Weird science.

The Mapimi Biosphere Reserve is a loosely defined 425,000-acre expanse of land in the center of Mexico's Chihuahua Desert. It's home to at least 300 vascular plants, 30 types of cacti and 249 vertebrate species, including mountain lions, bobcats and weasels. Much to the chagrin of Reserve scientists, however, it's also a destination for hundreds of tourists with no interest at all in the natural environment.

The "silencios," as the locals call them, favor the supernatural. As they see it, the Mapimi is "The Zone of Silence," where magnetic waves are mysteriously altered or silenced. The silencios believe the zone experiences bizarre biological mutations, UFO landings and extraterrestrial communication.

Environmentalists and Reserve researchers would love to dismiss the silencios as lunatic fringers, but Mapimi has been mythologized into a phenomenon not unlike the Bermuda Triangle. Its popularity continually interferes with the Reserve's scientific objectives and conservationist mission.

The visitors steal plants, rocks and tortoises, trample the landscape and search for non-existent hotels and restaurants. According to Andrea Kaus, an anthropologist and one-time manager of the Reserve, the silencios "represent a substantial population of strangers who wish to see, experience and take away with them a memento of what they perceive to be the strange essence of the Mapimi desert."

The phenomena that foster the Reserve mystique are, Kaus says, baseless illusions. "No one I know of has had any trouble with their radios or compasses in the Reserve," she says. Wild assertions of biological mutation turn out to be routine natural changes. Parts of the nopal coyotillo cactus, for example, become violet during especially dry periods, but the silencios see this as a supernatural wonder. The strange lights that flicker on the horizon--a common desert phenomenon not unlike the Marfa lights in West Texas--are summed up by one local resident as "but they're nothing."

Local residents have reacted with ambivalence, with some exploiting the silencios by selling them maps, guides and refreshments; others, especially ranchers, would prefer the silencios to disappear. The local battle, though, will surely take a back seat to the larger war of public perception. "It seems," says Kaus, "that nearly every cabdriver in Mexico has heard of La Zona del Silencio, but not the Mapimi Biosphere Reserve." CONTACT: Earthwatch Institute, www.wildworld.org/ mapimi.