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For the first time, researchers have estimated the volume of total avian loss in the Western Hemisphere—and it’s not just threatened species that are declining. Many backyard favorites are also losing ground.
Almost anywhere you go, you can find birds. They scurry through the waves on every beach, sing as they wing over every prairie, raise chicks in nests in every wood, and visit every backyard. But while birds remain everywhere, people are actually seeing far fewer of them than just 50 years ago, according to a new study. It estimates that North America is home to nearly three billion fewer birds today compared to 1970—that’s more than 1 in 4 birds that have disappeared from the landscape in a mere half a century.
“This was an astounding result, even to us,” says lead author and Cornell Lab of Ornithology conservation scientist Ken Rosenberg.
The study, published today in the journal Science, marks the first time experts have tried to estimate sheer numbers of avian losses in the Western Hemisphere. Typically, conservation studies focus on a specific species, habitat, region, or type of threat. By taking a higher-level view, the study highlights that many birds we still consider common, ranging from Baltimore Orioles to Dark-eyed Juncos to Barn Swallows, are actually posting heavy population losses over time.
Altogether, the research team—which included collaborators at the American Bird Conservancy, Smithsonian Conservation Biology Institute, U.S. Geological Survey, the Canadian Wildlife Service, and other institutions—analyzed the breeding population of 529 species by pooling data from the North American Breeding Bird Survey, Audubon’s Christmas Bird Count, U.S. Fish and Wildlife Service waterfowl surveys, and 10 other datasets. They also analyzed more recent data collected by weather radar technology that can track large groups of birds as they migrate to estimate their numbers.