U.S., Canada have lost 3 billion birds since 1970. Scientists say ‘nature is unraveling.’
For a study published Sep. 19 in the journal Science, Marra joined with other scientists and conservationists to analyze nearly five decades of population data on 529 species of North American birds. The results were staggering: Since 1970, the continental U.S. and Canada have lost more than 1 in 4 birds. The total bird population in the two countries has fallen by almost 3 billion, with grassland birds such as western meadowlarks and American sparrows and shorebirds such as green herons taking the biggest hits.