Funny what a little rain can do. Last summer, the Grassland Ecological Area — a sprawling wetland tucked into agricultural fields near Los Banos in California’s Central Valley — was bone dry. For the hundreds of thousands of traveling birds that stopover in the wetlands each year, it was if someone had boarded up the last roadside Denny’s.

The numbers of Mallard ducks began to plummet by 40 percent, much to the chagrin of the area’s numerous duck hunting clubs. Most of the other 270 avian species frequenting the area followed.