Why some birds migrate and some do not...
BBC Sounds ‘In our time’ podcast explains, with the help of experts, the history of how we came to discover the truth about bird migration. As recently as the 1800’s, theories included the idea that birds travelled deep under water, turning into fish, or hibernating while clinging to trees upside down. It’s a fascinating story.
https://www.bbc.co.uk/programmes/b08wmk5j
And an Altas Obscura clip about the Arrow Stork’s important role in the story