Using ricelands to provide temporary shorebird habitat during migration.

To help mitigate large wetland losses in California, The Nature Conservancy launched a dynamic conservation incentive program to create temporary wetland habitats in harvested and fallow rice fields for shorebirds migrating along the Pacific Flyway. Farmers were invited to participate in a reverse auction bidding process and winning bids were selected based on their cost and potential to provide high quality shorebird habitat. This was done in 2014 and 2015, for separate enrollment periods that overlapped with spring and fall migration, both before and after the traditional post-harvest flooding period. To assess the success of the program, we monitored shorebird use of fields that were enrolled (treatments), and others that were subject to typical rice farm management (controls). To put these observations in context, we used satellites to simultaneously monitor the extent of shallow-water habitat across the ~215,000 ha of ricelands in the area. Results showed that providing habitat during migration, when it is typically unavailable in rice fields, yielded the largest average shorebird densities ever reported for agriculture in the region. Treatment fields had significantly greater shorebird density, richness and diversity than control fields in both spring and fall (especially September-early October, and late March-early April), but in fall the difference was greater. Shorebird responses to habitat provisioning, and regional habitat conditions, were variable from year to year, and highly dynamic within a given season. Overall, shorebirds densities were found to be negatively related to the total amount of flooded habitat in the rice landscape. Factors that affected habitat availability included allocation schedules of water deliveries from reservoirs, and rainfall patterns, both of which were influenced by drought. Collectively, these results suggest that appropriately managed agricultural lands have great potential to provide high value habitat for shorebirds during times of habitat deficit, including migration, and that fall may be a particularly impactful time to create additional habitat. Migratory species face great challenges due to the climate change, conversion of historical stopover sites, and other factors, but dynamic conservation programs offer promise that, at least in certain instances, their needs can still be met.