Systematics

Body size varies geographically; largest along Pacific coast, intermediate along Gulf and Atlantic coasts, and smallest in Caribbean (see Appendix 1). Plumage and soft-part colors also vary; West Indies birds slightly darker than those of Atlantic, Gulf, and Caribbean coasts.

Six subspecies recognized (Wetmore 1945), now divided into 2 groups sometimes considered separate species (Am. Ornithol. Union 1998). Subspecies distinguished on basis of body size and color of plumage and soft parts. Hindneck color during breeding season, once used as a criterion for assigning subspecies (Wetmore 1945), shown to be highly variable within and among subspecies (Schreiber et al. 1989). Distributional limits of subspecies poorly known, especially in Middle America and n. South America.

Brown Pelican (Occidentalis Group).

Five subspecies breeding from s. U.S. south to coastal nw. South America (to Ecuador), Galápagos Is., and n. South America (to Venezuela and Trinidad and Tobago).

P. o. occidentalis Linnaeus, 1766. Breeds s. Bahamas, Greater and Lesser Antilles, and along Caribbean coast of Colombia and Venezuela to Trinidad and Tobago (Am. Ornithol. Union 1957, van Halewyn and Norton 1984). Ranges throughout West Indies; wanders to Gulf coast of Florida, Caribbean coast of Mexico (Wetmore 1945), and as far as ne. Brazil (Blake 1977). Recognizable by small size (smallest of the subspecies; see Appendix 1) and darker undersurface (Wetmore 1945).

P. o. carolinensis Gmelin, 1789. Breeds along Atlantic, Gulf, and Caribbean coasts from Maryland south around Florida and west to s. Texas, s. Veracruz, Yucatán Peninsula, Belize, and Honduras; also breeds on Pacific coast of Honduras, Costa Rica, and Panama (Am. Ornithol. Union 1957, 1998; Blake 1977). Ranges throughout Atlantic, Gulf, and Caribbean coastal and insular areas from s. New York (casually north to New England and Nova Scotia) south to e. Venezuela (rarely to Brazil) and along Pacific coast from s. Mexico (1 record from central Pacific coast of Mexico; D. Blankinship pers. comm.) to n. Peru, and inland to great lakes of Nicaragua (Murphy 1936; Am. Ornithol. Union 1957, 1998). Distinguished from P. o. occidentalis by larger size and lighter undersurface (Wetmore 1945).

P. o. californicus Ridgway, 1884. Breeds from California Channel Is. south along Pacific coast of Baja California, throughout Gulf of California (south of northernmost portion, however), and south along Pacific coast of Mexico to Islas Tres Marias (Am. Ornithol. Union 1957, 1998). Also recently breeding inland at Salton Sea (Sturm 1998). Ranges from s. British Columbia south along Pacific coast to Colima, Mexico (rarely to El Salvador), and inland to s. California and Arizona, casually elsewhere in interior of sw. U.S. (Am. Ornithol. Union 1957, U.S. Fish Wildl. Serv. 1983). One record from Gulf coast of Mexico (D. Anderson pers. comm.). Distinguished from P. o. occidentalis and P. o. carolinensis by larger size and red, rather than blackish metallic green, on proximal end of gular pouch during courtship (Schreiber et al. 1989).

P. o. urinator Wetmore, 1945. Resident in Galápagos Is. Similar to P. o. californicus, but darker above and usually below (Wetmore 1945) and lacks red on gular pouch (Rothschild and Hartert 1899).

P. o. murphyi Wetmore, 1945. Known to breed only on Isla Santa Clara in Gulf of Guayaquil, Ecuador (Ridgely and Greenfield 2001). Ranges along Pacific coast of Colombia and Ecuador, south to Talara, Peru (Wetmore 1945). Similar in size to P. o. carolinensis, the subspecies to which birds from this region were formerly assigned, but darker above and more extensively streaked with light below (Wetmore 1945).

Peruvian Pelican (Thagus Group).

Pacific coast of South America from s. Ecuador to s. Chile. Larger, entire underparts finely streaked white (each feather with narrow shaft-stripe), gular pouch more brightly colored (and blue) during breeding season, and caruncles on bare skin at base of culmen.

P. o. thagus Molina, 1782. Endemic to Peruvian Coastal (Humboldt) Current System. Breeds along Pacific coast from n. Peru to central Chile; ranges north to s. Ecuador, south to s. Chile (Wetmore 1945, Am. Ornithol. Union 1998). Distinguished from occidentalis group by larger size, caruncles on bare skin between base of culmen and eyes, horny papillae on base of culmen and around base of lower mandible below gape, larger occipital crest, completely streaked undersurface (Wetmore 1945), yellow rather than white lateral neck-stripe acquired just prior to onset of breeding (Forbes 1914), blue gular pouch during breeding season, and 2 pairs of white patches formed by upper wing-coverts (one over primaries and secondaries, other over tertiaries; Schreiber et al. 1989).

All pelicans are placed in the same genus, but Brown Pelican seems not to be particularly close to other species (dark plumage, marine habitat, and plunge-diving behavior). Pelicans are a traditional member of order Pelecaniformes, having totipalmate foot and distensible gular pouch. Close relationship of pelicans and the Shoebill (Balaeniceps rex), suggested in past based on morphology (e.g., Cottam 1957, Olson 1979), has been inferred from DNA hybridization (Sibley and Ahlquist 1990) and DNA sequence evidence (Hedges and Sibley 1994). Also see Cracraft 1985 and Siegel-Causey 1997 for other proposed relationships among Pelecaniformes.