The animals of Iceland include the Icelandic sheep, cattle, chickens, goats, the sturdy Icelandic horse, and the Icelandic Sheepdog, all descendants of animals imported by Europeans. Wild mammals include the Arctic fox, mink, mice, rats, rabbits, and reindeer. Polar bears occasionally visit the island, travelling from Greenland on icebergs, but no Icelandic populations exist. In June 2008, two polar bears arrived in the same month. Marine mammals include the grey seal (''Halichoerus grypus'') and harbour seal (''Phoca vitulina'').