For the next few weeks, Bozeman's Fish Technology Center will focus on goat technology.

On Monday, more than 400 Boer goats were released from a semi-trailer to wreak havoc on the weeds that have started to dominate Drinking Horse Mountain at the mouth of Bridger Canyon.

For two weeks, the public land around the U.S. Fish and Wildlife Service Fish Technology Center will be closed to the public as yearling goats scour the area of invasive plants that are crowding out native species.

Then, for the next few years, the goats will return to ensure that the weeds aren't given the chance to rebound.

BFTC Friends Group spokeswoman Cyndi Crayton said that for a few years, she'd donated bugs that specialize in attacking various invasive plants as a form of bio-control. But for the bugs to be more effective, the goats needed to clear away the brush so the soil would warm and the bugs could get down to the plant roots.

“Goats are like giant bio-controls,” Crayton said. “But just like bugs, goats can't do the job in a year. It takes three or four years to knock the weeds down.”

To avoid using herbicides in such a popular area, Fish Technology Center director Bob Muth said he tried to get some goats to graze the area last year, but the effort stalled.

Then this winter, Muth got a call from Laura Soderquist, who offered the services of Idaho-based Prescriptive Livestock Services, which sends goats throughout the West to combat weeds.

The goats that arrived Monday were grazing weeds near San Diego last week. When they're done here, they'll head for Red Lodge.

Soderquist, a graduate student at Montana State University, oversees the company's Montana operations, working closely with Peruvian herder Alex Gallardo Ricoldi to steer the goats to areas with problem patches of weeds.

On Drinking Horse Mountain, those weeds include leafy spurge, Scottish thistle and knapweed with a little bit of hemlock and mullen.

Goats can kill leafy spurge by eating all the leaves. Unable to photosynthesize its food, the spurge plant will use up its remaining energy reserves trying to grow leaves the next year – which the goats will eat again, finally killing the plant.

Another advantage of goats, as compared to sheep, is that seeds break down in their digestive systems, so the seeds can't germinate when they come out the other end.

“Goats are awesome because they eat all the weeds first. Once they've gone through the weeds, we move them on to the next spot,” Soderquist said.

Tuesday morning, the goats had already devoured the weeds at the base of Drinking Horse Mountain trail.

“We'll be taking them up the mountain today. There's spurge along the way, but there's a pretty good patch of spurge up in the saddle at the top,” Soderquist said.

Ricoldi whistles commands to his herding dogs to keep the herd moving together, but it doesn't take much.

“None of the goats want to be alone so they bunch up. The herd moves like a giant amoeba,” Crayton said.

That amoeba action is good for the soil with hundreds of pointy hooves aerating the turf.

Soderquist said they'll spread wildflower seed in some areas and let the goats till them in.

Once the goats are in a target area, Soderquist and Ricoldi sometimes set up as much as a half-mile of portable electric fence to allow the goats to graze peacefully.

Ricoldi also has a large Pyrenees guard dog to ensure that peace isn't broken by predators or other dogs. That's the main reason the area is closed to the public.

“He thinks he's a goat,” Soderquist said. “He'd go after and maybe kill somebody's dog if they went after the goats.”

USFWS scientists will take advantage of the situation, comparing grazed to ungrazed areas over the next five years to evaluate the effectiveness of goat bio-control.

Muth said several organizations came together to make the goat project happen.

The BFTC Friends donated $8,000 this year, collected through donations, facilities rent and fish food vending machines.

Muth said federal aquatic invasive species grants would help in future years.

The Gallatin Valley Land Trust is donating volunteers and services, while the Montana Outdoor Science School, located in the Fish Technology Center, is handling the project account.

Executive director Steve Eshbaugh said he's managing the books for free due to the importance of the project.

“Leafy spurge started moving in in the early ‘80s, and it's only gotten worse, just like aquatic invasive species,” Eshbaugh said. “Most people who hike here agree that the weeds are bad, so few have complained about the trail closing.”

Some people are even asking how to get goats to weed their properties, Muth said.

“People have really latched onto this. When we tweeted that the goats were here yesterday, it got more than 268,000 media hits and was the most repeated government tweet of the day,” Muth said.