1/30 Five million swallows swirl above rural Nigeria, poised to migrate to Europe.
BBC Radio 4
Henning Wehn investigates 'Ostrock' - the East German rock and pop music scene.
Nick Ross investigates the health impact of the Chernobyl nuclear power plant accident.
Christine Finn explores how authors' archive is kept, now they write on screens not paper.
A look at the stats behind the Deepwater Horizon disaster, plus an update from the Arctic
BBC World Service
The story of the rescue of a group of Ugandan women who were trafficked into Iraq
Claudia Hammond searches for happiness by delving into the world of positive psychology
How Polish society coped a year after losing its political elite in the Smolensk air crash
Can the message of Easter help Christians overcome the fear of death?
Can the fast decline of Britain's commercial fishing industry be prevented?