By John Balson @JJBalson
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Videographer / Director: Michael Ethridge
Producer: John Balson, Dan Howlett, Chloe Browne
Editor: Ian Phillips
The 400lb bear had been lazily walking along a path when it suddenly reared up on its hind legs and started writhing by a road sign.
The animal's rhythmic motion lasted more than 10 seconds and made it appear as if it was performing a funky dance routine like pop star Beyoncé Knowles.
The bizarre scene was filmed by Michael Ethridge during a drip to South Dakota with his wife, Mimi, and teenage grandsons Jon and Sam.
He said: "We were driving through bear country and caught this grizzly in front of our vehicle.
"We had been following it for a few minutes when the bear stood up and started scratching its back on a pole in a really funny way.
"I was amazed. The boys were going berserk in the back seat. Our friends think it is the funniest video ever."
Mr Ethridge from Birmingham, Alabama, filmed the incident in July 2014 but has only just made it available.