Tidal marsh wetlands across the world have been lost due to human impacts. Because these marshes are critical to myriad wildlife taxa, they are often the focus of restoration projects. The Suisun Marsh of California, which is part of the San Francisco Bay Estuary and the largest brackish marsh on the United States Pacific Coast, is a critical stopover for thousands of migratory waterfowl transiting along the Pacific Flyway. Here tidal marsh restoration relies on the conversion of existing non-tidal managed wetlands to create new tidal marsh. These restorations can cause conflicts among stakeholders and species that win or lose depending on identified restoration priorities.
U.S. Geological Survey (USGS) scientists analyzed how dabbling ducks use tidal marsh and managed wetlands in the Suisun Marsh. The analysis examined 422,017 locations within the Suisun Marsh by six dabbling duck species (N = 315) tracked with Global System for Mobile Communications (GSM)-Global Positioning System (GPS) units. The study area comprised approximately 47% managed wetland and 14% tidal marsh. Results indicate that the dabbling ducks used the managed wetlands ~98% of the time compared to 2% in tidal marsh. Even though the ducks preferred managed marsh, almost half of the tracked ducks did use tidal marsh at some point. When the ducks used tidal marsh, they preferred pond-like features.
Managed wetlands are vital to dabbling ducks. However, when managed wetlands are converted to tidal marsh, incorporating pond features may make tidal marsh wetlands more attractive to waterfowl and provide multi-species benefits. While waterfowl are presently common, previously seen calamitous population declines can be avoided through informed ecosystem-based management that promotes species richness and biodiversity and helps “keep common species common.” The associated manuscript is available here.
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Habitat types and associated duck GPS locations in Suisun Marsh, California. Percentages represent the proportion of Suisun Marsh that the habitat constitutes. The associated manuscript is available here.
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