Ruddy turnstone but it feeds mainly on invertebrates. Insects are particularly important in the breeding season. At other times it also takes crustaceans, molluscs and worms. It often flips over stones and other objects to get at prey items hiding underneath; this behaviour is the origin of the name "turnstone". It usually forages in flocks. They have also been observed preying on the eggs of other bird species such as gulls, terns, ducks, and even other turnstones, though this behaviour is uncommon. In the majority of observed cases, turnstones typically go after undefended or unattended nests, puncturing the shells with their beaks
Black turnstone and breast become largely dark brown with little white. Juveniles are similar to winter adults but browner with buff fringes to the wing-coverts and scapulars and a grey-brown tip to the tail. The ruddy turnstone is similar but has rufous-brown markings on the upperparts and more white on the head and breast, particularly in breeding plumage. It has narrower wings and a narrower white wingbar. Its legs are orange and brighter than those of the black turnstone though there can be some overlap. The black turnstone has a variety of calls, especially a rattling trill which can be heard throughout