Longest migration by a bird
Who
Unknown
Where
Arctic Arctic circle
When
The Arctic tern (Sterna paradisaea) migrates the greatest distance of any bird species, breeding north of the Arctic circle and then flying south to the Antarctic for the northern winter and back again, a round trip of approximately 80,467 km (50,000 miles). They make this journey to spend a second summer in the sourthern hemisphere so they can use the long daylight hours for feeding. Most terns travel by sea, feeding as they go, but some do take overland routes such as the Marsh tern which flies over the Sahara.