It's autumn 2022, and Scotland's ospreys are continuing their epic annual migration south. They've flown their nests in the Scottish Highlands, traversed the length of the UK, down through Western Europe and across the Strait of Gibraltar to Africa. Now they face one of their biggest challenge yet: crossing the Sahara desert, and on still further to their wintering grounds in the mangrove swamps on the lush coast of Guinea. Many attempt the journey, 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, the team take on the challenge of the West African coastline - through lush wetlands and the harsh heat of the Sahara, through mangrove swamps teaming with life and the tangled waterways of Guinea. 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