The California Clapper Rail (Rallus longirostris obsoletus) is an endangered

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of the Clapper Rail

Clapper Rail

The Clapper Rail is a member of the rail family, Rallidae. Some researchers believe that this bird and the similar King Rail are a single species; the two birds are known to interbreed.-Distribution and habitat:...

 (R. longirostris). It is found principally in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

's San Francisco Bay

San Francisco Bay

San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...

, and also in Monterey Bay

Monterey Bay

Monterey Bay is a bay of the Pacific Ocean, along the central coast of California. The bay is south of San Francisco and San Jose, between the cities of Santa Cruz and Monterey....

 and Morro Bay. A member of the rail family, Rallidae

Rallidae

The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...

, it is a chicken-sized

Chicken

The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...

 bird that rarely flies.

Like other subspecies of Clapper Rail, this form has a long, downward curving bill and is grayish brown with a pale chestnut breast and conspicuous whitish rump patch. The population levels of the California Clapper 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 crepuscular

Crepuscular

Crepuscular animals are those that are active primarily during twilight, that is during dawn and dusk. The word is derived from the Latin word crepusculum, meaning "twilight." Crepuscular is, thus, in contrast with diurnal and nocturnal behavior. Crepuscular animals may also be active on a bright...

ly.

Habitat

The California Clapper Railer forages at the upper end of , along the ecotone

Ecotone

An ecotone is a transition area between two biomes but different patches of the landscape, such as forest and grassland. It may be narrow or wide, and it may be local or regional...

 between mudflat and higher vegetated zones, and in tidal slough

Swamp

A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...

s. Mussel

Mussel

The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...

s, clam

Clam

The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...

s, arthropod

Arthropod

An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...

s, snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s, worm

Worm

The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

s and small fish are its preferred foods, which it retrieves by probing and scavenging the surface while walking. The bird will only forage on mudflat

Mudflat

Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...

s 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.

The largest population of California Clapper Rails is in San Francisco Bay, where a total of about 3000 are resident. The photo above right was taken of a California Clapper Rail at the San Francisco Bay perimeter near the Dumbarton Bridge

Dumbarton Bridge (California)

The Dumbarton Bridge is the southernmost of the highway bridges that span the San Francisco Bay in California. Carrying over 81,000 vehicles daily, it is also the shortest bridge across San Francisco Bay at 1.63 miles...

; the Don Edwards San Francisco Bay National Wildlife Refuge

Don Edwards San Francisco Bay National Wildlife Refuge

Don Edwards San Francisco Bay National Wildlife Refuge is a US 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. ...

 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

Napa Sonoma Marsh

The Napa Sonoma Marsh is a wetland at the northern edge of San Pablo Bay, which is a northern arm of the San Francisco Bay in California, USA. This marsh has an area of 48,000 acres , of which 13,000 acres are abandoned salt evaporation ponds...

, Bothin Marsh in Mill Valley

Mill Valley, California

Mill Valley is a city in Marin County, California, United States located about north of San Francisco via the Golden Gate Bridge. The population was 13,903 at the 2010 census.Mill Valley is located on the western and northern shores of Richardson Bay...

, Gallinas Creek in San Rafael

San Rafael, California

San Rafael is a city and the county seat of Marin County, California, United States. The city is located in the North Bay region of the San Francisco Bay Area...

, Arrowhead Marsh

Arrowhead Marsh

Arrowhead Marsh is a wetlands habitat made of tidal mud flats in Martin Luther King, Jr. Shoreline in Oakland, California. It is an important stop on the Pacific flyway and is habitat for important endangered species especially the Salt Marsh Harvest Mouse....

 in Oakland

Oakland, California

Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...

, the Palo Alto

Palo Alto, California

Palo Alto is a California charter city located in the northwest corner of Santa Clara County, in the San Francisco Bay Area of California, United States. The city shares its borders with East Palo Alto, Mountain View, Los Altos, Los Altos Hills, Stanford, Portola Valley, and Menlo Park. It is...

 baylands, Charleston Slough in Mountain View

Mountain View, California

-Downtown:Mountain View has a pedestrian-friendly downtown centered on Castro Street. The downtown area consists of the seven blocks of Castro Street from the Downtown Mountain View Station transit center in the north to the intersection with El Camino Real in the south...

, Seal Slough

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...

 in San Mateo

San Mateo, California

San Mateo is a city in San Mateo County, California, United States, in the San Francisco Bay Area. With a population of approximately 100,000 , it is one of the larger suburbs on the San Francisco Peninsula, located between Burlingame to the north, Foster City to the east, Belmont to the south,...

 and Belmont Slough.

For cover the California Clapper Rail seeks out emergent wetland dominated by pickleweed

Pickleweed

Pickleweed is a common name used for two unrelated genera of flowering plants:*Batis, family Bataceae*Salicornia, family Amaranthaceae...

and cordgrass

Cordgrass

Spartina, commonly known as cordgrass or cord-grass, is a genus of 14 species of grasses in the family Poaceae. They are native to the coasts of the Atlantic Ocean in western and southern Europe, northwest and southern Africa, the Americas and the southern Atlantic Ocean islands; one or two species...

, or brackish emergent wetland with those two plants plus bulrush

Bulrush

-Wetland plants:* Bolboschoenus, a genus in the sedge family * Cyperus, a genus in the sedge family * Scirpus, a genus in the sedge family * Schoenoplectus, a genus in the sedge family...

. It is not clear whether it requires any source of fresh water. Although not migratory

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 in coastal wetland

Wetland

A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

s, this species disperses juveniles into freshwater wetlands in late August through October. The California Clapper Rail has been observed to forage

Foraging

- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...

 in or near relatively disturbed areas, leading one to deduce the importance of protecting even numeral marsh

Marsh

In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....

 areas; for example this species was seen foraging in a small mudflat area within Seal Slough

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...

 in San Mateo, three miles from the nearest known breeding area in Belmont

Belmont, California

Belmont is a city in San Mateo County, California, United States. It is in the San Francisco Bay Area, located half-way down the San Francisco Peninsula between San Mateo and San Carlos. It was originally part of the Rancho de las Pulgas, for which one of its main roads, the Alameda de las Pulgas,...

.

Breeding

The California Clapper Rail breeds in the San Francisco Bay from mid-March through July, 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. The twig nest is placed low sometimes among plant roots, and three purple-spotted buff eggs are laid. Eggs are produced in clutches of four to fourteen, with an average yield of 7.6. The incubation

Avian incubation

Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 period is 18 to 29 days, and the hatching success is 38%, notably less than the similar Light-footed Clapper Rail indigenous to southern California.

Comparison to some other subspecies

A close relative of the California Clapper Rail is the Light-footed Clapper Rail, Rallus longirostris levipes, a U.S. federal and California state listed endangered subspecies that ranges from Santa Barbara County

Santa Barbara County, California

Santa Barbara County is a county located in the southern portion of the U.S. state of California, on the Pacific coast. As of 2010 the county had a population of 423,895. The county seat is Santa Barbara and the largest city is Santa Maria.-History:...

 to the extreme north of the Mexican

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 coast of the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

.

Other races of Clapper Rail are found along the east coast of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, where populations are stable although numbers have declined due to habitat loss, the coasts and some islands of the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

, and across northern South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 to eastern Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

. The Trinidad

Trinidad

Trinidad is the larger and more populous of the two major islands and numerous landforms which make up the island nation of Trinidad and Tobago. It is the southernmost island in the Caribbean and lies just off the northeastern coast of Venezuela. With an area of it is also the fifth largest in...

ian subspecies, R. l. pelodromus, is more heavily marked with black above than any of the other Clapper Rail forms.