The Fairy Tern is white, except for the crown which is black from bill to nape. The bill is orange-yellow and the legs are dull yellow. The sexes are similar. In non-breeding plumage the crown is largely white, mottled black and the bill is blackish at the base and tip. Immature Fairy Terns are similar to non-breeding adults. Young birds are similar to immatures, but upperwing coverts and mantle are mottled grey and brown. Also known as Nereis Tern, White-faced Tern, Little Sea-swallow, Sea-swallow or Ternlet.