very fall, an enormous avian tide
“We call them grinds,” says Doug Thomas, a local farmer. “As far as you can see, thousands and thousands of geese come corkscrewing in. You see these big tornadoes of birds just grinding into the fields.”
Shorebirds including dunlins, dowitchers and least sandpipers also arrive in droves. And through the winter, the entire valley—which stretches from the snow-shrouded flanks of 14,180-foot Mount Shasta to the outskirts of San Francisco—comes alive with a constant cacophony of honks, squawks, chitterings, chirps and purrs. This is the heart of the Pacific Flyway, a major migratory path for millions of birds that travel up and down the west coast of the Americas.
The Sacramento Valley is the northern half of California’s vast Central Valley, which once included some 4 million acres of wetland habitat. But over the past century, the landscape has been retooled for farming and other uses. Today, just 250,000 acres of wetlands remain, largely protected in federal and state wildlife refuges. These remnants still function as vital winter resting grounds and migratory pit stops. The Central Valley provides habitat for nearly two-thirds of the Pacific Flyway’s ducks and geese and one-third of its shorebirds, which pause here to pack on fat before
they head north again to breed each spring.
“That annual cycle,” says Thomas, “all starts here.”
Now, The Nature Conservancy and its partners are working to bolster the flyway with an effort that they
hope will ultimately create a million acres of wetlands here. That’s a daunting goal.
“We’re not going to save the flyway by buying farms one farm at a time,” says Mark Reynolds, lead scientist for the Conservancy’s California migratory birds program. “It’s just too immense of a challenge, and too expensive.”
So the Conservancy is testing a new program, called BirdReturns, that rents habitat rather than buying it. The program pays rice farmers to leave water in their fields for a few extra weeks at critical times during the birds’ winter and spring stopovers in the valley—effectively creating “pop-up,” on-demand wetlands.
“You can do precision conservation,” says Conservancy economist Eric Hallstein, “that lets you pay for exactly what habitat you need, when you need and where you need it.”
Farmers began growing rice here in the early 1900s, and both domestic and global demand has progressively pushed rice production to half a million acres in the Central Valley today. Until the 1990s, growers tended to burn their fields after harvest to rid them of disease and recycle nutrients from the leftover rice straw back into the soil. But as stricter air-quality standards discouraged burning, rice farmers turned to heavy equipment to mash, chop, disk and stomp the straw into their fields—which they then flooded to hasten decomposition.
Although their function as artificial wetlands was unintentional, it turns out that flooded paddies actually make for pretty good bird habitat, serving up a feast of insects and leftover grains. But is it enough to make up for the lost wetlands?
To find out exactly what the flyway migrants need, the Conservancy in 2012 began collaborating with the Cornell Lab of Ornithology. Together with the National Audubon Society, Cornell had developed a crowd-sourced monitoring effort called eBird. The system has aggregated more than 150 million sightings by birders around the world to gain new insight into the migration patterns of individual species.
Cornell used the data to build migration models for 26 species that use the Pacific Flyway. “That allows us to make predictions, week by week, for the timing of arrival of these migrants and their spatial distribution,” says Reynolds.
At about the same time, Reynolds learned that scientists from Point Blue Conservation Science were analyzing
satellite information to determine which areas of the Sacramento Valley farmland were flooded, and when. “They were primarily looking at ways they could predict water availability to do shorebird censuses,” he says. “And I looked at what they were doing and thought, ‘Huh. We could actually use that for conservation.’”
The Conservancy then married the predicted habitat requirements from eBird with the water-availability information from Point Blue. Overlaying the two sets of data brought the habitat gaps into dramatic focus.
“It was kind of like looking at an X-ray and seeing, ‘Oh! There’s a real problem here,’” says Reynolds. “If the illness is chronic habitat deficit syndrome, this was a pretty clear diagnosis.”
Permanently protecting that much land and ensuring it had a reliable supply of water wouldn’t be practical. “We knew that we couldn’t buy our way out of that problem,” says Hallstein. “It was going to take three to five billion dollars.”
The Conservancy has long been known for its deal making to buy properties and establish permanent conservation easements that limit development on private lands. But the standard approach wasn’t going to work in this case, says Sandi Matsumoto, the Conservancy’s director of the migratory birds initiative in California. The birds’ migratory nature, she says, “really changes the conservation problem from place-based protection to something that’s dynamic.”
The team began to think about how they could provide water at exactly those times when the incoming birds needed it. And that, in turn, led to a tightly focused effort to pay farmers to keep water in their fields during a critical four to eight weeks in February and March, primarily to provide shallow water and mud flat habitat for shorebirds.
Amelia Harter farms with her brother outside Colusa, California, in a picturesque spot just north of Sutter Buttes, an ancient volcanic plug that in early February is wreathed in a wizard’s-beard cloud.
“When I saw this program, I thought, ‘This is awesome,’” Harter says. “It not only helps supplement my income, I can also integrate it into a passion of mine, which is helping out wildlife and providing habitat for these birds.”
Last fall, the Conservancy invited Sacramento Valley farmers who were interested to participate in BirdReturns. To spread the word, the organization partnered with the California Rice Commission, which represents the roughly 2,500 rice growers and handlers in the state.
Harter also talked up the program with other rice farmers in the area and helped create the overwhelming response to the test run of BirdReturns. “The idea really caught fire,” says the Conservancy’s Reynolds.
For farmers, there are real trade-offs to participating in the program. “By holding our water, we’re taking a risk,” says Thomas. Doing so increases the odds that fields won’t be dry enough to run necessary equipment in time for planting by late May. “If it rains, then we’re screwed up,” he says. “Everything that goes along with that has to be factored into your economic equation.”
Reynolds and his team are still crunching the numbers from this spring. But they have already found that fields flooded through the Bird Returns program held, on average, 30 times more shorebirds than nonparticipating fields—and as much as 50 times more in late March, when fields have traditionally gone totally dry. The numbers look especially good for dunlin, which breed in the Arctic and are considered an indicator species for migratory shorebirds in general. At one point in March, BirdReturns fields hosted an estimated 20 percent of the entire Central Valley’s peak migratory population of dunlin.
“It’s pretty exciting,” says Reynolds. “With a small pilot program, we were able to provide benefits for a large percentage of all the dunlin in the state. We had some inkling that this might be a good idea, and now we have the data to show the impact.”
Reynolds, Hallstein and Matsumoto hope to gradually ramp up the amount of land enrolled in the BirdReturns program, and Hallstein estimates that it will ultimately cost about $10 million to $30 million per year to create roughly 600,000 acres of pop-up wetlands. That’s a good deal compared with the billions it would take to buy that much land outright. But the dynamic, adaptable nature of the program brings other benefits, too.
“The problem with the capital-intensive model that’s about buying property or easements, permanently, is you have to get it absolutely right,” says Hallstein. “You’re stuck with what you bought.”
With this program, there’s far more flexibility to experiment, figure out what works best and adjust accordingly.
Now that the concept of pop-up habitat is being test-flown in the Sacramento Valley, the Conservancy is carrying out an ambitious monitoring program to understand exactly what types of rice-field habitat will provide the greatest benefit for the birds.
That monitoring, as Reynolds put it, “involves five field scientists, running as fast they can.”
of birds. It was a lot of ground to cover, and the team was constantly on the move.
After scoping out the birds and the water level in a rice field, Golet dictated notes into his iPhone. “We sync it, and it goes to the cloud,” he said. “It’s kind of magic.”
He checked his watch, and took off running again.
The Conservancy is already figuring out how it might expand BirdReturns beyond the Sacramento
Valley. This year, the team is running field trials to see how corn and alfalfa fields can be better managed for birds, which could pave the way to take the program to the southern half of the Central Valley—the San Joaquin Valley, another agricultural bastion. And by working with Cornell to develop models that predict the birds’ population abundance, the team is further refining its understanding of what kinds of habitat are the best investment for the future.
“The next version—sort of like Version 2.0—is to take the results of the monitoring work, and the abundance modeling, to create an index of habitat value,” says Hallstein. With that ranked index of what habitat works best for specific species, it will be possible “to start developing payment structures that preferentially pay for the ultimate outcome that we’re concerned about, which is the birds.”
It should soon also become possible to make the program even more responsive to real-world conditions as they vary from week to week during the migration. “We know very precisely—and almost in real time—which species of birds are coming down through the Pacific Flyway and what exact habitat they need,” Hallstein says. With that knowledge, adds Reynolds, “we could actually prepare for birds coming in, and dial up dynamic habitat in real time. That’s where we’re headed. That’s the vision.”
In late afternoon, a bald eagle soars over ecologist Greg Golet, who is tallying birds in a rice field. Looking up, he says, “Oh, that’s awesome.”
After a few more minutes, Golet ticks items off his task list and turns to leave. “All right,” he says, “I think we’re good.”
As he walks back down a levee to his car, the sound of wings on the wind fills the air. Flock after flock of ibises cruise by overhead. In the fading light, the flooded rice fields begin to turn the exact color of the sky—and suddenly, the world seems to double in size.
“You feel like this is a glimpse of the yesteryear of the valley, before it was all altered,” Golet says. “You can imagine that’s the kind of spectacle you would have seen, but maybe tenfold. That’s why it’s so cool to be out here now, because there’s still a lot going on. If we didn’t see what’s happening today, we wouldn’t even be able to imagine what it was like.”
Doug Thomas, the farmer who has kept his fields wet for the shorebirds, echoes the sentiment. “This is the story, right here,” he says, as skeins of geese fly overhead while the frosted crowns of Lassen Peak and the Sierra Buttes shine
in the distance. “It’s the future of these birds.” •