Passenger Pigeons from the Denver Museum of Nature & Science (image) University of California - Santa Cruz Share Print E-Mail Caption The historical population of passenger pigeons in North America was estimated to be 3 to 5 billion. Their huge flocks darkened the sky. Yet by the early 1900s they had disappeared from the wild, and the last captive bird died in 1914. Credit Rene O'Connell Usage Restrictions For use only with news coverage of this research Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.