Iolo Williams explores Anglesey by land and by sea to look for the rich diversity of wildlife on Wales' largest island. He also discovers why it has some terrific rare species.

Chapter 1:
Renowned for its coastal beauty, Anglesey also has fantastic marshland and heathland with spectacular wildlife. Iolo observes breeding marsh harriers - majestic birds of prey that have only recently started to nest in Wales. He also finds stoats, grey seals and lizards. Iolo also visits Puffin Island to find the only breeding site in Wales for eider ducks. On a disused railway line, he finds breeding adders.

Chapter 2:
Iolo goes by boat to Ynys Badrig, an offshore island which is the northernmost point of Anglesey and Wales and the potential site of new gannet colony. He also explores a stunning wood at the centre of Anglesey with carpets of spring flowers and native red squirrels. The presenter watches peregrines on the Menai Straits, and on wetlands near RAF Valley, find nesting sand martins, spots otters and enjoys a rare sighting of a bittern.

Chapter 3:
On the sand dunes, rocky cliffs and surrounding farmland there's also spectacular wildlife. Iolo Williams finds colourful day-flying moths, beautiful orchids and brown hares. He also heads out to the Skerries Islands and visits Wales' only Arctic tern colony. Near an abandoned farm outside Holyhead, he also finds a fox and a little owl with its chick.

Chapter 4:
Anglesey also has stunning fenland and rich surrounding sea full of terrific wildlife. Iolo heads out to sea to look for Risso's dolphins, where underwater, an artificial reef has formed from an old shipwreck. Iolo finds roosting bats at an old priory, plus dragonflies and beautiful rare plants on Anglesey's fens. On the Alaw estuary, Iolo gets a rare sight of a merlin - Britain's smallest bird of prey as well as Brent geese, which have flown all the way from Canada to overwinter on Anglesey.