The Ruddy Turnstone (Arenaria interpres) is a small wading bird, one of two species of turnstone in the genus Arenaria. It is now classified in the sandpiper family Scolopacidae but was formerly sometimes placed in the plover family Charadriidae. It is a highly migratory bird, breeding in northern parts of Eurasia and North America and flying south to winter on coastlines almost worldwide. It is the only species of turnstone in much of its range and is often known simply as Turnstone.
It is a fairly small and stocky bird, 22–24 centimetres (8.7–9.4 in) long with a wingspan of 50–57 centimetres (20–22 in) and a weight of 85–150 g (3.0–5.3 oz). The dark, wedge-shaped bill is 2–2.5 centimetres (0.79–0.98 in) long and slightly upturned. The legs are fairly short at 3.5 centimetres (1.4 in) and are bright orange.
At all seasons, the plumage is dominated by a harlequin-like pattern of black and white. Breeding birds have reddish-brown upper parts with black markings. The head is mainly white with black streaks on the crown and a black pattern on the face. The breast is mainly black apart from a white patch on the sides. The rest of the underparts are white. In flight it reveals a white wingbar, white patch near the base of the wing and white lower back, rump and tail with dark bands on the uppertail-coverts and near the tip of the tail. The female is slightly duller than the male and has a browner head with more streaking.
Non-breeding adults are duller than breeding birds and have dark grey-brown upperparts with black mottling and a dark head with little white. Juvenile birds have a pale brown head and pale fringes to the upperpart feathers creating a scaly impression.
In the Danube Delta we find them during the migration period, spring and autumn, especially along the Black Sea coast.