Each year, 181 species of waterfowl, shorebirds and riparian birds flock to California’s Central Valley to nest between November and March. The space they roost in is already limited: There are just 19 wetlands, comprised of National Wildlife Refuges and State Wildlife Areas, spread across little more than 270 square miles in the valley’s 22,500-square-mile expanse.

But over the past five years during the state’s historic drought, those birds have returned, only to find once watery areas no longer suitable for nesting. If dry conditions persist, the little remaining space could disappear.