Suisun Marsh Waterfowl and Waterbird Studies

Science Center Objects

Suisun Marsh provides critical habitat for wintering and breeding waterbirds in California. USGS WERC collaborates with the California Department of Water Resources to examine trends in bird declines and to assess the habitat factors driving long-term survival of waterfowl, rails, and other birds in this important area.

Gadwall ducklings in nest

Gadwall ducklings in nest, Suisun Marsh, CA. (Credit: Sarah Peterson/USGS. Public domain.)


Suisun Marsh, California has a long history as an important area for waterfowl. Over the past several years, however, waterfowl populations have been declining, indicating that fewer dabbling ducks and geese are choosing to winter in Suisun Marsh. This region also supports among the highest densities of breeding ducks in North America, and plays an important role in supporting duck populations within California.  

With more than 90 percent of California’s wetlands lost, Suisun Marsh represents one of the last remaining contiguous wetland habitats in the state. In order to understand and manage waterbird populations and habitats in Suisun Marsh, the California Department of Water Resources has partnered with the USGS Western Ecological Research Center and other project collaborators.

This project seeks to:

  1. Conduct waterfowl abundance surveys to estimate an index of population size for wintering waterfowl in Suisun Marsh.
  2. Examine waterfowl habitat use and movements using telemetry.
  3. Examine waterfowl body condition and assess temporal changes.
  4. Examine the nesting ecology of waterfowl and long-term trends in nest survival and nest density.
  5. Examine duckling survival, brood ecology, habitat use, and movements in relation to wetland habitats and salinity.
  6. Assess long-term trends in waterfowl demographic rates and population viability.
  7. Assess the value of food types and different wetland habitats to waterfowl in Suisun Marsh, and estimate carrying capacity of Suisun Marsh for waterfowl.
  8. Develop and conduct continuous rail (California Ridgway's Rail and Black Rail) surveys using acoustic recording devices within Suisun Marsh.
  9. Examine rail habitat availability and develop metrics of habitat quality from habitat use and movements using telemetry where appropriate.
Hen in Suisun Marsh

Hen in Suisun Marsh, CA. (Credit: Sarah Peterson/USGS. Public domain.)