Over the last 50 years, the U.S. and Canada have slowly but surely lost 29% of its bird populations — amounting to nearly 3 billion birds. The shocking loss could be a sign of an ecological crisis, scientists said Thursday.
According to a new study published in the journal Science by top ornithologists and government agencies, even common birds such as sparrows and blackbirds have faced declines in North America since 1970.”It’s staggering,” said lead author Ken Rosenberg, a conservation scientist at the Cornell University Laboratory of Ornithology.
Researchers studied 529 bird species over the last half-century to compile the most comprehensive study ever done on North American birds, the journal said. Thanks to the decades of monitoring by researchers and bird enthusiasts across the continent — as well as weather radars — scientists had a huge amount of data to work with.What they found was unexpected. While scientists believed rarer species would be declining, they assumed more common species would be on the rise due to their resilience as well as conservation efforts. But the declines have far outweighed the gains. “We expected to see continuing declines of threatened species,” Rosenberg said. “But for the first time, the results also showed pervasive losses among common birds across all habitats, including backyard birds.”Grassland birds such as meadowlarks and northern bobwhites have declined by 53% since 1970 — a loss of 700 million adults in the 31 species studied. Shorebirds such as sanderlings and plovers are down by about one-third, according to the study.”There’s an erosion of the numbers of common birds,” Rosenberg said. Indeed, 19 common species have lost more than 50 million birds in the last 50 years. Birds such as sparrows, warblers, finches and blackbirds have been hit particularly hard, the study found.”When you lose a common species, the impact will be much more massive on the ecosystem and ecosystem services,” said Gerardo Ceballos, an ecologist and conservation biologist at the National Autonomous University of Mexico in Mexico City. “It’s showing the magnitude of the problem.”Between 2007 and 2017, the mass of birds migrating in the spring has dropped 13%, with the greatest decline in birds migrating up the eastern United States. “We want this to be the real wake-up call,” Rosenberg said.