BOZEMAN, Mont. -

More than 400 goats are helping get rid of noxious weeds on a popular north Bozeman trail.

Invasive noxious weeds are a problem throughout the state of Montana.

The Department of Agriculture says there are more than 32 noxious weed species in the state, and about 7.6 million acres have been infested.

The Department of Agriculture says they award around $2.5 million a year in grants to counties, and education and research groups to combat weeds.

State weed experts say fighting invasive weeds is necessary to keep a healthy and diverse native plant population.

"Most of the noxious weeds will be able to out-compete, out-grow our native plants," explained Dave Burch, the State Noxious Weed Coordinator for the Department of Agriculture. "So basically what that does is create a monoculture of a weed problem, and without any natives being there the monoculture just reduces our native plants."

Goats are grazing off Bridger Canyon Road at the Fish Technology Center and the Drinking Horse Trail.

Land managers have many tools to help fight weeds -- from chemicals to insects that specifically target noxious weeds.

400 goats, four herding dogs, and a Peruvian goat herder named Alex, are all working together to get rid of noxious weeds in Bozeman.

"We're kind of using nature to combat nature's problems," explained Lora Soderquist, the regional manager at Prescriptive Livestock Services.

Soderquist's team was hired by the Bozeman Fish Technology Center and the Montana Outdoor Science School to tackle the leafy spurge growing on the Drinking Horse Trail.

"This is a very low-impact, natural way to get rid of noxious weeds without spraying," explained Steve Eshbaugh, the executive director of the Montana Outdoor Science School.

The herder and herding dogs keep the goats confined to the infested area, and the goats go to work, eating the leaves, stems, flowers and stalks of the weeds. The goats are a perfect animal for the job because, unlike wildlife that eats the grass, the goats actually prefer eating the noxious weeds.

"The wildlife doesn't eat the leafy spurge, they don't eat the noxious weeds, it has -- by human terms and by wildlife terms -- it has no value either," Eshbaugh said.

According to North Dakota State University Extension Service, goat and sheep grazing will not completely eliminate leafy spurge, but it will slow the spread and make room for native grasses.

The Montana State Noxious Weed Coordinator explained grazing must be done before the plants produce seeds to prevent further spread.

Soderquist explained the goats' benefit goes beyond just eliminating the noxious weeds.

"They help invigorate the soil with all their little hooves," she said.

Soderquist and Eshbaugh explained land managers are moving away from using chemicals.

"We need to expand our toolbox and have more integrated approaches," Soderquist said.

She explained using goats is an effective alternative.

Drinking Horse Trail will be closed while the goats do their work, for about two weeks.

In Missoula, they are using sheep to graze on noxious weeds in the hills north of town, but in the past week, three sheep were attacked by dogs.

Missoula officials are planning extra patrols to make sure people are following the rules.