It's not just a species tally — all birds are counted all day, giving an indication of the total number of birds in the circle that day. (scientificamerican.com)
Both kill large number of birds each year; solar also results in significant toxic contamination. (carlineconomics.com)
During their surveys, researchers found similar numbers of bird species in secondary stands compared to stands comprised entirely or in part of old - growth forest. (sciencedaily.com)