Source : Webster's Revised Unabridged Dictionary (1913)

Turnstone \Turn"stone`\, n. (Zo["o]l.)
   Any species of limicoline birds of the genera {Strepsilas}
   and {Arenaria}, allied to the plovers, especially the common
   American and European species ({Strepsilas interpres}). They
   are so called from their habit of turning up small stones in
   search of mollusks and other aquatic animals. Called also
   {brant bird}, {sand runner}, {sea quail}, {sea lark},
   {sparkback}, and {skirlcrake}.

   {Black turnstone}, the California turnstone ({Arenaria
      melanocephala}). The adult in summer is mostly black,
      except some white streaks on the chest and forehead, and
      two white loral spots.

Source : WordNet®

turnstone
     n : migratory shorebirds of the plover family that turn over
         stones in searching for food