For decades there were no wild wolves left in Yellowstone. But they're back—seventeen fierce, formidable packs of them. Joe Kane takes a howl-i-day

The howl of a lone wolf known as The Intruder blasted out of Hellroaring Canyon one gray winter morning like the most evocative notes of the best blues singer I'd ever heard. Nine of us had been standing in the snow for half an hour, up along the northern boundary of Yellowstone National Park, sipping thermos coffee and stamping our feet against the toe-numbing cold. We'd glassed a coyote and two bald eagles tearing flesh off an elk carcass a quarter mile west, across the canyon. Suddenly, the coyote pricked up its ears and bolted, and the eagles streaked away like jets, while from our left, hidden down in the trees along the creek, rose three low and rumbling notes: the call of a female wolf. She belonged to the Druid pack, which The Intruder had been shadowing for a month, trying to lure her away. The pack's alpha male kept chasing him off, but he wouldn't quit. It was pure rock and roll.

The landscape went dead silent. Beyond Hellroaring Canyon, I could see the massive flanks of the Absarokas soaring above snow-blanketed valleys and ridges clotted with sagebrush and conifer. We were within earshot of elk, bison, coyotes, bears, antelope, deer, and foxes by the hundreds. But there is no sound in the wilderness like the call of the wolf, no sound that so demands: Listen up.

A few seconds later, The Intruder responded with two long, low notes, then shot up an octave and held a note for maybe five seconds. And then, I swear, he bent that note the way a blues player would, to make it wail. At once plaintive and defiant, filled with love, need, bravado, and fear, his song arced across some of the most spectacular wildlands in America. Then he added three low notes that lent grace and charm to his performance. In all, he sang for about fifteen seconds, but time seemed suspended. No one spoke. Every face was turned up-canyon, toward that voice. I noticed that I was holding my breath.

Then The Intruder really got down. For the next ten minutes, he sang his young heart out. My wolf's a little rough, but the gist was: Your old man don't scare me. I'll stand here and howl till dawn if I have to. He can't keep us apart.

Down in Hellroaring Canyon, the she-wolf weighed her options: life with the folks, structured but secure, or a leap into the void with a boy who could sing like the devil.

The National Park Service killed the last wild Yellowstone wolf in 1926, and for the next seventy years, wolves were the missing piece in the Yellowstone mosaic, the one element that marred its claim to being the largest "intact" ecosystem in the continental United States. But in 1995, the U.S. Fish and Wildlife Service imported fourteen gray wolves from Canada; it released seventeen more in 1996. Since then, the wolf has reestablished itself far more successfully than anyone expected. It's now considered Yellowstone's dominant predator, more voracious and peripatetic than even the grizzly or the mountain lion. Seventeen packs, numbering about 220 wolves, roam what's known as the Greater Yellowstone Ecosystem, which comprises two national parks and six national forests and straddles the states of Montana, Idaho, and Wyoming.