This is the time of year ranchers across the Northern Hemisphere move sheep by the tens of thousands from the mountains to lowland pastures. In the U.S. Rocky Mountain states, sheep drives can cross 200 kilometers by foot. But land that used to be open range is gradually turning into subdivisions, golf courses and busy streets. In one central Idaho valley, ranchers have a colorful way to win newcomers over to sharing the land. As correspondent Tom Banse reports, they parade their sheep right through the center of swanky Ketchum-Sun Valley.

Brothers Mike and Mark Henslee are walking with about one thousand sheep. They started high in the Stanley Basin of central Idaho and plan to wind their way about 250 kilometers south to warmer pastures near the Snake River. Along the way, they have to somehow move all those sheep through fashionable Sun Valley, the getaway of movie stars, politicians and millionaires.

"Bruce Willis has that house down by Hailey which we go past tomorrow," Mark notes, and Mike chimes in, "The Kennedy house is up here somewhere that we probably go past... or the Kerry's. We go past a lot of 'em."

The flock stays on steep hillsides to skirt the celebrity estates. But it goes right down the first fairway of the Bigwood golf course, and Mike observes that the sheep not only grazed the course, they fertilized it. Fortunately, it's too cold for golf this morning.

Just a few decades ago, domestic sheep outnumbered people in the Rocky Mountain West. Today, people far outnumber the sheep - not just here in Sun Valley, but all around the region. In some cases, the century-old tradition of the western sheep drive is being replaced by more expensive trucking.

It hit home for sheep ranchers John and Diane Peavey in the mid-1990s, when Sun Valley's communities built a bike path in the livestock right-of-way.

"It was one call after another," Diane recalls. "'Get your sheep off our bike path. Their droppings are getting caught in our Rollerblades and our bike wheels.' John and I, we kind of looked at each other, sighed and went, 'Now what?'"

Peavey and her husband run one of the oldest sheep ranches in this part of Idaho. They decided to become proactive, to share their heritage with the recreationists, the vacation home owners and other new arrivals. Now every fall, one of the local sheep ranching families trails their flock right through the center of the resort town. It's turned into an annual festival called the Trailing of the Sheep.

"That was not a re-enactment," Peavey stresses. "These sheep would be moving from the mountains to the desert country regardless of this festival."

The three-day festival includes concerts, storytelling, sheep dog competitions and demonstrations of sheep shearing. But the highlight is the parade, as old sheep wagons, bagpipers and Basque dancers lead hundreds of sheep down Main Street.

Sun Valley attorney Jim Phillips has acted as a go-between for developers and wool growers. He says the law is on the ranchers' side when swank developments and mansion sprawl threaten to block the sheep migration.

"[But] you can't just show up [at] a development and say, 'Hey, we want a trail across your property,'" he says. "It has to be, 'We've had this trail. This trail has been used as long as anyone can remember.'"

Phillips says ranchers have to insist that developers recognize that history and provide for its continuation. He adds that they could make a stink about maintaining their trail rights, but they want to get along and sometimes accept minor detours.

Rancher Diane Peavey says the Trailing of the Sheep Festival deserves some of the credit for the recent improved coexistence.

"Suddenly, where there had been animosity ? just by reaching out and sharing stories, sharing music, dance, food, sharing the sheep, sharing them with communities that don't know anything about sheep ? they come to understand and wait each year," she says. "'When are they coming? We can't wait for the sheep. Can we help?'"

As a river of sheep flows across the road outside town, Linda Mueliger waits in her car, unperturbed by the wooly jam.

"It's great," she says. "The sheep, it's a wonderful thing for the community. It's lots of fun, yeah."

Last year, the Trailing of the Sheep was listed by the vacation Web site MSN Travel as one of the top 10 fall festivals in the world.