U.S. Fish & Wildlife Service

Sacramento Fish & Wildlife OfficeServing the people, conserving the fish, wildlife, and plants of California

A Unit Of The Pacific Southwest Region

Species Information

Photo of Ridgway's Rail

Photo Credit: USFWS

Ridgway’s Rail

(previously called California Clapper Rail)

Rallus longirostris obsoletus

Basic Species Information

STATUS

Endangered. This species is in danger of extinction throughout all or a significant portion of its range.

DESCRIPTION

Ridgway’s rail is one of the largest rails. It is 32-47 cm (13-19 inches) from the tip of its bill to the tip of its tail. It looks like chicken with a long, slightly downward-curving bill. Its upper parts are olive-brown. Its breast is cinnamon-buff colored and its dark flanks are crossed by white bars and white undertail coverts that are often exposed when the bird is agitated.

Male and female rails differ only in size. In general, males are slightly larger. Juveniles have a paler bill and darker plumage, with a gray body, black flanks and sides, and indistinct light streaking on flanks and undertail coverts.

Rails are secretive and hard to see in dense vegetation. They often roost at high tide during the day.

When evading discovery, they typically freeze, hide in small sloughs or under overhangs, or run rapidly through vegetation or along slough bottoms. They prefer to walk or run rather than fly or swim. Once flushed, they can frequently be approached because they normally fly only a short distance before landing. They can swim well, although swimming is only used to cross sloughs or escape threats at high tide.

In July 2014, the North American Check-list Committee upgraded the California Clapper Rail to its own species, and renamed it the Ridgway's Rail. The complete story is in the Winter 2014 issue of Tideline.

FOOD SOURCES

Ridgway’s rails are most active in early morning and late evening, when they forage in marsh vegetation in and along creeks and mudflat edges. Mostly things like mussels, crabs and clams.

HABITAT

Ridgway’s rails occur within a range of salt and brackish marshes. In south and central San Francisco Bay and along the perimeter of San Pablo Bay, rails typically inhabit salt marshes dominated by pickleweed (Salicornia virginica) and Pacific cordgrass (Spartina foliosa). Pacific cordgrass dominates the middle marsh zone throughout the south and central Bay.

In the north Bay (i.e., Petaluma Marsh, Napa-Sonoma marshes, Suisun Marsh), rails also live in tidal brackish marshes that vary significantly in vegetation structure and composition. Use of brackish marshes by clapper rails is largely restricted to major sloughs and rivers of San Pablo Bay and Suisun Marsh, and along Coyote Creek in south San Francisco Bay. Rails have rarely been recorded in nontidal marsh areas.

MATING

The breeding season begins by February. Nesting starts in mid-March and extends into August. The end of the breeding season is typically the end of August, which corresponds with the time when eggs laid during renesting attempts have hatched and young are mobile. Clutch sizes range from 5 to 14 eggs. Both parents share in incubation and rearing.

RANGE

Ridgway’s rails are now restricted almost entirely to the marshes of the San Francisco estuary, where the only known breeding populations occur. In south San Francisco Bay, there are populations in all of the larger tidal marshes. Distribution in the north Bay is patchy. Small populations are widely distributed in the San Pablo Bay and Suisun Marsh.

PREDATORS

Throughout the Bay, the remaining clapper rail population is besieged by mammal and bird predators. At least twelve native and three nonnative predator species are known to prey on the rails or their eggs. Encroaching development not only displaces predators from their natural habitat, but also adversely affects higher order predators, such as coyotes, which would normally limit population levels of middle and lower order predators, especially red foxes. The proliferation of nonnative red foxes into tidal marshes of the South Bay since 1986 has had a serious effect on rail populations.

Nonnative Norway rats (Rattus norvegicus) are predators of rail nests. Placement of shoreline riprap favors rat populations, which results in greater predation pressure on clapper rails, especially in narrow, linear strip marshes.

In addition, feral cats are a major problem. Cats kill millions of birds per year.

THREATS

Primary threats include:

  • Historical and current habitat loss and fragmentation due to urban development, agriculture, and diking related to duck hunting
  • Altered hydrology and salinity
  • Nonnative invasive species
  • Inadequate regulatory mechanisms
  • Disturbance
  • Contamination
  • Sea level rise due to climate change
  • Risk of extinction due to vulnerability of small populations in the face of random naturally occurring events.

Much of the East Bay shoreline from San Leandro to Calaveras Point is rapidly eroding, and many marshes along this shoreline could lose their clapper rail populations in the future, if they have not already. In addition, an estimated 600 acres of former salt marsh along Coyote Creek, Alviso Slough and Guadalupe Slough, has been converted to fresh- and brackish-water vegetation due to freshwater discharge from South Bay wastewater facilities and is of lower quality for clapper rails.

The suitability of many marshes for clapper rails is further limited by their small size, fragmentation, lack of tidal channel systems and other habitat features. In addition, the difference between high and low tides is much greater in the south Bay than in San Pablo or Suisun bays. Many marshes are completely submerged during high tides and lack sufficient escape habitat. This probably results in nesting failures and high rates of predation. Larger tracts of habitat are needed to maintain stable populations.

Predation impacts are made worse by a reduction in high marsh and natural high tide cover in marshes. Hunting intensity and efficiency by raptors on clapper rails also is increased by electric power transmission lines, which crisscross-cross tidal marshes and provide otherwise-limited hunting perches. Mercury accumulation in eggs is perhaps the most significant contaminant problem, with the South Bay containing the highest levels. Mercury is extremely toxic to bird embryos.

WHAT YOU CAN DO

There are many things you can do to protect birds. Here is some information on migratory bird conservation. It is about migratory song birds. But much of it applies to all birds.

Keep your cat inside. Even well-fed cats kill birds. It is just their nature to hunt. Living indoors is also much safer for the cats themselves. When you go to the beach, pay attention to signs warning you that birds are nesting. Many shore birds nest right on the beach. They are easily disturbed. Don't let your dog chase or bark at them.

Whenever you go to natural areas, observe any signs telling you how to protect wildlife and plants.

See What You Can Do to Help Wildlife and Plants (201 KB PDF) for more ideas.

The California Clapper Rail can be seen at the following National Wildlife Refuges

Last updated: November 30, 2017