Beavers were hunted and disappeared from Britain around 400 years ago.
In Scotland, they were first reintroduced in 2009 as part of a trial, and now enjoy protected status. But their appetite for destruction has led to conflict with some farmers and landowners.
A trial in Devon ends next year, when a decision will be made whether or not to extend it to other parts of England.
UK viewers can watch the full programme for 30 days from transmission