The Arctic Tern earns the No. 1 spot for longest migration of any animal, covering a staggering 44,000 miles in its zig-zagging migratory route each year from Greenland to Antarctica and back again.
The longest migration for a mammal is by the gray whale. In 2011, a gray whale was recorded covering 14,000 miles from Russia to Mexico and back, establishing the record for longest migration by any mammal. The previous record holder was the 11,000-mile migration that a humpback whale recorded earlier the same year.