Catch up TV

Series 2: 2. Tywi

Iolo heads up the Tywi river valley. His 75-mile journey begins at the coastal village of Llansteffan, where the river meets the sea under the watchful gaze of its 12th century Norman castle. Along the area of dune between the beach and the village, Iolo encounters a stonechat, a small, hardy bird that vigorously defends its territory with a call like two stones clicking together. \n\nThe Tywi suffers from water quality issues like most UK rivers, and Iolo stops to observe a significant algae bloom along the banks near Carmarthen, a direct result of excessive nutrients from sewage water and agricultural runoff that threaten the river's delicate ecosystem. Following the river inland through the fertile lowlands, Iolo visits Bishop's Pond, by Abergwili. This tranquil oxbow lake, once part of the main river, is now a thriving wetland. Here, Iolo delights in the vibrant colours of damselflies and dragonflies patrolling the water's edge.\n\nA major highlight of the journey occurs at Dinefwr Park near Llandeilo, where Iolo heads into the parkland during the autumn for the fallow deer rutting season. He is treated to a spectacular view of a dominant buck as it uses his deep, belching groans to hold his group of does together. \n\nAbove the valley floor, Iolo meets a drystone waller rebuilding a section of wall dating back to the 1700s at Taliaris. On the opposite side of the valley, Iolo visits Garn Goch, a huge iron age hillfort, and sees birds that have disappeared from most of the Welsh countryside. \n\nMoving further upstream to a quiet tributary, the River Sawdde, Iolo meets officers from Natural Resources Wales surveying the river, and discovers a glimmer of hope for the catchment's future: a healthy population of juvenile salmon and other fish species amongst the oxygen-rich gravels. \n\nThe adventure continues into the heart of the Cambrian mountains at the RSPB Gwenffrwd-Dinas reserve. In this enchanting ancient oak woodland, Iolo gently holds a cockchafers beetle, also known as a maybug, in his hands. This large beetle has become scarce in recent years, and is a three course meal for bats. He also finds a wood warbler, a speciality of these temperate Welsh rainforests, whose shivering song is amazing to hear. \n\nAs the river narrows and the landscape becomes even more rugged, Iolo enters the vast Tywi forest. The journey concludes near the river's remote source in the Cambrian mountains, a landscape where the Tywi begins its life as a tiny stream. Here, Iolo reflects on a journey rich in history as it is in natural wonder.

Source: BBC 2