Searching for 'the rarest bird in the world'
5 July 2016 Last updated at 08:20 BST
More than a quarter of a century ago a British expedition unearthed a unique bird's wing in the mud of the plains of Ethiopia.
It was the only evidence of the existence of the Nechisar Nightjar - a species of bird that had never been seen before.
This wing became a totem for devoted birdwatchers like the Vernon Head from South Africa, who set off on a mission to find the elusive bird.
Find out more about how they were made here.