Conservation objectives to eliminate food shortages for shorebirds in California’s Central Valley

What is it about?

Together with Central Valley Joint Venture partners, we defined a long-term goal of supporting double the number of shorebirds that use the Central Valley while migrating or over-wintering (July - May). In this paper, we identified how much additional shorebird habitat would be needed to meet this long-term goal, and when during the non-breeding season it is most critical. Our analysis accounted for habitat provided by wetlands and agricultural fields that are flooded post-harvest (especially rice and corn), the timing of flooding in each of these habitat types, the depth of flooding that allows shorebirds to access these habitat types, and the average amount of food energy per acre of flooded habitat (coming from invertebrates in the ground). At current population sizes, we identified a food supply shortage during the fall (Aug-Sept) when relatively little flooded habitat is typically available. If shorebird population sizes were doubled, the fall food shortage would increase and there would also be a substantial shortage during the spring (mid-Mar through Apr), after flooded agricultural fields and seasonal wetlands are typically drawn down. To guide wetland management and restoration plans, we estimated the amount of additional flooded wetland habitat that would be needed to eliminate these food shortages in the fall and spring.

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Why is it important?

Central Valley wetlands and flooded agriculture are of international importance to shorebirds, hosting over 500,000 migrating and wintering shorebirds each year. Historically, there was 10 times the current amount of flooded habitat, and the Central Valley likely supported more than double the current number of shorebirds. By establishing a long-term conservation goal of doubling the current number of shorebirds using the Central Valley during the non-breeding season, local agencies and organizations can work together to prevent further loss and degradation of shorebird habitat in the Central Valley and to reduce the impacts of historical wetland habitat losses. These efforts would contributing to more resilient shorebird populations in the Pacific Americas Flyway, as well as provide benefits to the people of the Central Valley. Our analysis provides estimates of when additional habitat is most critical to meeting these long-term conservation goals, and our modeling approach provides an effective way of examining the potential outcomes of changes in wetland and agricultural flooding practices in this complex system.

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