Rallus obsoletus obsoletus
Ridgway, 1874
California Ridgway's Rail
T1T1Global Rank
LEESA Status
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.1010073
Element CodeABNME05011
Record TypeSPECIES
ClassificationSubspecies
Classification StatusStandard
Name CategoryVertebrate Animal
Endemicendemic to a single state or province
KingdomAnimalia
PhylumCraniata
ClassAves
OrderGruiformes
FamilyRallidae
GenusRallus
USESALE
Synonyms
Rallus longirostris obsoletusRidgway, 1874
Concept Reference
Lepage, D., G. Vaidya, and R. Guralnick. 2014. Avibase - a database system for managing and organizing taxonomic concepts. Zookeys 420:117-135. [As modified by subsequent updates at: https://avibase.bsc-eoc.org/].
Conservation Status
Rank MethodLegacy Rank calculation - Excel v3.1x
Review Date2017-08-29
Change Date2017-08-29
Edition Date2017-08-29
Range Extent<100-250 square km (less than about 40-100 square miles)
Number of Occurrences1 - 5
Rank Reasons
Small range in the San Francisco Bay Area, California; extirpated from other sites in northern and central California; population has declined greatly compared to historical abundance, now consists of several hundred individuals; decline was due primarily to loss of marsh habitat; predation by introduced red has been a recent problem, though fox control has alleviated this threat and allowed population to increase.
Range Extent Comments
This species is confined to central California. It was historically known from Francisco Bay and, formerly, Humboldt Bay (Humbolt County), Morro Bay (San Luis Obispo County), and Elkhorn Slough (Monterey County), California. It is now restricted to San Francisco Bay ecosystem: Dumbarton Point, Mowry Slough, and Arrowhead Marsh in Alameda County, Palo Alto Baylands in Santa Clara County, the Faber Tract, Greco Island, and Bair Island in San Mateo County, and Corte Madera Marsh Ecological Reserve, Muzzi Marsh, and Gallinas Creek in Marin County. During the spring breeding season smaller numbers occur in Suisun Bay marshes, Napa Marsh, and the southern end of South San Francisco Bay (California Department of Fish and Game 1990). About 90% of the population occurs in the south bay region.
Threat Impact Comments
Initial decline was due to hunting, followed by loss and degradation on tidal marsh habitat. About 80% of the original habitat has been diked or destroyed. Threatened today by pollution from sewage effluent, industrial discharges, and urban runoff, which may be contaminating food resources. Sewage effluent in south bay has changed salt marsh to less valuable brackish marsh (California Department of Fish and Game 1990). Marsh erosion, as yet not fully understood, may become a problem. Introduced red fox spread around south bay in the 1980s and is thought to be responsible for recent drastic declines in San Francisco Bay National Wildlife Refuge (California Department of Fish and Game 1990, Albertson et al. 1992). Control of foxes and feral cats in the early 1990s corresponded with an apparent population increase in the mid-1990s.
Ecology & Habitat
Habitat
Pickleweed (Salicornia) and cordgrass (Spartina foliosa) marshes high marsh is needed during winter flood tides (Eddleman et al. 1988). Nests in marshlands (cordgrass, pickleweed, gum-plant, salt grass) near tidal ponds, arranging plants or drift material over the nest as a canopy. Often constructs brood nest on higher ground to shelter young from storm tides. In South San Francisco Bay, prefers to nest in stands of cordgrass but builds nest mostly of pickleweed (Matthews and Moseley 1990).
Reproduction
Nesting occurs mid-March to July, with peaks in early May and again in early July (Matthews and Moseley 1990).
Other Nations (1)
United StatesN1
| Province | Rank | Native |
|---|---|---|
| California | S2 | Yes |
Roadless Areas (7)
California (7)
| Area | Forest | Acres |
|---|---|---|
| Big Rocks | Los Padres National Forest | 11,866 |
| Black Mountain | Los Padres National Forest | 16,818 |
| Garcia Mountain | Los Padres National Forest | 7,850 |
| La Panza | Los Padres National Forest | 4,954 |
| Los Machos Hills | Los Padres National Forest | 11,112 |
| Machesna Mountain | Los Padres National Forest | 12,271 |
| Stanley Mountain | Los Padres National Forest | 14,674 |
References (7)
- Albertson, J. D., J. E. Takekawa, and T. B. Smith. 1992. Implications of predation on the endangered California clapper rail in south San Francisco Bay. Abstract, Society for Conservation Biology, 6th Annual Meeting, p. 31.
- California Department of Fish and Game (CDF&G). 1990. 1989 annual report on the status of California's state listed threatened and endangered plants and animals. 188 pp.
- Eddleman, W. R., F. L. Knopf, B. Meanley, F. A. Reid, and R. Zembal. 1988. Conservation of North American rallids. Wilson Bulletin 100:458-475.
- Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1992. Birds in Jeopardy: the Imperiled and Extinct Birds of the United States and Canada, Including Hawaii and Puerto Rico. Stanford University Press, Stanford, California. 259 pp.
- Lepage, D., G. Vaidya, and R. Guralnick. 2014. Avibase - a database system for managing and organizing taxonomic concepts. Zookeys 420:117-135. [As modified by subsequent updates at: https://avibase.bsc-eoc.org/].
- Matthews, J.R. and C.J. Moseley (eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants, Mammals. xxiii + pp 1-560 + 33 pp. appendix + 6 pp. glossary + 16 pp. index. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Arachnids. xiii + pp. 561-1180. Beacham Publications, Inc., Washington, D.C.
- U.S. Fish and Wildlife Service (USFWS). 1990. Endangered and threatened species recovery program: report to Congress. 406 pp.