The Ruddy Turnstone, a small, robust, Holarctic shorebird, is 1 of 2 species that make up the genus Arenaria and 1 of the most northerly breeding species of shorebirds. Although well known from its migratory movements and winter distributions on southern seacoasts throughout the world, its summer activities on the breeding grounds have only recently received attention and remain poorly known, particularly in northern parts of its range. In North America, its breeding biology remains largely unstudied. It breeds in tundra regions of northern North America from Alaska to Greenland (Figure 1). High-arctic Canadian and Greenland birds winter mainly along coastal shores in Britain and Ireland and south along the Atlantic coast of southwestern Europe (Iberian Peninsula) and northwestern Africa (some farther south); those breeding south and west of north Devon Island, Nunavut, winter mostly in northern Brazil, but also along both coasts of North and Central America from Long Island (New York) and coastal Gulf of Mexico and central California south through the West Indies and along coastal South America to Tierra del Fuego (Figure 1).
An opportunistic feeder, the Ruddy Turnstone feeds on rocky and sandy beaches during winter and on migration, by turning over rocks, pebbles, seaweeds, shells, and other items with its stout, strong, and slightly upturned upper mandible, also used to probe, jab, and dig for food in winter and summer. Its diet when breeding is predominantly dipteran insects (flies). Outside the breeding season, foods are extremely diverse, ranging from coastal invertebrates to small fish, carrion, human garbage, and unattended eggs of other avian species.
The North American population size is roughly 267,000 breeding birds (about 59% of the global total), mainly in arctic Canada, with fewer numbers in Greenland. Ruddy Turnstones reach the breeding grounds in late May or early Jun, earlier in Alaska. Monogamous and territorial, they display high site and mate fidelity, and occupy dry, open tundra flats and slopes near ponds, lakes, and streams, usually laying a 4-egg clutch in mid-Jun. Incubation averages 22 days, mostly by the female, with the male serving as sentinel-guard to detect predators. Eggs hatch early to mid-Jul, rapidly and synchronously, with family groups deserting the nest within 24 hours after the last egg hatches. Both parents attend young, female departing before male, with most chicks fledging late Jul and early Aug and becoming independent of parents. Most adults depart breeding grounds before mid-August; remaining adults always males. Fledglings usually depart in mid-August, with annual breeding cycle complete before mid-Sep. Both high- and low-arctic populations show site fidelity to winter quarters.
Important references on Ruddy Turnstone are few. Key papers for breeding biology and behavior include Paget-Wilkes 1922; Bent 1929; Bergman 1946; Nordberg 1950; Bianki 1967; Nettleship Nettleship 1967, Nettleship 1973a; Stout et al. 1967; Vuolanto 1968; Beven and England 1977; Väisänen 1977; Whitfield 1986; and Piersma and Morrison 1994 . Those for migration are Bent 1927; Thompson 1973c; Morrison Morrison 1975, Morrison 1984c; Wilson 1981; Summers et al. 1989; Alerstam et al. 1990; and Gudmundsson et al. 1991 . For aspects of winter ecology, important sources include Baker Baker 1971a, Baker 1977c; Jones 1975a; Glutz Von Blotzheim et al. 1977; Harris 1979c; Robertson and Dennison 1979; Fleischer 1983b; Metcalfe and Furness 1985; Metcalfe 1986; Klaassen et al. 1990; and Whitfield 1990a . The major review and bibliography on Ruddy Turnstone is Cramp and Simmons 1983, supplemented by Johnsgard 1981, Piersma et al. 1996c, and Van Gils and Wiersma 1996c .