Autumnwatch returns for a celebration of UK wildlife.

Chris Packham and Kate Humble are on a mission to track down one of the UK's biggest autumn wildlife spectacles - vast flocks of roosting starlings. Using cutting-edge technology, the team uncover the secret of their stunning aerial displays, and try to get inside the roost. Across the country, wildlife is massing in vast numbers, and there is a guide to the top spectacles of the season.

Meanwhile in Wales, guest presenter Iolo Williams reveals the surprising and mysterious life of the region's most iconic fish, the sea trout. Show less