Adults have short yellow legs and a medium thin dark bill with a yellow base. The body is dark on top with a slight purplish gloss and mainly white underneath. The breast is smeared with grey and the rump is black. They are late migrants and move to rocky ice-free Atlantic coasts in winter. most go no further south than North Carolina and northern Portugal. They are fairly gregarious, forming small flocks, often with ruddy turnstones. This species is tame and approachable. These birds forage on rocky coasts, picking up food by sight. They mainly eat arthropods and molluscs, also some plant material.