It's autumn 2022, and Scotland's ospreys are setting off on their epic annual migration south. From peaceful Loch Garten in the highlands they'll head down the length of the UK, cross the channel into Europe, across the Strait of Gibraltar to Africa, and still further, to their wintering grounds in the mangrove swamps on the lush coast of Guinea. Many will leave, but they won't all make it. It's a route that's fraught with danger, both natural and man-made. Only 1 in 3 ospreys who take it on will live to return the following spring.

But this time, they're not doing it alone. A team of conservationists headed up by biologist Sacha Dench are following them every wing-beat of the way, on a mission to discover as much as possible about the journey, and the challenges they face along the way. Climate change is making weather patterns less predictable, crucial wetlands on their route are being poisoned by pesticides and depleted by drought and the birds have the unfortunate habit of electrocuting themselves when they land on powerlines with freshly caught fish. Emily Knight follows the birds, and the people, on their extraordinary journey.

In this episode, we meet the team taking on the challenge, and follow them as they travel down the length of the UK and into Europe. Through wetlands and river-valleys, forests and mountain ranges, protected landscapes and the harshness of the built human environment. At every turn, they meet people who love and care for the birds they share their homes with, and hear stories of the length they've gone to to protect them.

Producers: Emily Knight and Alasdair Cross Show less