The journey south can be over , so a 50-year-old bird has probably covered over a million km (600,000 mi) on migration alone. The migration also appears to be quite complex, containing many stopovers and foraging zones throughout the Atlantic Ocean. Ornithologist Chris Mead estimated that a bird ringed in 1957 when aged about 5 years and still breeding on Bardsey Island off Wales in April 2002 had flown over 8 million km (5 million mi) in total during its 50-year life.