Consider how Airbnb works. Think of Minneapolis during the coming Super Bowl, when hotel rooms are scarce and residents will be enticed to rent their homes to football fans. Something like that happens in the environmental realm, too: There is a surge in demand for protected land when migratory birds are passing through an area or a threatened species is breeding.

In the United States, the nonprofit Nature Conservancy has been a pioneer in bringing the “sharing economy” business model to conservation. It has been temporarily expanding wetlands for migratory birds in California’s Sacramento Valley since 2014. In early fall, when birds head south for the winter, and again in early spring on their return journey, birds need larger protected areas than the current mix of parks and nature preserves allows, as the website Howstuffworks reported in August.

The big insight was realizing “we could use a rent rather than buy model,” said Mark Reynolds, an ecologist with the Nature Conservancy, which pays rice farmers to flood their fields for the few crucial weeks each fall and spring. Rice growers routinely flood their fields for irrigation and to decompose crop residue after harvest; through the conservation program, named BirdReturns, they do so during periods when the fields would have been dry.

A team of ecologists and economists figured out how much to compensate the farmers for this change. They ran “reverse auctions” in which landowners specified the lowest payment that would entice them to flood their fields for a given four- to eight-week period.

This auction system adjusts payments to farmers’ costs. For example, flooding during the end of the spring migration season is trickier to fit into an annual rice-growing schedule, so bids — and payments — are higher then. The auction model is also flexible when the weather fluctuates. The early years of the program occurred during California’s prolonged drought, but abundant rainfall in 2017 meant that BirdReturns could dial back the amount of pop-up wetland it procured this year.