(Photo: Derek Davis/Getty Images)

Forget Pesticides—Send In the Goats to Save America’s Marshes

Researchers find that grazing livestock keep an invasive plant from destroying coastal wetlands.
Sep 30, 2014· 2 MIN READ
Richard Conniff is the author of House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth and other books.

As I write this, I am sitting on my porch in Connecticut looking out at a coastal salt marsh, a habitat that seems to be increasingly under threat everywhere, in part because of a tall grass called Phragmites australis. When I first moved here, the marsh was a wall of phragmites, a dense stand 10 feet high from one side to the other. Hardly any wildlife seemed to live there except red-winged blackbirds. The roots, or rhizomes, of the phragmites grew one on top of the other, crowding out native plants and threatening to turn the marsh into dry land.

When a study demonstrated that out-of-control phragmites are an invasive variety introduced in the 19th century from Europe, I went to work, deploying a one-man version of the anti-phragmites protocol now used by many state environmental protection agencies. Wearing a backpack sprayer, I cut tunnels through the dense foliage, then worked my way back out, spraying an herbicide called Rodeo, an aquatic variety of Roundup, on the leaves of the phragmites. I wasn’t comfortable with the idea (and in neighboring New York the practice is illegal). But it seemed to work. The phragmites started to die back, and I saw a lot more wildlife, from otters to glossy ibis.

Now though, a new study proposes a better way get the same results with less work, lower cost, and fewer environmental complications: Send in the goats.

Duke University ecologist Brian Silliman got the idea while doing research on marshes in Europe. He noticed that the same variety of phragmites turned up there mainly in drainage ditches and at construction sites. But the marshes remained open. Livestock commonly graze in the marshes, a practice that would horrify most American conservationists. But Silliman wondered if the livestock were keeping the phragmites in check.

It turned out that horses, cows, and goats all readily eat phragmites, and when Silliman got back to North Carolina, he discovered that Andrew H. Baldwin at the University of Maryland had already begun a series of experiments. The researchers set up 40-meter-long fenced enclosures in a Maryland marsh that looked the way mine used to look: wall-to-wall phragmites. Then they added in two goats, on the theory that one would be lonely and three would eat too much too fast.

After a few weeks, the goats had nibbled the phragmites down to stubble, and the researchers moved them to the next enclosure. When the phragmites resprouted, the goats came back for a second round. The idea, said Silliman, was to burn up all the energy reserves stored away in the dense tangle of roots. By the end of the experiment, the goats had reduced the phragmite cover from 94 percent of the test area to 21 percent. Native plants increased proportionately.

But is the idea practical on the kind of large scale needed to save coastal marshes? The researchers point out that land managers “have treated more than 80,000 hectares of marsh with herbicide over the past five years with limited success, despite costs that exceed $4.6 million per year.” Mechanical techniques, including digging up or mowing the phragmites, are ineffective and more costly.

The goat idea isn’t an entirely risk-free alternative. The new study warns that the use of goats would have to be timed to account for nesting birds and other environmental considerations. It would also require setting up temporary enclosures with electric fencing, said Silliman, to keep the goats from devouring native species. But he argued that it would be a lot cheaper to pay farmers a fee to graze their goats in the phragmites than to pay contractors to spray herbicides.

I told Silliman I didn’t think state environmental agencies would go for it. But he pointed out that a town in North Carolina is already using goats to control kudzu, and the New York State Department of Environmental Conservation is testing goats for control of invasive species on Long Island.

Will others follow? Stay tuned. With luck, we may yet see our coastal salt marshes reopened and celebrate with a feast of locally grown Jamaican curried goat.