September 1, 2014 marks the 100th anniversary of the extinction of the Passenger Pigeon. At the beginning of the 19th century, there were billions of Passenger Pigeons in North America, so many, in fact that their flocks are described as blackening the sky when they flew overhead. Less than a century later, the species was extinct in the wild with only a handful of individuals left in aviaries and zoos around the country. We can pinpoint the moment of their extinction because the last of her species, Martha the Passenger Pigeon, died on September 1, 1914 at 1 o’clock in the afternoon at the Cincinnati Zoo. Here are ten more surprising facts from Errol Fuller, an extinction expert and author of The Passenger Pigeon.