Bio227:5: The California Clapper Rail

THE CALIFORNIA CLAPPER RAIL

Rallus longirostris obsoletus

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The California Clapper Rail (Rallus longirostris obsoletus) is an endangered bird ranging from 13-19 inches from bill to tail, sporting an olive brown to cinnamon color, and a long bill. Their colors blend into the pickleweed and cordgrass found in their prime habitats, keeping them hidden from potential predators.The existing populations occur in tidal and brackish marshes around the San Francisco Bay estuary where there are unrestricted daily tidal flows, sufficient food supply, proper nesting, and areas for refuge. However, the historical range of the Clapper stemmed from Morro Bay to Humboldt Bay.

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The Clapper Rail diet consists mostly of spiders, amphipods, yellow and striped shore crabs, clams, and the introduced horse mussel. The introduced mussel often traps the foot or bill of the Rail as they try to pry it open. The species’ habitat has undergone extreme alterations due to human impacts that has reduced their original 190,000 acres of tidal marsh to the existing 40,000 acres that exist today.

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The species was listed as endangered by the Federal government in 1970 and soon added to the State endangered species list in 1971. The listing is categorized as the priority 3C, “constituted by its high degree of threat, potential of recovery, and taxonomic standing as a sub species.” The C represents that conservational needs of the species may conflict with economic development.

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With the introduction of industrialization and urbanization in California, came the destruction of tidal marsh. The main factors contributing to the Clapper Rail’s endangerment are habitat loss, habitat degradation, fragmentation, loss of buffer zones, human disturbance, waste water discharges, introduced plants, increased predation due to the availability of man-made structures, increased disturbance from recreational access, reduced habitat quality, and contamination of marsh sediments. California’s coastal wetland habitats were reduced by 90 percent beginning in the 1800s.

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Non-native predators have also caused a significant decline in Clapper Rail populations as red foxes, Norway rats, and feral cats prey on these birds and their eggs. Invasive plant species have also had a significant impact on these bird populations as Spartina alterniflora Spartina foliosa have altered the physical and biological structure of the tidal wetlands making it more difficult for Clappers to hide from predators and find food. According to the California Department of Pesticide Regulation, rail eggs have been found containing high levels of mercury and selenium due to sewage and industrial discharges.

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The recovery plan for the Clapper Rail consists primarily of restoration to its habitat, using an ecosystem-based approach. Focusing on the restoration of tidal marshes and their surrounding wetlands would provide the foundation in food needs, shelter, and breeding requirements. In 2003, 16,500 acres of salt ponds were donated to the California Department of Fish and Wildlife and the U.S. Fish and Wildlife Service. This land will be restored in phases back to tidal marsh and pond habitats. This land donated by Cargill Incorporated, will account for the largest tidal restoration plan in west coast history.