The Ruddy Turnstone, Arenaria interpres, also often simply referred to as Turnstone, is a small, migratory wading bird.

It is a fairly small bird, around 22–24 cm (8.7–9.4 in) long and with a wingspan of 50–57 cm (20–22 in). The dark, wedge-shaped bill is slightly upturned. The legs are shortish at 3.5 cm (1.4 in) and are bright orange.

Plumage is predominantly black and white, although 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 and the underparts are white. The female is slightly duller than the male and has a browner head with more streaking.

The Ruddy Turnstone has a very varied diet including eggs, fish, plants, insects and larvae (in the breeding season) as well as being partial to the occasional crustacean, spider, mollusc or even the odd worm.