Ridgway's rail

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Ridgway's rail
Ridgway's Rail (24515510911).jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Rallidae
Genus: Rallus
R. obsoletus
Binomial name
Rallus obsoletus
Ridgway, 1874

Rallus longirostris obsoletus
Rallus crepitans obsoletus


Ridgway's rail (Rallus obsoletus) is a near-threatened species of bird. It is found principally in California's San Francisco Bay to southern Baja California. A member of the rail family, Rallidae, it is a chicken-sized bird that rarely flies.

This species is closely related to the clapper rail, and until recently was considered a subspecies. [2] It has a long, downward curving bill and is grayish brown with a pale chestnut breast and conspicuous whitish rump patch. The population levels of Ridgway's rail are precariously low due to destruction of its coastal and estuarine marshland habitat by prior land development and shoreline fill. It has year-long, circadian activity and is most vocal nocturnally and crepuscularly. [3]


Pickleweed Creek, the upper arm of Richardson Bay looking toward Bothin Marsh Pickleweedecreekerazorback.jpg
Pickleweed Creek, the upper arm of Richardson Bay looking toward Bothin Marsh

Ridgway's rail forages at the upper end of, along the ecotone between mudflat and higher vegetated zones, and in tidal sloughs. Mussels, clams, arthropods, snails, worms and small fish are its preferred foods, which it retrieves by probing and scavenging the surface while walking. The bird will only forage on mudflats or very shallow water where there is taller plant material nearby to provide protection at high tide. At such high tides it may also prey upon mice, and has been known to scavenge dead fish. [4]

One of the largest population of Ridgway's rails is in San Francisco Bay, where a total of about 1100 are resident. [5] The photo above right was taken of a Ridgway's rail at the San Francisco Bay perimeter near the Dumbarton Bridge; the Don Edwards San Francisco Bay National Wildlife Refuge in the area provides protected habitats for this and other native species. Other frequent sightings of this species around the San Francisco Bay include the Napa Sonoma Marsh, Bothin Marsh in Mill Valley, Gallinas Creek in San Rafael, Arrowhead Marsh and Damon Marsh in Oakland, the Palo Alto baylands, [6] Charleston Slough in Mountain View, Seal Slough in San Mateo and Belmont Slough.

For cover, Ridgway's rail seeks out emergent wetland dominated by pickleweed and cordgrass, or brackish emergent wetland with those two plants plus bulrush. It is not clear whether it requires any source of fresh water. Although not migratory in coastal wetlands, this species disperses juveniles into freshwater wetlands in late August through October. Ridgway's rail has been observed to forage in or near relatively disturbed areas, leading one to deduce the importance of protecting even numeral marsh areas; for example this species was seen foraging in a small mudflat area within Seal Slough in San Mateo, three miles from the nearest known breeding area in Belmont. [7]


Ridgway's rail breeds (California rail subspecies) in the San Francisco Bay from mid-March through August, with peak activity in late June. During this breeding season the bird density was approximately 0.1 to 0.6 individuals per acre; outside of breeding season densities decline to 0.04 to 0.40 individuals per acre. [8] The twig nest is placed low, sometimes among plant roots, and purple-spotted buff eggs are laid. Eggs are produced in clutches of four to fourteen, with an average yield of 7.6. The incubation period is 18 to 29 days, and the hatching success is 38%, notably less than the similar light-footed rail indigenous to southern California.


Related Research Articles

Clapper rail New world bird of salt marshes, recently split into different species

The clapper rail is a member of the rail family, Rallidae. The taxonomy for this species is confusing and still being determined. The Ridgway's rail and the mangrove rail have been recently split. Furthermore, some taxonomists consider that the King rail and Aztec rail should be considered within this group, as those birds look similar and the birds are known to interbreed where they share territories.

Benicia State Recreation Area

Benicia State Recreation Area is a state park unit of California, United States, protecting tidal wetland. It is located in the Solano County city of Benicia, 2 miles (3.2 km) west of downtown Benicia and borders Vallejo's Glen Cove neighborhood. The park covers 447 acres (181 ha) of marsh, grassy hillsides and rocky beaches along the narrowest portion of the Carquinez Strait. Southampton Creek and the tidal marsh front Southampton Bay, where the combined waters of the Sacramento and San Joaquin Rivers approach San Pablo Bay, the northern portion of San Francisco Bay.

Don Edwards San Francisco Bay National Wildlife Refuge

Don Edwards San Francisco Bay National Wildlife Refuge (DESFBNWR) is a United States National Wildlife Refuge located in the southern part of San Francisco Bay, California. The Refuge headquarters and visitor center is located in the Baylands district of Fremont, next to Coyote Hills Regional Park, in Alameda County. The visitor center is on Marshlands Rd, off Thornton Ave.

Bair Island

Bair Island is a marsh area in Redwood City, California, covering 3,000 acres (1,200 ha), and includes three islands: Inner, Middle and Outer islands. Bair Island is part of the larger Don Edwards San Francisco Bay National Wildlife Refuge. It is surrounded by the Steinberger slough to the northwest and Redwood Creek to the southeast.

Suisun Marsh Largest brackish water marsh on west coast of US

Located in northern California the Suisun Marsh has been referred to as the largest brackish water marsh on west coast of the United States of America. The marsh land is part of the San Francisco Bay tidal estuary, and subject to tidal ebb and flood. The marsh is home to many species of birds and other wildlife, and is formed by the confluence of the Sacramento and San Joaquin rivers between Martinez and Suisun City, California and several other smaller, local watersheds. Adjacent to Suisun Bay, the marsh is immediately west of the legally defined Sacramento-San Joaquin Delta as well as part of the San Francisco Bay estuary.

<i>Rallus</i> Genus of birds

Rallus is a genus of wetland birds of the rail family. Sometimes, the genera Lewinia and Gallirallus are included in it. Six of the species are found in the Americas, and the three species found in Eurasia, Africa and Madagascar are very closely related to each other, suggesting they are descended from a single invasion of a New World ancestor.

Seal Slough

Seal Slough is a narrow winding tidal channel through a tidal marsh in San Mateo and Foster City, California. This slough has been the object of a wetland restoration project in recent years to enhance habitat value. Dredging has been carried out in Seal Slough since at least 1954. When the original sewage treatment plant for the city of San Mateo was constructed in 1935, its discharge was directed to Seal Slough.

Westpoint Slough is the largest of several sloughs feeding into Redwood Creek in San Mateo County, California, United States. This slough is surrounded by extensive undisturbed marshlands including Greco Island, which forms its northern boundary. The channel of Westpoint Slough contains considerable mudflat areas; moreover, both the marshes and mudflats offer considerable habitat area for local and migratory wildlife, especially birds.

Seal Beach National Wildlife Refuge

The Seal Beach National Wildlife Refuge is a wildlife refuge encompassing 965 acres (3.91 km2) located in the California coastal community of Seal Beach. Although it is located in Orange County it is included as part of the San Diego National Wildlife Refuge Complex. It was established in 1972.

Damon Marsh

The Damon Marsh is a tidal wetland at the northern edge of San Leandro Bay in Oakland, California, USA. There is a paved 0.84-mile (1.35 km) long shoreline trail along the waterfront to allow visual access to the San Leandro Bay and through the marsh itself. One end of this trailhead lies at Damon Slough. Access to the marsh is via the Hegenberger Road exit of Interstate 880. A 1989 biological study of the Damon Marsh found that this habitat supports the California clapper rail, a federally and state-listed endangered avian species.

Meeker Slough is a slough in Richmond, California, formed by a creek of the same name and drains into the Richmond Inner Harbor, part of San Francisco Bay. The area lies between modern tract housing in the Marina Bay neighborhood and the University of California, Berkeley Richmond Field Station's portion of Western Stege Marsh, which has been cleaned of legacy industrial contamination and restored to a productive tidal salt marsh home to the endangered California Ridgway's rail. The slough is across from Stege Marsh from which Baxter Creek drains across from a small bay they both form known as Campus Bay. The site is currently undergoing wetlands restoration.

Bill Williams River National Wildlife Refuge

The Bill Williams River National Wildlife Refuge protects the lower course of the Bill Williams River, to its mouth at Lake Havasu reservoir, in western Arizona. It is located within eastern La Paz and Mohave Counties, in the Lower Colorado River Valley region.

Tijuana Slough National Wildlife Refuge

Tijuana Slough National Wildlife Refuge is located in the most southwestern corner of the contiguous United States. As a National Wildlife Refuge, it is administered by the U.S. Fish and Wildlife Service. It was established in 1980.

Rush Creek is a stream in eastern Marin County, California, United States. It originates on the north edge of Novato, California and flows 1.5 miles (2.4 km) northeasterly through wetlands into Black John Slough and then the Petaluma River. The name is associated with Peter Rush who bought land near Novato in 1862.

The San Diego National Wildlife Refuge Complex is a series of wildlife refuges established by the United States National Wildlife Service beginning in 1972. The complex incorporates five refuges in San Diego County and Orange County in California.

Mangrove rail Species of bird

The mangrove rail is a species of bird in the family Rallidae. It is found in Central and South America. It was formerly considered conspecific with the clapper rail.

Aztec rail Species of bird

The Aztec rail or Mexican rail, is a species of bird in the family Rallidae. It is endemic to highland freshwater marshes in Mexico. The species was formerly considered a subspecies of the King rail, but further analyses have discovered it was more closely related to Ridgway's rail.

Kendall-Frost Mission Bay Marsh Reserve

The Kendall-Frost Mission Bay Marsh Reserve is a 20-acre University of California Natural Reserve System reserve on the northern shore of Mission Bay in San Diego County, California. Administered by UC San Diego, the site is owned by the University of California and managed for teaching and research.

Greco Island

Greco Island is a wetland island in Redwood City, California. Greco Island is part of the larger Don Edwards San Francisco Bay National Wildlife Refuge. Westpoint Slough follows the South side of the island while Redwood Creek is along the West. The San Francisco Bay bounds the North and East sides of the island.

Hooks Island Island in San Francisco Bay, California

Hooks Island is an approximately 36-acre (15 ha) tidal salt marsh island in the San Francisco Bay, in the city of Palo Alto, California, United States. It is home to members of several endangered species, as well as five transmission towers. It is described in a 2020 Santa Clara Valley Water report as an "undisturbed tidal salt marsh" consisting partly of an "estuarine intertidal emergent wetland". Its northern tip, located at 37°27′30″N122°05′49″W, is known as Hooks Point. Hooks Island is located directly east of the Palo Alto Baylands Sailing Station.


  1. BirdLife International (2016). "Rallus obsoletus". IUCN Red List of Threatened Species . 2016. Retrieved 15 September 2020.
  2. Chesser, R. Terry; Banks, Richard C.; Cicero, Carla; Dunn, Jon L.; Kratter, Andrew W.; Lovette, Irby J.; Navarro-Sigüenza, Adolfo G.; Rasmussen, Pamela C.; Remsen, J. V.; Rising, James D.; Stotz, Douglas F.; Winker, Kevin (October 2014). "Fifty-Fifth Supplement to the American Ornithologists' Union". The Auk. 131 (4): CSi–CSxv. doi:10.1642/AUK-14-124.1. S2CID   198151282.
  3. David C. Zeiner, William F. Laudenslayer and Kenneth E. Meyer, California’s Wildlife Volume II Birds, State of California Department of Fish and Game (990)
  4. R.L. Zembal and B.W. Massey, The light-footed clapper rail, distribution, nesting strategies and management, Cal-Neva Wildl. Manage. 36:631–634 (1983)
  5. L. Liu et al., "California Clapper Rail (Rallus longirostris obsoletus) Population monitoring: 2005–2011" PRBO Technical Report to the California Department of Fish and Game. (2012)
  6. John Kemper, Birding in California Globe Pequot Press (2001) ISBN   1-56044-832-6
  7. T.E. Harvey, H.S. Goosehead, C.M.Hogan, K.Wilson, G.W.Ball, V. Strifle et al., Section 7 endangered species biological assessment for the proposed East Third Avenue widening project, city of San Mateo, San Mateo County , prepared by Earth Metrics Inc. for the city of San Mateo, California (1980)
  8. R. E. Gill Jr., The breeding birds of south San Francisco Bay estuary, master's thesis, San Jose State University, San Jose, Ca. (1973)
  9. US-FWS: Species Profile for California Clapper rail (Rallus longirostris obsoletus)
  10. Seaworld.org: Light-Footed Clapper Rail (Rallus longirostris levipes)
  11. US-FWS: Species Profile for Yuma Clapper rail (Rallus longirostris yumanensis) . accessed 6.4.2014
  12. BLM: Yuma Clapper Rai (Rallus longirostris yumanensis)