The Thick-billed Murre or Brünnich's Guillemot (Uria lomvia) is a bird in the auk family (Alcidae). It breeds on coasts and islands in the High Arctic of Europe, Asia and North America, where it is one of the most numerous bird species. From their high Arctic breeding grounds the species is migrating by both flying and swimming (also ocean currents) to their sub-arctic wintering grounds. E.g. the birds from Svalbard are wintering in the waters south of Greenland and in the Labrador Sea.