Pretty soon, the caribou will come from over there, working their way around that low, broad mountain whose name translates to something like "where the muskrat got stuck." By late summer, as much as a third of the Porcupine herd, more than 35,000 animals, will hit the plain below the slope, their ankles clicking as they trot through tussocks of tundra that so closely match the gold and brown of their fur that they move like ghosts across the landscape. "

One time," says Gwich'in elder Dick Nukon, "I saw them crossing the river, and one caribou kept going back and forth. I saw she had a calf too small to swim. So I went and grabbed it, put it in my boat. Held it down there. Took it to the other side, and it jumped out, and I said to it, 'Don't come back when you're a big bull, or I'll have to shoot you.'"

The caribou will come from the west, where the sun hasn't set since we arrived three days ago. West is Alaska's embattled Arctic National Wildlife Refuge, but this is Vuntut National Park in Canada. Together with the even larger Ivvavik National Park directly to the north, it makes up a permanently protected area of 5,600 square miles. Beyond bureaucratic designations like "national park" and "wildlife refuge," this part of the world is best thought of as the territory of the Porcupine caribou, which circulate in a vast migratory system over two nations and hundreds of miles as they have for millennia.

And because of the caribou, these lands are also the territory of the Gwich'in people, who live in 19 villages scattered throughout the region on both sides of the border. I've been invited by the Vuntut Gwich'in to spend the end of July on the land with them. That's their phrase, "on the land"; they say it the way I say "at home." Dick can name every creek and tiny hill, and he links them in his stories like a man drawing a careful and detailed map.

But you need more than a map to get here. The only access is by floatplane, helicopter, boat, or, in winter, dogsled or snowmobile. Even where we get the helicopter, Old Crow in the Yukon Territory, is 50 miles past the middle of nowhere; Hillarie Zimmerman from Parks Canada tells me it's one of the most remote places in the whole country. It's a pretty village, 300 people living along the confluence of the Crow and Porcupine Rivers, no road out, the log-cabin-style houses decorated with antlers and satellite dishes.

Yet Old Crow is the big city compared with what happens in Vuntut. Although the Gwich'in themselves use the park as their backyard, the best estimate of annual non-Gwich'in visitors that Tourism Yukon can come up with is "maybe a handful." There is a river that's commercially rafted at the north end of the park, but most people don't know about it. A Parks Canada warden tells me that, as far as he can remember, the last non-Native, non-government worker to visit Vuntut was a guy who crashed his airplane inside its boundaries four years ago.

The GPS puts our camp at latitude 68o24'15.4" north, 100 miles above the Arctic Circle, as far north as I've ever been. When I told people I was going to the Arctic, they immediately thought I was headed into snow and ice and polar bears. But the landscape is impossibly lush. Our first days are hot and clear, with temperatures in the 80s and mosquitoes swirling in clouds so thick it's hard to see through them.

For a time, I'm able to drown out the bloodsuckers by blasting Bruce Springsteen on my iPod. Yes, I feel guilty about bringing modern sounds to this ancient, still land, but a few days of mosquito buzz is a reminder of why even the caribou can go insane up here. When the batteries finally die, the only hope is to get into the smoke from the small campfire we set up on a high spot in the creekbed.

Over the next week, our water supply will vanish bit by bit; when the helicopter sets us down, the creek is a clear, cold flow, but by the last day we're walking half a mile to get a drink.

The creek banks are lined with low willows (standard joke: "What do you do when you're lost in the arctic forest? Stand up."), and beyond that we're ringed by mountains that look as though they've been glaciated, even though they never were. In fact, during the last ice age this area was ice free, part of Beringia, a transcontinental steppe where woolly mammoths cavorted with sloths the size of compact cars.

The steppe has given way over centuries to tundra, and the great thing about tundra is that the closer you get, the more you see. At one point, I sit and count 17 plants in a square foot of land: a saxifrage, reindeer lichen, an arctic poppy, and what I think is bearberry. But my ability to name the landscape soon ends. Are these two shades of red the same plant, and is that orange tint just another phase of this emerald green? I have no words for this richness. I roll tiny leaves in my fingers, crushing them, searching for the scent of Vuntut--something like wind stirring grass in an electrical storm.

Vuntut National Park was created in 1995 not only to preserve these vital 1,677 square miles for the caribou but also, according to the park charter, to "recognize Vuntut Gwich'in history and culture and recognize and protect their traditional and current uses of the park." As their ancestors have for thousands of years, the Gwich'in hunt caribou here, set muskrat traps, and simply come out to reconnect with their past. "It makes me feel like something belongs just to us," Lance Nukon, Dick's grandson, tells me.

The park includes the wetlands of the Old Crow Flats, which support more than a hundred species of bird, including a rare subspecies of peregrine falcon and short-eared owls. (Looking down from the helicopter as we fly over the wetlands, I see owls break above tarns, but from that altitude, who knows how big their ears are?) There are even disputed sightings of the Eskimo curlew: If it's not in the park where the wetlands meet the plains and mountains, it's extinct.

And twice a year, spring and fall, Vuntut is where the caribou are as they migrate to and from their calving grounds in Alaska on the northern edge of the Arctic Refuge's coastal plain, the so-called 1002 Area.

In Whitehorse, capital of the Yukon Territory, people talk about the 1002 Area as though it were a development dispute in their suburbs. The area is a minuscule part of the refuge, a couple thousand acres, but it also happens to be the place the Bush administration is determined to drill for whatever oil it might harbor. (Those plans were temporarily thwarted late last year when the U.S. Senate successfully filibustered a bill that included Arctic drilling. Everyone expects another attempt this year.)

The oil lobby says that drilling won't affect enough land to matter, that the caribou will have plenty of space left. But the coastal plain is the prime calving ground where the caribou can get away from the mosquitoes and blackflies that plague them, a place safe from predators for the newborn calves. If it were no longer available, no one knows what the caribou would do.

Every Gwich'in I speak to has the ever-present worry that if the Arctic Refuge were opened to oil drilling, it might change or even stop the caribou migration completely, altering Gwich'in life in ways that could never be repaired. Delegations of Gwich'in and other Canadians have lobbied in Ottawa and Washington, D.C. There were protests against drilling the Arctic Refuge in Whitehorse, and Prime Minister Paul Martin came out strongly against the drilling, pointing out that it puts the Porcupine caribou herd at risk, that the economics don't make sense, and that it is simply morally wrong.

But here's the difference between the U.S. and the Canadian sides: Vuntut and Ivvavik are national parks established through Canada's settlements with Native peoples. At their creation, the Canadian government withdrew all claims to oil and mineral rights on the land. Despite a likelihood that there is oil off Ivvavik in the Beaufort Sea--the area was explored during the oil boom of the 1970s and '80s--the Canadian side of the caribou's migration route is simply not open to development.

What happens if the caribou stop coming? One night, Lance gives me his take on the issue: "We're still all tied in together. We're still coexisting. We look after the land, the animals look after us. The caribou are our whole way of survival. We never have much money, but we're always rich with caribou."

Black Fox Creek, where we are camping, is right in the middle of the caribou's migration route. The creek is a thin tributary of the Crow, which is itself a tributary of the Porcupine, which gives the herd its name. It's historically significant for two reasons. Margaret Black Fox, part of the family for whom the creek is named, was the first Vuntut Gwich'in to get a rifle. She traded wolverine skins with Inuit from Herschel Island, and that changed everything.

The Black Fox family was also the traditional owner of a caribou fence along the creek. "Owner" isn't quite the right word--"hunt master" might be better--but that's how it's explained to me by Dave Arthurs, an archaeologist sent here by Parks Canada to document the fence. There are seven known caribou fences in the park, but despite careful surveys, Arthurs says more could be waiting to be discovered.

A caribou fence uses long barrier walls to block the migration route and herd the animals into a central corral, where they can be killed and butchered relatively easily. A couple families could get together to build and maintain the structure and then reap the benefits of securing a winter's worth of meat in a fairly short time. The biggest fence found in Vuntut so far had walls that stretched nearly four miles; the biggest corral was more than 380 yards long.

According to Arthurs, the same fence line might have been used for hundreds of years, repaired by generation after generation until the introduction of rifles and the area's depopulation due to diseases brought by new settlers made the fences unnecessary.

What's left of this fence at Black Fox Creek are thin logs lying on the tundra, bleached by a hundred arctic summers. Near the corral are the remains of meat caches; antler and bone peek out from under the wood, but they're all aged in a way that forces you to look carefully to see which is which. The fence sprawls down a hillside from the corral, across a small stream, then out of sight up other hills. I climb a nearby mountain and can see how the fence line exactly follows the line of least resistance through the landscape, the path an animal would naturally take. Clearly, it was built through the genius of close observation.

Back at the camp, we have a problem: Dick can't eat much store food or he gets sick. He needs "meat"--and when people at the camp say that word, they mean fresh wild game. If it was wrapped in plastic or put on a Styrofoam tray or just bought from a shop, it's something else, not meat. Not even our caribou jerky is cutting it anymore.

On the slopes around camp, arctic ground squirrels pop out of their burrows to yell at us and do whatever squirrels do, so two of the Gwich'in kids set up snares, and by morning we have meat. They singe off the fur and gut and quarter the squirrel, dropping bits in boiling water. "It tastes just like porcupine," they tell me, then look at me with pity when I say I don't know what porcupine tastes like.

Dark turkey meat, apparently. At least that's what the squirrel leg Dick holds out to me tastes like. I'm oddly relieved that it doesn't taste like chicken.

The sun is always up. I never take my sunglasses off during waking hours and get a really interesting raccoon tan. After two days of heat, a cold wind starts to blast, gusting 60 or 70 miles an hour. Being inside the tent is like being inside a bass drum, so I walk along the sheltered streambed, stepping around fallen caribou and moose antlers, the wind moving above me. I can hear each gust coming like a train approaching.

Long before even the mammoths roamed, Vuntut was part of a great ocean, and there's evidence everywhere in the form of fossil barnacles and corals. On a rock the size of a coffee table, I find brachiopods, fossil worms an inch around and more than a foot long. As I did with the plants on the tundra, I sit in a dry part of the streambed and take a close look. I can stretch my arm and touch seven kinds of fossil.

When I get up to get a drink, I dip my hands in the cold stream. They're numb before I drink my fill, and I see tiny fish in the deeper pools.

Vuntut is so rich with life it feels like the mountains themselves are breathing. On other days, I track black spiders through the tundra. Whiskey jacks dart out of the trees along the riverbanks, and ptarmigan waddle along as though their wings were an unfair burden. Long-tailed jaegers swoop over our camp, their kite-streamer tails barely moving in the wind. A butterfly, copper and brown, stops, and I am stunned for as long as this particular blade of grass holds its interest.

Each day, I head off on my own to hike, circling the mountain behind us, where the view stretches as far as the jagged edges of the Richardson Mountains and drops down into golden valleys. I watch a lone moose walk toward a shimmering pond, and one afternoon, when the light changes suddenly, I look up to where the sun has ducked behind a cloud. There's nothing strange in that, but the edges of the cloud, and of three or four more clouds around it, have been lit by rainbows, pale red, orange, green, and blue tracing the contours like flowing water. Spend any time in high latitudes, and you learn that the Arctic is where light comes to play.

With the sun always in the sky, nobody knows what time it is; the days are marked out by hunger, and meals are occasions for more of Dick's stories.

"One time," he says, "I found two caribou with their horns locked." His hands are gnarled by repeated frostbite--he can grab the boiling kettle bare-handed--from so many winters spent hunting. "These two caribou circled around each other, but they couldn't get loose. I got a rope and tied the antlers as tight as I could, and then I got my hatchet. I hit them--I had to hit the antlers ten times before they broke free--and they just ran off." He smiles. "I would have shot the caribou, but it was too much meat."

In the end, all his stories are about the caribou. He remembers herds that were a mile long and two or three miles wide, that left behind ground so beaten down it looked like a road.

At the Old Crow airport, I had picked up a brochure titled The Vuntut Gwitchin: Their Culture & Coexistence With the Caribou, which reads, "We are grateful that the caribou come back our way, close to Old Crow every year. Sometimes they are delayed; however, we still wait patiently, because the caribou never let us down yet." T

he caribou are on their own schedule, with priorities that have nothing whatsoever to do with our lives. Thinking we should afford them the same respect and leave them this stillness, I take off on our last day on the land, heading across the now dry streambed, through a line of trees that don't even reach my thighs. The base of the mountain I make my target is a mile or so away, and it's an ankle-twisting walk at first, over foot-high tussocks that give way under each step. Finally, though, firmer soil appears, and I skirt the mountain's lower edge, crossing a pretty little stream lined with flowers the size of snowflakes.

For no good reason except the pleasure of being here, I climb halfway up the next mountain, then find a flat gray rock and sit to rest. It's silent except for the wind in the grass and the two-note call of a bird I can't see. And then, coming across the cirque at the head of the valley, eight caribou, moving quickly. In minutes, these caribou, the leading edge of the thousands that will follow over the next weeks, cross territory it took me an hour to cover.

This year, at least, the waiting is over. The migration has begun.