PROLOGUE

We were surrounded. Waves of thick fog blew over the thirty-kilometre-­wide plain separating us from the Arctic Ocean, and in the intermittent clearings I glimpsed more and more grizzly bears. A big male slept on the opposite side of the canyon, two adults nosed into the mist toward me, and two hundred metres farther away, a mother with newborn cubs angled for the beach where we’d landed the rafts. I jabbed at the rusty siding of the Water Survey cabin where we’d taken refuge, then yanked at the steel mesh bolted over the two small windows. Solid. Judging from the muddy paw prints smeared across every outside wall, the small tin building in the middle of the open tundra had survived probing, rubbing bruins before. But I gave the hinges and handle of the door a good tug as I stepped inside, just in case.

“Five more bears,” I said, shaking the rime from the hood of my parka.

Steve looked up from the cloud of steam coming from the pot of noodles on the small camp stove and cupped a hand over his ear.

“Five more bears,” I repeated, trying not to sound too surprised. I ­didn’t know what was normal here. It was my first patrol down the Firth River and my first year as a seasonal warden in northern Canada’s remote Ivvavik National Park. Steve Travis, on the other hand, was a seven-­year veteran in the area and had made the 130­kilometre-­long trip by raft down the Firth’s twisting canyons more than thirty times. I searched his face for a reaction, but he only pulled on his wool hat and slipped out the door. It was 11:00 pm and dinner would have to wait.

The fog was beginning to lift, and by the time we scrambled onto the roof to look around, we could see seven bears, as well as half a dozen golden eagles wheeling in and out of the rising clouds. I trained my binoculars on the farthest grizzly, a dark-­coated animal with a hitching limp, and as I did, something on the slope behind it moved. While I fiddled with the focusing ring I saw a tuft of grass slide sideways. A bush drifted downhill. Suddenly the whole slope was alive.

“Caribou!” I gasped.

Steve was already counting. “A few hundred,” he guessed, but the retreating fog revealed more animals with each passing second. “Times fifty,” he corrected half a minute later, but even that ­wasn’t enough to account for what was unfolding before our eyes. It was late June 2001 — just after the summer solstice — and we found ourselves amid a sea of animals coursing northwest. Caribou cows and their newborn calves dotted every hillside, pouring over dark rocky slopes and lingering snowdrifts in waves and streams that spread like shadows toward the Firth River. By the time the wind shouldered us off the roof and back into the cabin an hour later, we had counted close to ten thousand caribou, twenty-­four golden eagles, two foxes, thirteen ravens, a pair of rough-­legged hawks, one peregrine falcon, countless gulls and terns, and eight grizzly bears. Even Steve was awestruck.

Although we’d had a long and difficult day on the river, I found it impossible to sleep for much of that night. There was too much light from the midnight sun, too much energy, too many life-­and-­death struggles unfolding around us, to allow rest. All night long, group after group of grunting cows spurred their hesitant newborns over the canyon rim. Cries of protest drifted up from the river as the young struggled in the first big swim of their life. The current tore orderly strings of caribou into a spreading chaos of calfless mothers and motherless calves, the air filling with bellows and bleats. Separated animals pulled themselves onto the rocks and raced up and down the opposite bank. Lone calves disappeared over the horizon; distressed mothers plunged back into the water, and the eagles and grizzlies patrolled the gravel bars, waiting for the calves that were struggling in the whirlpools to wash up.

We settled for short naps punctuated by long bouts of watching, but no sooner had we bedded down than a cacophony of noises sent us running out the door. A bear had a group of caribou running; a family of foxes yipped from where they watched on the far side of the river; and above all of it, a pair of screeching peregrine falcons took flight.

I called my fiancée, Leanne Allison, on the satellite phone and tried to describe the scene: the grizzly bears, the thousands of caribou, and Steve and I in the middle of it — the only people for hundreds of kilometres. When another group of animals thundered past, I held the phone out toward them, but the distance was too great. She was in the city of Vancouver; I was in the wilds of northern Yukon — and my words and the muffled sounds ­weren’t enough to communicate the power of the migration. And yet there was something in my voice, she later told me, that said the lives we’d committed to living together were about to change.

The seed of the idea to follow the caribou was planted the next morning when the last animals crossed the river, climbed the ridge above us, and disappeared. At least 10,000 cows, calves, and young bulls had passed in the previous forty-­eight hours, and the silence that followed them was almost unbearable. If not for a few despondent cows still searching for their lost calves, I might have thought it had all been a dream. But it ­hadn’t been, for no matter how fleeting the migration was, its energy had passed right through me and in its wake was a space, a loneliness, a yearning where none had existed before. I watched the last bereft cow give up hope and trot off after the others. Where were they going, I wondered. Where had they come from? And what other obstacles lay ahead?

But the river pulled me north toward the coast, not west along the foothills. The answers would have to wait.