'Arctic unicorns' in icy display

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Remarkable footage of elusive narwhal - creatures best known for their unicorn-like tusks - has been captured.

The BBC filmed the whales during their summer migration, as they navigated through cracks in the melting Arctic sea ice.

The team believes this aerial footage, which forms part of the BBC Natural History Unit's new series Nature's Great Events, is the first of its kind.

Nature's Great Events: The Great Melt is on Wednesday 11 February on BBC One at 2100 GMT