Nearly 3 billion birds have disappeared from North America since 1970, new research shows, with even common species like sparrows and blackbirds suffering massive declines — a “sobering” new chapter in the global biodiversity crisis.Most public attention is focused on extinctions, when all individuals of a species disappear forever. But the team behind the new research, published Thursday in the journal Science, instead undertook a detailed accounting of gains and losses for 529 species of birds in Canada and the United States using long-running surveys and a network of weather radars.They found a decline of 29 per cent over five decades — a net loss of 2.9 billion individual birds out of approximately 10 billion alive in 1970. Biologists and ecologists have long known that many bird species are in decline, but the Science paper offers a startling new perspective on the magnitude of the problem.“That 3 billion number was — wow,” said Adam Smith, a study co-author and senior biostatistician at the Canadian Wildife Service, Environment and Climate Change Canada.Forest birds, grassland birds, shorebirds, and even invasive species — birds that inhabit incredibly diverse environments — all suffered massive declines, he points out. Sparrows, blackbirds, and finches accounted for a huge chunk of the total loss.“Common birds, that we still see almost everywhere we go, even those species are in decline.”The dwindling of even common species raises concerns about the scarcity of animals who play a critical role, and also fears that this pattern may not be exclusive to birds.“They’re integral components of every ecosystem. They do pest control, pollination, seed dispersal,” says Ken Rosenberg, the study’s lead author and a conservation scientist with the Cornell Laboratory of Ornithology and the American Bird Conservancy. “They’re so interwoven with everything else that if ...
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