The new kids on the block were at dinner, several hundred of them, chomping, chomping, punctuated by an occasional bleat. The arid hillside in our suburban neighborhood park had been suddenly populated by goats, shaggy white Angoras, deep-chested beige Spaniards, New Zealand Kikos, all methodically munching their way across the rapidly browning landscape. In the process, they were protecting me and my neighbors from that California dry-season nightmare, the blazing, fast-spreading wildland fire.

About 6,000 wildland fires sweep California annually; in the awful 1999 fire season—roughly from April to November—fires consumed 273,000 acres, destroyed 300 homes and other buildings, and caused $500 million worth of damage. The number of fires has quadrupled in 30 years, as population growth relentlessly pushes human habitation ever deeper into fire-vulnerable areas.

When the rains stop in April, vegetation turns crisp and brown; the tiniest spark can set off a major conflagration. Yet there are few weapons against the threat. A prescribed burn, deliberately set to burn the hazardous dry fuel, can too easily get out of hand, as happened at Los Alamos in 2000. "You can't use chemicals," because they leach into the water supply and the areas in danger are far too large, says Mike Phillips, who works in fire prevention for Laguna Beach, where a 1993 fire destroyed more than 400 houses. Fire-prone terrain is often too rugged for mechanized equipment; ferrying in crews by helicopter is far too expensive. "Anyway," says Walt Fujii, former supervisor of parks and trees for Menlo Park, "bring in a hand crew for a day and they're out two weeks with poison oak. And when they cut the stuff down, what do you do with it?"

Send in the goats.

Just who first drafted the genus Capra for environmentally friendly fire safety duty is not clear. But certainly among the pioneers were Brea McGrew, a veterinarian, and her husband, Bob, a fireman, whose four-footed weed eaters have been at it since 1991. During the six-month fire season, the McGrews' hardworking goats can be found lunching in the hills above Oakland and Berkeley, in the coastal slopes behind Monterey and in back of the beachfront mansions in Malibu. Brea McGrew won't even estimate the number of goats in their herd but acknowledges it's in the thousands.

Earlier in the spring, after the winter rains subsided, I drove up to Dixon, a town near Sacramento, to see the goats prepare for their summer job.

"Goats are good for this sort of fuel management because they are primarily browsers," said Brea, explaining that brush, once ignited, acts like a ladder carrying the fire to the treetops. "Goats would rather eat brush than grass," she added. "They like their food right at eye level. At home, the goats ignore the wonderful green grass and look longingly at the scruffy taller stuff beyond the fence."

After the disastrous Oakland Hills fire destroyed more than 2,400 houses in 1991, local governments with vulnerable open space began to seek ways to prevent a recurrence. Fires in the area have been better contained in places where goats have browsed.

Five years ago Walt Fujii began bringing in the McGrews' goats for two weeks at $15,000 per stint to reduce the fire hazard. Not only has the brush been kept under control, but there's been an added benefit. "You wouldn't believe what we took out of there the first year," says Fujii. "One and a half truckloads of junk, bottles, cans, paper—you name it. It was like the snow country after the snow melts. The goats really opened it up."

Now, each April, when the rain stops and temperatures rise, a small caravan sets out from Dixon. Bob McGrew pilots the livestock trailer-truck carrying 450 yearlings and a half dozen mothers with kids. Next comes a small house trailer, to serve as the on-site home for the two goatherds, brothers from the Peruvian uplands, Jose and Ricardo Surichaqui. With them ride two Great Pyrenees guard dogs and two Border collie herding dogs. Brea's pickup follows, carrying water troughs, electric fencing to confine the animals, and food for the men.

With staff from Menlo Park, the McGrews tramp through the terrain, fencing small trees and sensitive native plants to protect them from ravenous appetites. Then the hungry weed eaters themselves arrive. The Surichaqui brothers lead them into a fenced-off area of yellowing wild oats. The goats begin work immediately. Three hundred and fifty of them can denude an acre a day, consuming low branches and foliage, stripping bark from French and Scotch broom and other shrubs, eating grass down to putting-green height. After such a meal, they are moved to another acre.

Brea McGrew stepped back and watched them admiringly. "You know, goats are very intelligent," she said. "They're trainable, like dogs. And they work together. They think. One will get up on her hind legs and pull a branch down for the others, and they'll all browse together."

Throughout California, goats were dining out. Above the championship golf course at Pebble Beach, a herd was systematically carving a 35-acre firebreak. In the East Bay parks, goats were eating their way across 400 acres of buffer area. "What I like about goats," Ed Leong, a park supervisor in the East Bay Regional Park District, told me, "is they do their work so quietly. People who come to our parks don't like the noise of brush-clearing machinery."

Laguna's Mike Phillips said that just three things contribute to wildland fires. "Fuel loads, topography and weather." He paused, then smiled. "We can't change the topography, and we can't do anything about the weather. The only variable to reduce is the fuel load. That's what goats do for us."