6/6 Whales and sea lions alike journey to the seas off Alaska to feed on the plankton bloom.
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5/6 The great flood in the Okavango turns 4,000 square miles of arid plains into a wetland.
4/6 A look at the sardine run, which happens each winter along the South African coast.
3/6 The story of a lion family's struggle to survive until the return of the great migration.
2/6 A look at the annual return of millions of salmon to the streams where they were born.
1/6 The summer melt of Arctic ice provides opportunities for millions of animals.