with its legs uppermost like a spider's. I emptied those bottles into the swamp. The other things, the ones still alive, I let out. I rinsed the jars and tins and left them in a row on the board.

After lunch I hid but I had to come out finally for dinner. He couldn't say anything in front of them but he knew it was me, there was no one else. He was so angry he was pale, his eyes twisted as though they couldn't see me. "They were mine," he said. Afterwards he trapped other things and changed the place; this time he wouldn't tell me. I found it anyway but I was afraid to let them out again. Because of my fear they were killed.

I didn't want there to be wars and death, I wanted them not to exist; only rabbits with their coloured egg houses, sun and moon orderly above the flat earth, summer always, I wanted everyone to be happy. But his pictures were more accurate, the weapons, the disintegrating soldiers: he was a realist, that protected him. He almost drowned once but he would never allow that to happen again, by the time he left he was ready.

The leeches were there again in the tepid pond water, clumps of young ones hanging from the lily pad stems like fingers, larger ones swimming, flat and soft as noodles. I didn't like them but distaste excused nothing. In the other lake they never bothered us when we were swimming but we would catch the mottled kind, the bad kind he called them, and throw them on the campfire when our mother wasn't watching, she prohibited cruelty. I didn't mind that so much, if only they would die; but they would writhe out and crawl painfully, coated with ashes and pine needles, back towards the lake, seeming to be able to smell where the water was. Then he would pick them up with two sticks and put them back in the flames again.