Rosenberg led a research team of scientists from seven institutions from the U.S. and Canada in the analysis of 529 bird species. The team analyzed the most robust synthesis of long-term-monitoring population surveys ever assembled for a group of wildlife species; it also analyzed radar imagery.

Rosenberg said the results of this study point to something bigger than birds.

“It’s a strong signal that our human-altered landscapes are losing their ability to support birdlife,” he said. “And that is an indicator of a coming collapse of the overall environment.”

All told, the U.S. and Canadian continental avifauna population is down by 2.9 billion breeding adult birds, with devastating losses among birds in every biome. Forests alone have lost 1 billion birds. Grassland bird populations collectively have declined by more than 50 percent, or another 700 million birds.