Seaside gulls aren’t the only birds which have learnt that chip shop chips are tasty. Turnstones normally feed in the intertidal zone. They do turn small stones over with their beaks, looking for food. Likewise with seaweed.
They can often be spotted when the tide is out in estuaries and harbours. One denizen of Brixham harbour some years ago had swapped the effort of moving pebbles for a habit of hanging round on the pavement outside the local harbourfront chippie, waiting for careless customers to let one slip.