Shortly after sunrise on a morning in mid-June, I stood with a group of people on a little hill in Lamar Valley in Yellowstone National Park. We looked down on the winding Lamar River, and across it to the broad alluvial plain where small bunches of bison and pronghorn antelope grazed. Some of us searched the valley with binoculars, or adjusted the half-dozen spotting scopes that stood on tripods nearby, aimed at the morning's main attraction: a sow grizzly bear and her twin cubs, feeding on the remnants of an elk carcass.

A hundred yards or so beyond the bears, a bull bison rubbed his ponderous head against a fallen cottonwood log. Seated a respectful distance from the bears were six wolves. Ravens and magpies fluttered and stalked around them.

To see wolves and grizzlies together is not that common in Yellowstone, so there was a hushed excitement in our little group. We watched the scene for more than two hours, taking turns looking through the scopes, until at last the sow strode away, her great silver shoulders rolling, her long steps eating up the ground toward the distant timber, the cubs scrambling behind her.

The wolves moved in, gnawed the white ribs for a while, rolled and played a little, then rose and trotted off, past the unconcerned bison and antelope. A coyote appeared out of nowhere and moved in cautiously to grab what he could before the ravens and magpies demolished it.

This was the high point of our weekend trip. A close second was the opportunity to see Yellowstone's famous bison and observe their grazing behavior. Bison don't seem to graze heavily on the edges of ponds and wetlands. The small streams meandering through Yellowstone's wet meadows are bordered by undisturbed sedges and rushes; the bison graze away from the water, while cattle would have been right down on the stream banks. As long ago as the early 19th century, Hudson Bay Company diarists were writing what modern bison ranchers confirm: that the animals don't linger in riparian areas if given a choice. But there's nothing like witnessing something for yourself. It was one more confirmation to me that bison belong in the West's mountains and plains, and cattle don't.

It's not the fault of the cows. They are what their evolutionary history in the humid woodlands of Europe has made them. They are browsers as well as grazers, creatures who once boasted formidable horns and could back into a thicket to protect their calves against predators. Even in the New World, they ran wild and multiplied in the mild climate of eastern Texas. They never asked to be turned into polled meat factories and abandoned on the range to the mercies of harsh winters, cancer eye, larkspur poisoning and snakebite.

In all the states surrounding Yellowstone, for instance, cattle simply cannot survive - on or off public land - without extensive human assistance. This assistance continues to exact a fearful price on the area's land and water.

But things are changing, on several fronts. Eating breakfast later that morning at Mammoth Hot Springs, I read two pieces of news tucked into the business section of the Billings Gazette. One was the second earnings warning by McDonald's in two quarters. A slowing economy and the mad cow disease fiasco in Europe are eating into its profits. The other was that Tyson Foods, the world's biggest poultry producer, has been told by a Delaware judge that it can't back out of its offer to buy IBP, the giant beef packing corporation, after all. (Tyson got cold feet after learning that IBP had exaggerated its net worth.)

I doubt that these two events are good news for cattle prices. The economics of "traditional" ranching are about to converge with a growing public awareness of the ecological damage inflicted on the West by cattle. When the two meet - and I am confident that they will - the West's native ungulates will be there, waiting in the wings.