The study found bird populations suffering some of the largest losses included warblers, blackbirds, sparrows, eastern and western meadowlarks and Bobwhite quails, according to news reports.
"This is a landmark paper. It's put numbers to everyone's fears about what's going on," Joel Cracraft, the curator-in-charge of ornithology at the American Museum of Natural History, who didn't participate in the study, told ABC.
"It's even more stark than what many of us might have guessed," Cracraft said.
Conservation biologist Kevin Gaston went even further, telling The New York Times something even larger is at work.
"This is the loss of nature."
The dire statistics in the study are a seeming fulfillment of Rachel Carlson's seismic 1962 book "Silent Spring," which sparked the American environmental movement and predicted a mass decline in bird populations from chemicals and pesticides, if no intervention was taken.
Birds are integral to a healthy environment. They eat and thereby control pesky insects, pollinate flowers and spread seeds. Even after death, they provide food for scavengers. The Audubon Society puts it this way: Birds help keep our ecosystems in balance.