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Animal behaviour expert Shaun Ellis spent 18 months living with a pack of wolves in the Rocky Mountains of America.

This former soldier with the British Army Special Forces was tough, fit and had some experience of living in the wild.

However nothing could have prepared him for his extraordinary time with the wolves, whom he had to depend on them for survival and behave in every way, like a low-ranking member of their pack.

Lucy Ash talked to him about learning to stomach their diet, the importance of smell and interpreting wolf howls.

The Man Who Lives With Wolves by Shaun Ellis with Penny Junor is published by Harper Collins.