Billions of birds have vanished in North America since 1970 in ‘full-blown crisis

Billions of birds in North America are gone, silently disappearing over the last 50 years, raising concerns that common birds like sparrows and blackbirds could one day disappear.

That's according to a new study published Thursday in the journal Science by American and Canadian researchers who reported that 3 billion, or 30%, of the birds on the continent have vanished since 1970 due mainly, but not only, to habitat loss and pesticide use.

"The findings raise fears that some familiar species could go the way of the passenger pigeon, a species once so abundant that its extinction in (the) early 1900s seemed unthinkable," the researchers wrote in the study summary.

Scientists used weather radar data, 13 different bird surveys dating back to 1970 and computer modeling to project bird populations and trends for almost 530 species of North American birds, ABC News reported.

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.