美国国家公共电台 NPR The Bountiful Benefits Of Bringing Back The Beavers（在线收听）

SUSAN DAVIS, HOST:

Few species transform their surroundings enough to make big, ecological changes. Humans are one of them. Beavers are another. And once upon a time, hundreds of millions of beavers used to populate North America - not anymore. And their loss has caused immeasurable damage to mountain ecosystems. As Luke Runyon from KUNC reports, efforts are underway to bring the beaver back.

(SOUNDBITE OF WATER CRASHING)

LUKE RUNYON, BYLINE: It's early in the morning. And Juli Scamardo and I are wearing grayish-green chest waders, trudging through the mud to find a beaver meadow inside Rocky Mountain National Park.

JULI SCAMARDO: These are like mazes. It's hard to get through a meadow and know where you're going.

RUNYON: Scamardo is a master's student at Colorado State University. She's studying how beavers alter landscapes.

SCAMARDO: They definitely are engineers. And they change their environment to suit them. And it also happens to suit a lot of other species...

RUNYON: ...Like birds, fish and insects. And scientists have shown that we get lots of benefits, too. Beaver dams improve water quality, trap and store carbon and replenish groundwater. That's why reintroduction projects are underway in states like Nevada, Utah and Wyoming. And the idea is popping up in some unexpected places.

SCOTT HELKER: Hi. My name's Scott Helker. I'm running for governor.

RUNYON: Beaver reintroduction is one of the main planks of Helker's entire campaign. He's running as a libertarian in Colorado.

HELKER: Honestly, the first time I introduced this, I had one minute. Trying to explain the importance of beavers in a minute is impossible.

RUNYON: Like how a dammed stream could provide a cascade of beaver ponds with water infiltrating into the ground.

HELKER: It's one part of many solutions. But it's a cheap solution. It's easy to do. And it'll fill up the aquifers. And that's what we want to accomplish, I think.

RUNYON: Bringing beavers back into areas that haven't seen them in a long time has been done before. Not long after World War II, the Idaho Department of Fish and Game relocated beavers throughout the state.

(SOUNDBITE OF PROMOTIONAL FILM)

UNIDENTIFIED PERSON: In preparing for the operation, beaver must be sorted for even size and weight.

RUNYON: In this promotional film, game wardens load beavers into wooden crates with parachutes attached. Yes, at one point, we dropped beavers into the back country from airplanes.

(SOUNDBITE OF PROMOTIONAL FILM)

UNIDENTIFIED PERSON: Now into the air and down they swing, down to the ground near a stream or a lake.

RUNYON: Reintroduction efforts today are more targeted and have a varied track record of success. In his new book, "Eager: The Surprising Secret Life Of Beavers," science writer Ben Goldfarb says a state like Utah only has about 10 percent as many beavers it could actually support given the available habitat.

BEN GOLDFARB: And I think that's probably pretty typical, that we're at a very small fraction of the potential beaver abundance.

RUNYON: Back in Rocky Mountain National Park, Julie Scamardo says sections of the park and vast swaths of the American West seem primed for a beaver comeback. But they're not showing up.

SCAMARDO: So we're still kind of asking the question of, like, what else do you want? And having a beaver psychologist would really be the best for these projects, but we don't have any of those so...

RUNYON: We might not know their innermost thoughts. But that's not stopping researchers like Scamardo from trying to boost beaver populations. And while they don't have any set plans for reintroduction at this park, officials have considered bringing beavers in to help regrow vegetation along streams, though they probably won't drop them from airplanes. For NPR News, I'm Luke Runyon in Fort Collins, Colo.