Tidal marsh wetlands worldwide have been lost due to human impacts. Tidal marshes are critical to many wildlife taxa and have become the focus of many restoration projects. In the Suisun Marsh of California, part of the San Francisco Bay Estuary and the largest brackish marsh on the U.S. Pacific coast, tidal marsh restoration relies on the conversion of existing non-tidal managed wetlands in order to create new tidal marsh. These restorations can cause conflicts among stakeholders and species that win or lose depending on identified restoration priorities.
USGS scientists analyzed the use of tidal marsh and managed wetlands in the Suisun Marsh by dabbling ducks. The analysis examined 422,017 locations within the Suisun Marsh by six dabbling duck species (N = 315 individuals) tracked with GPS-GSM 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 pondlike 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.”
Habitat types and associated duck GPS locations in Suisun Marsh, California. Percentages represent the proportion of Suisun Marsh that the habitat constitutes.