Ibis - international journal of avian science, 23 Aug 2017 The first 50 years of the North American Breeding Bird Survey http://ow.ly/kajw30eiYn3
U.S. Geological Survey (USGS), 01 Aug 2017 In the first 50 years of the North American Breeding Bird Survey (BBS) https://www.pwrc.usgs.gov/bbs/ it has monitored change…