We're back on the water with Colin Stafford-Johnson, and tearing up the Shannon one last time as he concludes his wonderful two-part documentary series at the source of Ireland's most famous river. Above the water it's all about the birds, with migrant whooper swans, great crested grebes, cormorants and starlings providing the entertainment, while the mating antics of the freshwater crayfish are captured by cameras that venture beneath the surface. Plus, there's a very special display of acrobatics from a red squirrel.