The California Clapper Rail, Salt Marsh Native

By Sharol Nelson-Embry, Naturalist, East Bay Regional Park District

Like two rocks struck together, the California clapper rail's mating calls reverberate from salt marsh habitat around San Francisco Bay.

Our bay marshes are the last places on earth you can find the California clapper rail, an endangered species. While some other marsh birds migrate to far-flung locations around the hemisphere, the clapper rail makes its year-round home here.

The clapper rail is roughly the size of a small chicken, about 13 inches, with a rounded body, but thin from side to side.

Being “thin as a rail” helps the bird slip nearly undetected through thick marsh vegetation. Its cinnamon-brown color helps it camouflage with its surroundings. Sometimes it seems like clapper rails are so used to being invisible that even when standing in the open, they act as though no one can see them. A long neck and bill help it feed on a variety of marsh animals, including crustaceans, mussels, clams and worms.

They mate for the season and construct a nest among cordgrass and other tall marsh plants. The nest often has a woven cover to protect the eggs and young from predators and sometimes is built to float up on the tide while tethered around surrounding plants. The parents both sit on the nest with an average of seven eggs, then split up to care for the first hatchlings while the other eggs continue being incubated.  The young are able to walk, find food and swim shortly after birth, with the parent close by providing some protection and warmth.

California clapper rails are nearing extinction for a variety of reasons. In the mid-1800s these “marsh chickens” were hunted as food for the new settlers and miners coming to the Bay Area during the Gold Rush.

There were reports of 1,000 clapper rails per week being brought to market. After the 1916 Migratory Bird Treaty banned hunting rails and other birds, their population rebounded. 

In the 1930s through the '60s, though, salt marshes around the Bay—prime rail habitat—began being drained, diked and filled to create areas for housing and commerce. Alameda’s South Shore, Alameda Point and Bay Farm Island were once extensive salt marsh areas. Save the Bay and the creation of the Bay Conservation and Development Commission (BCDC) helped preserve some remaining habitat.

The red fox, a non-native predator introduced to the Bay Area in the ‘80s, further reduced California clapper rail numbers. The fox population was reduced in the mid '90s and continues to be monitored. 

Currently clapper rail populations are falling due to efforts to control a non-native species of marsh grass, Spartina alterniflora and its hybridized subspecies. We’ve lost our rails at Alameda's Elsie Roemer Bird Sanctuary, but a small population remains in the marshes around San Leandro Bay. 

You can go to Arrowhead Marsh at the Martin Luther King, Jr. Regional Shoreline during high tide and often see and hear this endangered bird. For more information, call the Crab Cove Visitor Center at 510-544-3187 or see www.ebparks.org for programs and parks you can visit.

Sharol Nelson-Embry is the supervising naturalist at Crab Cove Visitor Center.