Enlarge Navarro Vineyards Panama sheep graze near grapevines at the Navarro Vineyards in Mendocino County, Calif., to help control growth.

Sarah Cahn Bennett, co-owner of the family-owned Navarro Vineyards in Philo, Calif., says they began using the flock of 70 in June to keep the vineyard trimmed and minimize the work of tractors and manual labor.

Grazing vineyards is just one application of a growing niche industry that is harnessing the eating power of animals to control invasive weeds, maintain lawns and clear fire-prone grasses. The animals are an alternative to using machinery that burns up fossil fuels or herbicides that, in some cases, can seep into groundwater.

"It's very widespread, but there's lots of room for more application," says Sandy Tartowski, a New Mexico-based scientist in the research division of the U.S. Department of Agriculture.

Called conservation or targeted grazing, the use is more predominant in the western U.S., she says, but livestock have cleared the brush around power lines in Durham, N.H., and have been used to eat up the invasive vine kudzu in Chattanooga, Tenn.

Homeowners in California have rented out goats and sheep to gobble up vegetation near their properties that, in dry conditions, can catch fire, says Terence McHale, policy director the California Department of Forestry and Fire Protection Firefighters.

"Goats, one of the great things is not only are they cheap, they'll eat anything," he says.

Charlotte Lewis, co-owner of Living Systems Land Management in San Francisco, helps direct a herd of more than 2,200 animals to a clientele that includes homeowner's associations, local governments and businesses.

She says that sites with hillier terrain, limited access to water, and the need for more fencing will drive up the price tag. When her company does a job, a shepherd lives in a trailer on site. "We have more projects than we can do right now," Lewis says.

Elsewhere:

•Carroll County, Md. This summer the Maryland State Highway Administration is renting a herd of goats and sheep to control invasive weeds in a wetland area. Spokesman Charlie Gischlar says using a 7,500-pound lawn mower in the area would embed ruts that could destroy the area's hydrology and endanger the habitat of the Bog Turtle, a 4-inch turtle that is listed as a threatened species.

"I do not doubt that we might do this on other sites in the future," says Bill Branch, a highway administration environmental analyst.

•San Jose. The city is enlisting goats and sheep to graze more than 600 acres this year, up from when the city had 4 acres grazed in 2007, says Matthew Weber, an environmental services specialist for San Jose. The annual $75,000 cost is about 45% more than using mowers and herbicides, but Weber says it's impossible to put a price tag on the ecological benefits.

"It's ironic that in the heart of Silicon Valley, we're reverting back to rather low-tech, traditional land management," Weber says.

•Mountain View, Calif. In May, outside of the Google headquarters, a herd of about 200 goats cleared out a field of weeds and brush to reduce the area's fire hazard, says Niki Fenwick, a spokeswoman for the company. The cost was about the same as mowing, she says.

Transportation departments at least five states — Delaware, Maryland, New Jersey, New Mexico and Oregon — have used grazing animals to minimize roadside vegetation, says Doug Hecox, a spokesman for the Federal Highway Administration.

Selecting the right animal for the job is becoming a refined process, says Karen Launchbaugh, an associate professor at the University of Idaho's department of rangeland ecology and management.

"Goats are especially popular for shrubs and trees. Sheep are better for herbaceous (leafy) weeds. And cows and horses if you have dense grasses," Launchbaugh says.

Latshaw reports for The Daily Times in Salisbury, Md.