YUBA CITY (AP) — For the swirling flock of migrating shorebirds banking to a landing in California’s Central Valley, a recently flooded rice field is providing a new kind of triage station during a drought that’s drastically reducing places where they can rest on their long journeys.The new arrivals to the field — hundreds of them — are dowichers, says conservationist Greg Gulot, standing on a dirt berm and focusing his binoculars to identify a wading bird that is one of the first to fly south in an annual migration that brings 350 species to California’s Sacramento and San Joaquin valleys.With millions of birds on their way from the Arctic and subarctic and the drought cutting critical wetlands to as little as one-sixth, the field is one of the first to come on line this fall under a new program of “pop-up” habitats.Conservationists are temporarily renting 14,000 acres from rice farmers and flooding them just long enough to give the migrating birds the rest and food they need to survive their flights.Within hours of workers flooding the field two weeks earlier, hundreds of migrating birds appeared.“It was incredible,” says biologist Simon Avery, a field monitor for the Nature Conservancy, which conceived and operates the pop-up rented wetlands, first tested last spring. “The birds are flying high over our heads, and they see water and come down.”With severe drought covering 95 percent of California, pop-up wetlands are one of the few tools that conservationists and others have to help stave off what wildlife refuge managers are warning could be major bird die-offs this fall and spring as waterfowl and shorebirds crowd too few acres of wetlands.Without the pop-up habitat, “It’d be impossible” to provide significant replacement for the hundreds of thousands of wetlands that drought has taken offline, says Gulot, who shouts back and forth with Avery as they spot clusters of birds. “We would feel helpless.