The continent has lost nearly 3 billion birds representing hundreds of species over the past five decades, according to a study from top ornithologists and government agencies. Peter Marra, director of the Georgetown Environment Initiative, explains this staggering loss. Subscribe to The Washington Post on YouTube: wapo.st/2QOdcqK Follow us: Twitter: twitter.com/washingtonpost Instagram: www.instagram.com/washingtonpost/ Facebook: www.facebook.com/washingtonpost/