Iolo Williams explores the Welsh Marches, the borderlands with England, discovering amazing wildlife in this surprisingly diverse area.
In the Gwent Levels, he is treated to a chorus of birdsong and hunts for one of the rarest bees in Britain - the shrill carder bee. In the Wye Valley, he sets trail cameras to capture shots of elusive wild boar and searches for the rare hawfinch and camouflaged nightjar.
Iolo ends this portion of his journey at Llanthony Priory, where house martins are nesting in the ruins.