The Arctic tern, a bird that weighs just 4 ounces (113 g), is the animal that has the longest migration. Migration is the seasonal travel of animals, generally from one climate to another, in order to take advantage of needed resources. Arctic terns travel from the North Pole to the South Pole and back, for a distance of about 44,000 miles (70,800 km) annually. It is unknown why they choose to migrate such a long distance. The birds typically start their migration in Greenland, then fly south to Antarctica for about five months before heading back north.
More about migration:
- Birds often double their body weight before migration to increase their body’s fuel reserves, which tends to be their main source of energy rather than stopping to forage for food.
- The mammals with the longest migration are northern elephant seals and gray whales, which migrate about 13,000 miles (about 20,922 km) round trip per year.
- Arctic terns live an average of 30 years, and it is estimated that they migrate about 1.5 million miles (2.4 million km) throughout their lives — or the equivalent of three trips to the moon and back.