When they're flying south for the winter, birds need to rest their weary wings—preferably somewhere with food and water. But due to California's agricultural development (not to mention its record-breaking drought), their preferred West Coast wetland stopovers are few and far between. So Matt Merrifield, a geographer with the Nature Conservancy of California, dove into geospatial data to help develop an alternative. The answer: flooded rice paddies.

After the September harvest, farmers flood their fields to break down leftover rice straw. That's water—but not on the right schedule. “We had to identify, very specifically in time and space, where there were a lot of birds but not a lot of water,” Merrifield says. So he overlaid migration data—crowdsourced from birders—with satellite images showing farmland water use. Then the Conservancy paid rice growers in the overlapping areas of California's Central Valley to keep certain fields flooded when the birds arrive in October.

The result: about 10,000 acres of popup wetlands for birds to visit en route from Alaska to South America, sited underneath them at the exact time they need a landing. “Eventually we want to do this not only in the Central Valley but up and down the Pacific Flyway,” Merrifield says. That should make for some happy birds.