Wildlife cameraman and filmmaker John Aitchison sets up his hide near a partially-frozen lake in Missouri, Midwestern United States, and waits for flocks of Lesser Snow Geese to fly over. Its spring and the birds are on migration. Lesser Snow Geese are one of the commonest birds in America; there are more than 5 million breeding pairs. Watching their huge flocks has been likened to watching snowflakes in a storm; there are just too many birds to count, and yet when the first Europeans arrived in America, populations of the Passenger Pigeon numbered billions not just millions. The early settlers could look up at the sky and see flocks of passenger pigeons as dense as these geese pass over, not just for minutes but for hours or even days. It's hard to imagine such a huge abundance of birds. One nesting colony reportedly covered 850 square miles.
The last passenger pigeon, a bird called Martha who was born and lived in captivity at Cincinnati zoo, died just over 100 years ago on Sept 1st 1914. In this programme, John travels to the States to see Martha, (after her death, she was packed in ice and sent to the Smithsonian Institution in Washington DC where she was preserved and is now kept) and learns about the history and lives of the Passenger Pigeons and discovers the causes of their extinction (a combination of deforestation, hunting, railroads, refrigeration and human greed). A century on, John reflects on what lessons we have learned from the birds' demise and explores the possibility of bringing the passenger pigeon back from extinction, using genomic technology and a living relative, the band-tailed pigeon. It's a fascinating and sobering journey; as John says when he comes face to face with Martha; "Extinction is a terrible thing". Producer Sarah Blunt.