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Ridgway's Rail

Rallus obsoletus

Order:
Gruiformes
Family:
Rallidae
Sections
  • Version: 2.1 — Published March 21, 2018
  • William R. Eddleman and Courtney J. Conway
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Figure 1. Distribution of Ridgway's Rail in North America.
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Ridgway's Rail (subspecies obsoletus).

Large, gray-brown to dull cinnamon rail with slender, slightly decurved bill. Body laterally compressed, and legs and toes long relative to body size. Adult coloration highly variable, ranging from grayish brown to cinnamon brown. Back-feathers have blackish or dusky centers of varying width. Flanks marked with alternate white and dusky to dull black bars. Age unknown (probably Definitive based on plumage brightness); distinguishing Formative from Definitive Basic Plumages difficult without examining wing feathers.

© Garrett Lau, California, United States, 4 September 2017

A large cinnamon-brown rail of tidal wetlands along the Pacific Coast from northern California (San Francisco Bay area) and Baja California south to and central Mexico (Colima), as well as freshwater wetlands in the extreme southwestern United States and northwestern Mexico. Long considered by many ornithologists as a subspecies of the Clapper Rail (Rallus crepitans), phylogenetic analyses have revealed that Ridgway's Rail (R. obsoletus) is more closely related to the Aztec Rail (R. tenuirostris) of central Mexico. Up to six subspecies of the Ridgway's Rail are recognized and these breed in a range of different wetland habitats. For example, California Ridgway's Rail (R. o. obsoletus) and Light-footed Ridgway's Rail (R. o. levipes) occupy coastal saltmarshes of California and northwestern Baja California; Yuma Ridgway's Rail (R. o. yumanensis) occurs in freshwater, brackish, and salt marshes from southeastern California and southwestern Arizona south to northwestern Sonora; and R. o. nayaritensis breeds in coastal saltmarshes and mangroves in western Mexico from central Sinaloa to southern Nayarit.

Ridgway's Rail typically feeds on crustaceans, but take a variety of other invertebrate prey, fish and other small vertebrates, and seeds. Males average larger in size and mass than females, but sexes are similar in plumage. Both sexes assist in incubation and brood-rearing. The species is sedentary, but may undergo postbreeding dispersal, as indicated by radio-telemetry studies and by occasional inland records away from breeding habitats.

Within the U.S., Ridgway's Rail is represented by three subspecies: obsoletus, levipes, and yumanensis. These subspecies have limited habitat availability, and consequently face threats from habitat loss, pollutants, urbanization, and non-native predators; all three subspecies are classified as endangered by the U.S. Fish and Wildlife Service. Although the species' endangered status has lead to much research on obsoletus, levipes, and yumanensis in the western U.S., there are many aspects of Ridgway's Rail biology that remain poorly understood. Research needs include (1) continued population monitoring to assess distribution, relative abundance, and population size and trends, (2) studies of movement ecology, (3) the effects of habitat management, (4) the effects of sea-level rise and other disturbances, (5) the effects of environmental contaminants on reproduction and survival, (6) taxonomic status of other subspecies, and their distribution and natural history, and (7) investigations of basic biology, with emphasis on population parameters, calling behavior, postbreeding biology, and wintering biology.

Recommended Citation

Eddleman, W. R. and C. J. Conway (2018). Ridgway's Rail (Rallus obsoletus), version 2.1. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.ridrai1.02.1