KEMPTON, Pa. - Every autumn they came to Hawk Mountain, the men carrying shotguns, rifles, ammunition, and whiskey, the women toting picnic baskets and children. From a rocky vantage point, the sharpshooters took aim at the migrating birds that, by instinct, came flapping, soaring, and hovering along the narrow ridgetop.

When the hunters fired, there was an enormous shudder of sound followed by the acrid tang of gun smoke. Then six seconds of eerie silence. Finally came the loud crackling as dozens of birds, some of them weighing as much as 14 pounds, crashed into the dry leaves on the valley floor below. Some were already dead, others would die slowly of hunger and thirst. All were left to rot.

The shooters and onlookers cheered and whistled, for they were performing a civic good - ridding the world of the hated hawks that were believed to prey on domestic chickens and small game like rabbits and pheasants. Never mind that very few hawks actually prey on chickens or small game. And too bad that many other species, including bald eagles, were also part of the indiscriminate slaughter.

This week, thousands of devotees, fueled with anticipatory adrenaline, are making the same trek to the same vantage point. Only instead of Remingtons and Winchesters, they are toting Nikons and Canons. And there's a special air of celebration - for it was 75 years ago that the shooting gallery became a sanctuary that ever since has provided safe passage for an average of 20,000 southbound hawks, eagles, falcons, and other birds of prey, or raptors, that are identified and counted yearly.

Every autumn the migrating birds perform incredible feats of navigation, journeying more than 6,000 miles from the Canadian Arctic to southern Chile. In the eastern United States, the birds follow the 300-mile Kittatinny Ridge because it enables them to coast on air currents called thermals or on updrafts of air deflected off the mountain. With these natural assists, they are able to soar and glide with a minimum of effort. At Hawk Mountain this flyway narrows to a bottleneck, funneling the birds past the observation points at eye level.

This spectacle has made the Hawk Mountain Sanctuary in Berks County, 75 miles northwest of Philadelphia, a shrine for dedicated birders, and this fall an estimated 60,000 experts and novices will visit the sanctuary, several thousand of them on Columbus Day weekend.

"The slaughter went on for most of the early 1900s," says Lee Schisler, president of the sanctuary. "The shooting was so heavy on Sundays that local scrap dealers came up the next day to recover all the spent brass shell casings. To this day, hikers still occasionally find shells."

"Historically," he adds, "raptors have had a bad image in the public mind. The bald eagle may be our national symbol, but there used to be a bounty on them. It took a long time for that attitude to change."

The person responsible for that change was a New York socialite named Rosalie Edge, a little-known but hugely important figure in the American environmental movement. Edge was appalled by photographs of the shootings and raised enough money to first lease and then buy a 1,400-acre section of the mountain that included the best vantage points. Then she posted a guard in 1934 and told the hunters to go away. Today, the sanctuary has expanded to 2,600 acres and is owned and operated by a nonprofit association with more than 9,000 members and an annual budget of $1.8 million.

On a recent day, the parking lot atop Hawk Mountain was filled with vehicles licensed in New York, New Jersey, Delaware, Maryland, Virginia, Mississippi, Illinois, and Ontario. Most of the visitors had climbed to the North Lookout, a forested limestone outcrop that affords a 180-degree, 50-mile view of Kittatinny Ridge; the bluish humps of the Appalachians stretch in both directions as far as the eye can see. In the valley, farm fields run to the horizon, dotted with barns and houses, ribbons of smoke curling from their chimneys.

The view alone is enough to justify the journey, but most of these people have much more in mind. They sit on rocks with binoculars raised to their eyes and speak in hushed, reverential tones. "Two broadwings on the left." Binoculars arc in unison. "There's another!" Between sightings, apples and granola bars are munched. "It's a red-tail female probably." There are hurried jottings in notebooks. "Three kestrels - no, four!" An osprey comes in high, and the binoculars rise. "No bald eagles yet, but we saw three last week."

Some of the watchers hold counters with a dozen or more buttons, each color-coded for a particular species. Observers have been counting raptors at Hawk Mountain since it was closed to hunters in 1934. The information is critical not only in assessing the health of bird populations but also in evaluating a broad range of environmental change. Rachel Carson used Hawk Mountain data as one of her sources to link the use of DDT to declining bird populations in her classic Silent Spring.

Indeed, a new biography contends that it was Edge, rather than Carson, who was the nation's first environmental activist. "Edge, more than any other person, is the one who slowly and relentlessly transformed America's ailing and ineffective conservation movement into an activist and inclusive environmental movement that led up to the publication of Rachel Carson's seminal Silent Spring in 1962," says Dyana Furmansky, author of Rosalie Edge, Hawk of Mercy.

"Rosalie Edge believed that individual political activism coupled with education are environmentalism's key tools, and she incorporated these principles in her life's work by creating the world's first sanctuary for birds of prey," says Furmansky. "She also led the campaign to establish two national parks and expansions of existing parks for reasons of habitat and species preservation. She was the continuous public voice against the use of pesticides beginning 30 years before Silent Spring was published. And she was a profound influence on the men who established the Wilderness Society, the Nature Conservancy, and the Environmental Defense Fund."

Furmansky admits that thus far she is a "minority of one" in her assessment. But to the assembled here this week, there is no doubt that it was Edge, more than any other person, who silenced the guns of Hawk Mountain 75 years ago and granted safe passage to the raptors that have migrated for centuries along the stony spine of the Kittatinny Ridge.