Black bears are often considered among the most dangerous animals in North America, depicted down the years as ferocious predators threatening to man.

But, says one man, that perception could not be further from the truth.

For 43 years, Professor Lynn Rogers has studied wild bears, walking and playing with them, gaining amazing insights into their behaviour.

His studies reveal the bears as peaceful, playful creatures, which even hum when they are content.

The new understanding of wild black bear (Ursus americanus) behaviour unveiled by Prof Roger's research is depicted by the BBC natural history programme Natural World: "Bearwalker of the Northwoods".