Collaborative Research: Managing across scales: Can habitat restoration reverse declines in salt marsh birds?

About This Grant

Tidal marshes are one of the most biologically productive ecosystems on earth, supporting critical ecosystem services including coastal storm defense, fisheries support, and unique biodiversity. Yet, tidal marshes are severely threatened by coastal flooding. Trapped tidal floodwaters break-up marsh meadows (“ponding”), and cause remnant marsh grass to become sparse and stunted. Healthy meadows are needed by marsh-breeding birds to prevent nest flooding, an increasing cause of nestling mortality leading to species declines as fast as 9% per year. To save marsh birds, practitioners have proposed a novel technique to drain trapped floodwaters by creating shallow channels (“runnels”). However, effective methods are still being developed, and whether this approach to restoration will work for tidal marsh birds is unknown. This project will examine marsh bird responses to ponding, measure ecosystem responses to runnels, and provide design metrics and restoration targets for runnels. In 2025, a National Audubon Society-led partnership (“Marshes for Tomorrow”) set an ambitious goal to restore thousands of acres of tidal marsh in Maryland by 2035. Using results from this project, Towson University, University of Maryland, and Audubon will take action toward this goal through evidence-based restoration. The project will produce technical protocols for practitioners, make public outreach presentations, and train undergraduate and graduate students in ecological science and conservation practice. The project will also engage with local communities to choose restoration sites, and share science-based management options with landowners to reduce flooding of their marshlands. This project investigates relationships between ecosystems, landscape-scale patterns of fragmentation (ponding), and consequences for tidal marsh bird persistence — integrating across spatial and temporal scales to link ecosystem function to bird population demographics. The study will focus on two tidal marsh endemics, the rapidly declining Saltmarsh Sparrow, and the Seaside Sparrow. Surveys and experiments will be conducted in twelve tidal marshes in the Maryland-portion of the Chesapeake Bay. This project includes three technical approaches: 1) large-scale habitat and breeding bird surveys using field studies and remote-sensing, 2) an ecosystem-scale restoration experiment monitored using field surveys and biogeochemical analyses, and 3) microhabitat studies using field-based nest observations and mesocosm experiments on plant and soil recovery. The project will test the hypothesis that tidal marsh bird densities and nesting success decline non-linearly as ponding increases (exploring the presence of tipping-points) and will derive habitat indices from remote-sensing data to direct site-selection and set target metrics for habitat recovery after restoration. Audubon will conduct hydrologic restoration at an expansive, moderately fragmented marsh that researchers will use as a whole-ecosystem experiment with a before-after-control-impact design. By assessing variation in water, soil, and plant responses to runnels the project will identify specific characteristics favorable for restoration. Spatial and temporal patterns in marsh bird responses to pond-fragmentation, ecosystem responses to restoration, and subsequent implications for habitat quality will inform basic science on resilience and recovery. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.