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Every winter, millions of migrating birds come to the Sacramento Valley, but now these birds may find the marshes and flooded rice fields dry.

The marshes and flooded rice fields here are a stopping point for the birds along the Pacific flyway, and scientists are now putting GPS trackers on birds to learn how they’re reacting to the dry environment.

“A migratory pathway for waterfowl and shorebirds that are coming from northern areas, moving into the Central Valley and looking for spots to feed, to rest and continue on their journey farther south to warmer areas in the winter, and then heading back north again in the spring,” Samantha Arthur, Audubon California Working Lands Program Director, said.

Arthur says ninety percent of the region’s wetlands have been lost to development over the past one hundred years.

“So that remaining ten percent of wetlands is so critical in this area. And then luckily, we also have rice that provides a compliment to those wetlands,” Arthur continued.

“Here in the winter, when a rice farmer puts water on their field, they’re decomposing the leftover rice straw. But it’s also providing shallow habitat for shorebirds and waterfowl that are migrating through the Pacific flyway, so it’s a really important resource for those migratory birds,” Arthur said.

But the drought of the past three years is shrinking the amount of wetland available to the birds.

Many rice farmers, for lack of water allotments, especially along the Sacramento River, have let their land lie fallow.

The land where birds would normally flock to feed is now dry and desolate.

Maps of the areas where rice fields are located show the difference between a normal season, when a lot of land would be flooded, and recent years when it is 90% less land flooded, leading to a massive loss of bird habitat.

On top of that, many areas of natural wetland are shrinking, including a section of the Sacramento National Wildlife Complex near Willows that has gone completely dry.

“Normally the Central Valley will support over eight million non-breeding waterfowl. This year I think we’re going to have a tough time supporting that level,” Michael D’Errico, a U.S. Fish and Wildlife Service Biologist said.

D’Errico evaluates how wildlife is impacted by the changing conditions at the preserve.

“The reduced wetland footprint and the reduced rice footprint has really impacted how the birds are using the Sacramento Valley,” D’Errico said. “And actually, acquiring the resources necessary to get through the overwintering period is going to be pretty significant this year.”

Arthur says that another risk is that the birds crowd into smaller areas of habitat and have increased disease transmission.

Rodd Kelsey, Ph.D. Nature Conservancy Water Program, points out that some of these birds travel ten thousand miles a year.

“That takes a lot of fuel. And so, when they don’t have enough habitat, we expect they either don’t breed very well, or they don’t survive migration. And that’s what we’re trying to get a handle on,” Kelsey said.

Audubon California and the Nature Conservancy are two of several organizations working together to study the birds by putting GPS transmitters on a select sample.

“We’re going to be able to see their annual cycle and whether they’re having a hard time or not,” Kelsey said.

“The question is, when birds come down from their breeding grounds in the Arctic and Alaska and Russia, they come all the way down here and they’re on the west side of the valley and there’s no food, what do they do?” Luke Matthews, California Rice Commission Wildlife Programs Manager, said.

Matthews is helping manage a separate study with funding from the Department of Water Resources, tracking 160 birds of four different species of ducks and geese.

“We said, ‘we need to figure out what are the impacts of this major change?’ it’s something I’ve never seen in my thirty-plus year career,” Michael Casazza, USGS Research Wildlife Biologist, said.

Casazza is a partner in the study, looking at the real-time data provided by these lightweight solar-powered collars and what are known as backpack transmitters.

“It just sits on the bird’s back like a backpack. We have kind of an elastic harness,” Casazza said.

The data from the transmitters will show the scientists the impacts of the lack of food, water and habitat when these rice fields are dry.

“We’re going to be getting this data for weeks and months and even years to come,” Matthews said.

Some waterfowl live to be ten, even twenty years old. The solar-powered transmitters are designed to last the full lifetime of each bird.

This study is just a few weeks old, but it’s already revealing.

“The birds come to the west side where they normally thrive. They’re finding it dry and void of food. And then they just shift, and they go to the east side of the valley. Or some of them are going down into the Delta,” Matthews said.

The researchers hope the data will help policymakers understand the impacts of drought on bird populations and the role of rice fields as bird habitats.

It’s about having sound science to inform future preservation efforts and water allocations.

“And so, when you have the money to put toward good things on the landscape, you want to be able to focus on something you know is going to work,” Casazza said. “I think it would be criminal for us not to do it, right? Not to figure it out while we can.”

“People come from all over the world to see the spectacle of migration here,” Kelsey said. “Who wants to live in a world where all these birds disappear?”