On a warm, sunny afternoon in late November, Roger Cornwell stopped his pickup near the edge of a harvested rice field to avoid spooking a great blue heron standing still as a statute, alert for prey. He pointed to a dozen or so great egrets at the opposite end of the field as a chorus of killdeer sang a high lonesome tune in the distance.

“We started bringing in the water this morning,” said Cornwell, general manager of River Garden Farms, which grows rice, alfalfa, corn, walnuts and other crops on 15,000 acres just west of the Sacramento River, in California’s Central Valley. “When we push water across a field, we’ll have tons of egrets in it because the mice and moles are being flushed.”

In the Central Valley, where agricultural and urban development have claimed 95 percent of the region’s historic wetlands, flooded croplands provide food and habitat that help egrets, sandhill cranes and other iconic water birds get through the winter. Inundating fallow fields mimics the way rivers breached their banks 150 years ago, before engineers built thousands of miles of levees, and funneled Sierra Nevada snowmelt through a vast network of aqueducts and canals to farmers and more than 27 million Californians.

But many farmers are moving toward wine grapes, olives and other “permanent crops” that don’t provide the same habitat benefits as row crops. And now these land use changes, combined with the uncertain effects of a warming world, have left scientists scrambling to safeguard critical habitat in one of most important wintering regions for water birds in North America.

“Our wetland birds are among those showing the biggest declines,” said Khara Strum, who works with Cornwell as conservation manager for Audubon’s Working Lands Program.

Read the full article about finding a buffer for migratory water birds by Liza Gross at Inside Climate News.