Longest mammal migration: Russia-to-Mexico gray whale journey leads to mystery (VIDEO).

The Longest Mammal Migration Ever Recorded Creates a New Puzzle for Biologists

The Longest Mammal Migration Ever Recorded Creates a New Puzzle for Biologists

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April 16 2015 12:30 PM

The Longest Mammal Migration Ever

How a Russia-to-Mexico journey complicates everything we know about gray whales.

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A female from a group of gray whales has been observed traveling from Russia to Mexico and back, a journey that astonished the scientists who tracked her. Watch the video above to see how the record 14,000-mile, 172-day trip upends some long-held beliefs about gray whale populations and could mean a historic group is actually extinct.

Rachel Stewart is an editor who lives in Philadelphia. Check out her work here.