Systematics

Type locality restricted to Gotland, Sweden, based on original description as Tringa Interpres by Linnaeus in 1758. Distinctive nature of the turnstone soon recognized with genus Arenaria proposed by Brisson (1760).

Two subspecies recognized (Am. Ornithol. Union 1957, Cramp and Simmons 1983); both occur in North America. Races differ slightly in size and coloration. Slight sexual dimorphism somewhat obscures racial differences, and subspecies most readily separated only by comparison of adult male in breeding plumage (Definitive Alternate). Because of this, winter range and migration patterns of races poorly known. Also see Ridgway 1919; Bent 1929; Bird and Bird 1941; Salomonsen 1950; Godfrey 1953, 1986; and Engelmoer and Roselaar 1998 .

A. i. interpres (Linnaeus, 1758): Circumpolar breeding range from ne. high-arctic Canada (Axel Heiberg and Ellesmere Is. in Queen Elizabeth Is.), n. and ne. Greenland, and across arctic Eurasia (including Spitsbergen, Scandinavia, Novaya Zemlya, New Siberian Is., n. Siberia) to w. and nw. Alaska (Bering and Chukchi sea coasts). Winters from w. and s. Europe south to s. Africa, India, Indonesia, Australia, New Zealand; Canadian arctic populations mainly migrate to and winter in Old World; birds from ne. Siberia and nw. Alaska probably migrate chiefly along Asiatic coast but also winter along Pacific Coast of North America south to s. Mexico (but probably also well beyond), Hawaiian Is. and throughout Pacific islands. More extensive black streaking on head, less extensive and paler russet (deep chestnut-red) on dorsum, particularly mantle; slightly longer wing and shorter bill and tarsus; separated by wing:bill and wing:tarsus ratios (>6.6 and >5.9, respectively; for details, see Table 2). Populations from n. Siberia to w. Alaska have been given name cinclus and oahuensis; although these may prove recognizable under one of these names (K. C. Parkes in Gibson and Kessel 1997), they are synonymized under nominate interpres (see Hellmayr and Conover 1948, Godfrey 1986).

A. i. morinella (Linnaeus, 1766): Breeds from ne. Alaska (Beaufort Sea coast) east through southern islands of Canadian Arctic Archipelago (south of 75°N) to sw. Queen Elizabeth Is. (Prince Patrick, Melville, Bathurst, Cornwallis, and probably most of Devon Is.) south to sw. Baffin I., and Southampton, Mansel, and Coats Is.; local breeding population in central-w. Greenland (Qeqertarsuaq/Godhavn) probably this race (Boertmann 1994). Winters mainly from s. U.S. along Atlantic and Gulf coasts south around Caribbean Sea, West Indies, and along both coasts of South America (including Netherland Antilles, Trinidad and Tobago, Galapagos Is.) south to Tierra del Fuego, with largest concentrations from Suriname to ne. Brazil and Peru. Region where morinella and nominate interpres intergrade uncertain, but perhaps Devon I. and n. Baffin I. westward (Am. Ornithol. Union 1957). Less black streaking on head and upperparts, brighter rufous to orange-rufous on dorsum; slightly shorter wing and slightly longer bill and tarsus; differences in wing:bill and wing:tarsus ratios (see nominate interpres, above).

Black Turnstone only congener. Both species make up genus Arenaria in tribe Arenariini, subfamily Scolopacinae (Am. Ornithol. Union 1998). Because the 2 species are only narrowly sympatric in w. Alaska, suggested to constitute a superspecies (Mayr and Short 1970). Turnstones formerly ranked as separate subfamily and even thought close to plovers. Also previously allied with Surfbird (Aphriza virgata), but close relationship not supported by morphological and behavioral analyses by Jehl (1968) and Chu (1995), who showed that Aphriza and Arenaria grouped with Calidris sandpipers. No conclusive biochemical studies exist. Adaptive radiation of true shorebirds, such as plovers and sandpipers, characterized primarily by variations in their feeding apparatus (Burton 1974) and associated differences in form of cranial kinesis. Turnstones exhibit distinctive adaptations in this regard.