Habitat & Wildlife at Sweetwater Marsh Unit

Coastal Salt Marsh
The main habitat in this refuge is coastal salt marsh salt marsh
Salt marshes are found in tidal areas near the coast, where freshwater mixes with saltwater.

Learn more about salt marsh
. This area is full of life—it supports small creatures like invertebrates and young fish, and gives birds a place to nest, find food, and stay safe during high tides. Some special birds that live here include the endangered light-footed Ridgway’s rail and the Belding’s savannah sparrow. Ridgway’s rails almost completely rely on salt marshes, especially thick patches of cordgrass, for feeding, resting, and nesting. Belding’s savannah sparrows are found throughout the marsh. An endangered plant called salt marsh bird’s beak also grows here.

Mudflats and Wintering Birds
The mudflats and salt marshes in the Sweetwater Marsh Unit are important winter homes for many shorebirds, such as long-billed curlews, whimbrels, and red knots.

Other Habitats
Smaller areas of the refuge include wetland-to-upland transition zones and maritime succulent scrub. These areas support several rare plants. Another spot, called the D Street Fill, was created in the 1960s when tidelands were filled with dredged material. Today, it provides nesting sites for ground-nesting birds like California least terns, horned larks, and killdeer. Western snowy plovers used to nest here too, but none have been seen since 2000.