The bird population in the United States and Canada has decreased by 29 percent since 1970, according to the findings of a new study released Thursday.
The study, published in the journal Science, found that change means there are 2.9 billion fewer birds than five decades ago.
The study was the most in-depth investigation scientists have conducted to determine what is happening to the planet’s birds. Over 500 species were surveyed for the analysis.
{mosads}David Yarnold, president and chief executive of the National Audubon Society, described the massive drop as a “full-blown crisis,” in a statement Thursday and called for action.
“This is a full-blown crisis that requires political leadership as well as mass individual action. We have to act now to protect the places we know birds rely on,” Yarnold said.
Using data from the study, The New York Times published a graphic breaking down the population loss based on region. The bird population in the grasslands region — roughly Texas, part of the Midwest, plains states and an area of south-central Canada — was hit the hardest, with a loss of 717 million birds.
Researchers have pinpointed likely causes for the avian decline, citing increased agricultural development, which causes the loss of bird habitats, and the use of pesticides.
“Every field that’s plowed under, and every wetland area that’s drained, you lose the birds in that area,” Kenneth V. Rosenberg, a conservation scientist at Cornell University, said to the Times.
Despite the widespread population loss, the study showed some species actually experienced growth. Most notably bald eagles, which are no longer considered endangered.