SILVER CITY, Idaho - Imagine a silver-haired 52-year-old fellow walking into a saloon in this remote mountain town in the 1920s.

He slams open the saloon's swinging doors and says, "All right, who owns those cows sprawled in the middle of Jordan Creek? Jordan Creek is full of crap and I want those cows out! Now!'

Imagine the response. A couple of cowboys at a corner table would slowly rise out of their chairs, rub the bone-chiseled grips of their six-shooters and stare at the man named Jon Marvel. "Let's settle this outside," they'd say.

Maybe they'd soak him in a water trough. If he were lucky.

But it's 1999, not the 1920s. And Jonathan Marvel, a successful architect from Hailey, Idaho, is not afraid to attack what he calls the West's sacred cows.

He has proudly worn a button that urges "End welfare ranching," and he targets ranchers who use federal land as well as Idaho state land, along with both the Bureau of Land Management and the U.S. Forest Service - in Idaho, Oregon, Nevada, Utah and Wyoming. More than a few ranchers probably wish they could settle things the old-fashioned way.

"He's an arrogant, ignorant asshole," says Jay Cox, an Owyhee County, Idaho, rancher.

"Out here in Castle Creek, the BLM is cutting cattle numbers and they're trying to fence every mile of the stream. They cut me back to the point where I'm losing $28,000 a year. And Marvel ... he just smiles and laughs," Cox says.

Even some of Marvel's friends marvel at the chutzpah of this anti-grazing activist who has found new ways to attack the state and federal permits that public-land ranchers say they need to survive.

One friend, who requested anonymity, called him "Slobodan Marvel," playing off the name of the Serbian murderer and ethnic-cleanser, Slobodan Milosevic. "He's easy to hate," he adds, "but you have to admire his guts and sense of humor."

The agriculture weekly Capital Press, based in Salem, Ore., interviewed Marvel on June 18, and concluded that while he was "more up-front than usual," he was also "immune to reason."

Its editorial concluded: "We have the impression that he harbors a rage against public-lands grazing, and any amount of reasoning, analyses or demonstration projects are unlikely to make a difference with him."

A slow, deliberate talker, Marvel says his aim is to stop the environmental damage caused by livestock on public lands, focusing on critical fish and wildlife habitat along rivers and streams. Hence the name of the nonprofit group he began six years ago - Idaho Watersheds Project.

His solution: "Destabilize" the livestock industry to the point where ranchers get so mad and miserable that they quit the business.

"We're creating biological deserts in areas that should be exuberant with life," Marvel says. "If the land could talk, it'd be crying."

Marvel takes a no-compromise position because ranchers, in his view, refuse to improve stewardship, and state and federal politics are rigged in their favor.

"I'm painted as an extremist radical who's trying to undermine their way of life, and some of them call me a communist," he says. "Well, the great irony, of course, is that the system of public-lands ranching is a communist system. It's a command-and-control system. Outsiders cannot participate. There's no democracy. There's no free market. There's no competition allowed. They're in charge."

Criticism of cattle, of course, is nothing new. For the last decade, federal government studies have documented the damage cattle do to arid public lands, endangered fish and streams and rivers.

Marvel is making a bigger splash than previous crusades, such as "Cattle Free by "93," because he's discovered highly effective ways to attack ranchers. His arsenal runs the gamut and includes bidding on state grazing leases, suing state and federal agencies, filing endangered species petitions, appealing grazing plans and mounting anti-cow cartoons on highway billboards.

He gets headlines by attacking wealthy and well-known public-land permittees, such as the Hewlett Packard-leased San Felipe Allotment near Mackay, Idaho, and billionaire potato king J.R. Simplot's extensive grazing leases in southern Idaho.

Marvel mocks federal grazing fees - $1.35 per cow-calf pair per month in 1999 - by comparing them to the cost of feeding a pet hamster. That, he estimates, is $3 per month, while feeding a pet tarantula a month's supply of crickets costs $4.75.