American and Canadian bird populations have decreased 29% in the last 50 years, finds a study just published by Cornell University researchers in the journal Science.

All together, the population is down by 2.9 billion breeding adult birds.

Researchers day the losses are driven primarily by habitat loss.

A billion of those birds formerly lived in forests, and 700 million in grasslands.

More than 90 percent of the losses come from  12 commonly known bird species, including sparrows, blackbirds, warblers and finches.

Dark-eyed juncos (little gray snowbirds) and meadowlarks were among the hardest hit, with 160 million and 130 million lost respectively.

“It’s a strong signal that our human-altered landscapes are losing their ability to support birdlife,” said Ken Rosenberg, lead author and conservation scientist at the Cornell Lab of Ornithology in a press release.

“And that is an indicator of a coming collapse of the overall environment.”

“It’s telling…