Systematics

Individuals from northernmost and westernmost populations are larger in all measurements except culmen length, which is shortest in West Coast and southernmost forms. Bill heaviest in South American birds and most slender in birds of e. North America and the Caribbean (Olson 1997). Overall body coloration of individuals from East Coast of U.S. and Caribbean populations gray to dull gray brown or buff; northern subspecies grayer (Oberholser 1937, Ripley 1977). Birds from West Coast of U.S. and freshwater habitats buff to rich cinnamon. Individuals darker and more richly colored from north to south along coasts of e. U.S., w. Mexico, and Baja California (Ripley 1977). Most populations from East Coast of Mexico and Central America and n. Caribbean paler than mainland coastal forms (Ripley 1977). Different color morphs may complicate plumage description of subspecies. Populations from Arizona south to Nayarit, Mexico, show cline of decreasing wing length and slightly darker dorsal coloration (Ripley 1977). See Appearance, and Measurements: linear, below.

For the King and Clapper rail as a whole (elegans-longirostris complex), between 20 (Peters 1934) and 27 (Ridgway and Friedmann 1941) subspecies are recognized. This account includes the subspecies in Ripley (1977), excluding the 3 subspecies currently included under King Rail (elegans, ramsdeni of inland Cuba, and tenuirostris of central Mexico).

Subspecies are distinguished mainly by differences in coloration of underparts and upperparts, wing length, culmen length, and overall body size. May be considerable overlap in plumage color and measurements where distributions of subspecies overlap (Heard 1983). Three groups of subspecies distinguished: obsoletus group of West Coast of North America, crepitans group of e. North America, Caribbean, and Yucatán; and longirostris group of South America. All resident, except where noted.

Obsoletus Group.

Four subspecies in obsoletus group distinguished largely by buff to cinnamon brown underparts and more richly colored plumage. Cheeks generally brownish. Subspecies in this group have also been considered separate species (Bent 1926) or subspecies of elegans (Peters 1934, Hellmayr and Conover 1942, Olson 1997).

R. l. obsoletus Ridgway, 1874. San Francisco Bay, CA, area (and formerly in Tomales and Monterey Bays). Largest subspecies; throat, breast, and upper abdomen ochraceous buff; flanks dark sepia to black, contrasting with white barring; cheeks brownish.

R. l. levipes Bangs, 1899. Santa Barbara, CA, to San Quintín Bay, Baja California Sur. Averages slightly smaller than obsoletus; breast deep cinnamon rufous; flanks and back darker in comparison to obsoletus .

R. l. yumanensis Dickey, 1923. Lower Colorado River (Arizona and California), Colorado River delta (Sonora and Baja California Norte), and West Coast of Mexico from Punta Sargento, Sonora, to San Blas, Nayarit. Distinguished by paler, duller underparts and grayish edging of dorsal feathers. Cheeks and postoculars bluish or ashy gray. Ripley (1977) considered rhizophorae Dickey, 1930 (Punta Sargento, Sonora, to central Sinaloa) and nayaritensis McLellan, 1927 (central Sinaloa to San Blas, Nayarit) as clinal variations of yumanensis . Additional specimens might confirm the validity of these subspecies (but see Banks and Tomlinson 1974).

R. l. beldingi Ridgway, 1882. Mangrove swamps from Margarita Bay on Pacific Coast to Espíritu Santo I. on Gulf Coast of Baja California Sur (includes magdalenae van Rossem, 1947).

Crepitans Group.

Twelve subspecies in crepitans group have grayish to dull cinnamon underparts and long, slender bill. Feathers of upperparts edged in various shades of gray, and cheeks grayish.

R. l. crepitans Gmelin, 1789. Breeds from s. New England to se. North Carolina; winters from breeding range to ne. Florida. Migratory, large, grayish subspecies. Underparts pale cinnamon buff; culmen long. Winters from breeding range to ne. Florida.

R. l. waynei Brewster, 1899. Se. North Carolina, where it intergrades with crepitans, to Volusia and Brevard Cos. in ne. Florida, where it intergrades with scotti in Indian River, Saint Lucie, and Martin Cos. (Stevenson and Anderson 1994). Resembles crepitans, but is slightly smaller and darker on upperparts. Underparts more cinnamomeous, with an ashy band across upper breast.

R. l. scottii Sennett, 1888. Jupiter Inlet, Martin Co., FL; around southern tip of Florida to Pensacola, Escambia Co., FL, intergrading with saturatus (see below) in w. Florida Panhandle. It has the darkest upperparts of all subspecies: blackish brown, shaded with grayish olive. Breast cinnamon, shaded with olive brown.

R. l. insularum Brooks, 1920. Florida Keys from Key Largo to Boca Grande and, presumably, Marquesas Keys (Owre 1978). Similar to waynei (see above), but smaller; culmen shorter; feathers of upperparts more broadly edged with grayish. Overall coloration relatively pale.

R. l. saturatus, Ridgway 1880. Gulf Coast from Florida Panhandle to Tamaulipas, Mexico. More brownish than other subspecies of eastern U.S. Closely resembles King Rail, except duller and less rufescent on underparts; grayish edging on feathers of upperparts.

This group also includes pallidus Nelson, 1905 (Río Lagartos, Yucatan); grossi Paynter, 1950 (islands on Chinchorro Reef, Quintana Roo, Mexico); belizensis Oberholser, 1937 (Ycacos Lagoon, Belize, and possibly Half Moon Cay, Belize); coryi Anonymous = Maynard, 1887 (Bahama Is.); leucophaeus Todd, 1913 (Isle of Pines, Cuba); caribaeus Ridgway, 1880 (n. Antilles, islands of Cuba, Hispaniola, Puerto Rico, to Antigua and Guadeloupe—includes cubanus Chapman, 1892; vafer Wetmore, 1928; limnetis Oberholser, 1937; manglecola Danforth, 1914; Ripley 1977); and pelodramus Oberholser, 1937 (Trinidad).

Longirostris Group.

Characterized by relatively small body size and short, heavy bill. Consists of 5 subspecies from South America: margaritae Zimmer and Phelps, 1944 (Margarita I., Venezuela); phelpsi Wetmore, 1941 (northern coast of Colombia and Venezuela); longirostris Boddaert, 1789 (coasts of Guyana, Suriname, and French Guiana); crassirostris Lawrence, 1871 (coastal salt marshes of e. Brazil); and cypereti Taczanowsky, 1877 (Ecuador and nw. Peru).

Very little divergence in mitochondrial DNA among subspecies yumanensis, levipes, obsoletus, crepitans, and saturatus (Fleischer et al. 1995). Subspecies yumanensis and levipes probably had common ancestor within last 50,000 yr, but minisatellite and Randomly Amplified Polymorphic (RAPD) DNA differences suggest there has been little genetic interchange recently.

Hybridizes with King Rail in brackish marshes where geographic ranges overlap (Meanley and Wetherbee 1962, Meanley 1969, Bledsoe 1988). Hybrids show variety of plumage intergradations (Meanley 1969), and may partly explain “color phases” of Clapper Rails. Accordingly, many taxonomists consider Clapper Rail and King Rail conspecific (Ripley 1977). Mitochrondrial DNA studies of Clapper and King rails are inconclusive regarding their specific status (Avise and Zink 1988). Wetmore’s Rail similar in appearance and habitat, but considered separate species because of geographical overlap with Clapper Rail in n. South America (Ripley 1977). Clapper, King, and Wetmore’s rails presently are construed as a superspecies group (Sibley and Monroe 1991).