It's a brilliant Sunday morning in southeast Utah, and a hag mask hangs on the fence before me. Gray hair askew, she gapes at red cliffs through dripping fake blood. The vandal who mounted the mask has also locked the gate to our campsite. No one can get in or out -- a dangerous prospect, since most of the 50 or so folks here are senior citizens.

I'm about to photograph the scene, documenting what to me seems a gruesome tableau, when a voice pipes up: "She's kind of pretty, actually."

"Yeah, she looks wise," adds another.

"Like us!"

"Will you take my picture with her?"

Rose Chilcoat, the rosy-cheeked, energetic 54-year-old associate director of the Great Old Broads for Wilderness, mugs next to the mask as I snap away.

I'm startled by the Broads' calm response to this outrageous threat. The mask comes with an ominous note: "Get out of San Juan County. This is your last warning." But Chilcoat, whose group educates elders about public-lands issues in hopes of making them active stewards, seems unfazed.

Later on, in a more serious moment, she muses: "I never thought little old ladies in tennis shoes would be seen as such a threat." But such extreme reactions to their activism have only encouraged Chilcoat and the Broads to hold fast to what might be called an essential tenet of "Broad-ness": Humor is more powerful than fear.

In a roundabout way, Sen. Orrin Hatch, R-Utah, inspired the creation of the Broads in 1989. New Mexican Susan Tixier and some of her backpacking buddies in their 50s heard how Hatch had argued against wilderness designation, saying that prohibiting motorized access excludes the elderly from the backcountry. "We thought, 'Jeez, we are all old and we still hike!' " recalls Tixier. "So, what better than to have old people, particularly old women, stand up for wilderness?"

"We didn't really want to be 'ladies,' and 'women' seemed like kind of a weak noun," she adds, so Great Old Broads it became. The brash name is a selling point to women of a particular type, notes Chilcoat. Broads enjoy joking as they protest; when they picketed against snowmobiles in Yellowstone, one wore a Winnie the Pooh costume with a sign reading, "I can't 'bear' the noise and pollution." "When you get to a certain age, who cares?" she says.

By 2030, there will be about 30 million more senior citizens in the U.S. than there are now. But their growing numbers aren't the only reason to get them interested in public lands, says Chilcoat. Many are retired and have the time to get involved. And, "There's a certain credibility when elders speak, even in this day and age."

The fast-growing advocacy group has about 4,000 members and has opened 22 chapters, known as Broadbands, across the West and in places as far away as Florida. And while the group is unabashedly pro-wilderness, each Broadband has considerable latitude to choose what it works on. As former executive director Veronica Egan puts it: The Broads are "not anti-anything except poor land management."

Spending time with the group in Colorado and Utah, I met grandmothers who could hold forth in intimate detail on grazing policy and octogenarians who volunteer for the Bureau of Land Management, providing informed critiques of federal land-use plans and studies. How, I wondered, do the Broads transform their members from graying retirees into GPS-wielding, public-comment-making dynamos?