Chris looks at freshwater animals. In the Highlands, Chris witnesses a fabulous fishing display by ospreys and, in Poole Harbour, learns how to tempt them to nest much further south. He investigates what white faced darter dragonflies, black water voles and brown trout can tell us about the changing nature of our waterways. And he discovers the grisly truth behind why beavers became extinct here, some 400 years ago.