The U.S. and Canada have lost almost 3 billion birds since 1970 in what researchers are calling an ecological crisis.
New research, published Thursday in the journal Science, found widespread population declines across North American bird species. The population dips could have ecological, evolutionary and economic impacts, the scientists warn.
Researchers looked at bird-monitoring data set for more than 500 species in North America. The area has lost the equivalent of roughly 1 in 4 birds over the past 50 years. The most drastic population declines come from a dozen bird families like songbirds, which include sparrows and warblers.
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Some species like raptors and waterfowl have seen jumps in their populations, likely due to conservation efforts, according to the study.
The study did not look at potential causes for these declines, but researchers said the losses are likely similar worldwide, which suggests multiple factors could be at play. The researchers also paralleled the loss to a similar downward trend in insects and amphibians.
The crisis “reaches far beyond our individual borders,” study co-author Adam Smith said.
“Many of the birds that breed in Canadian backyards migrate through or spend the winter in the U.S. and places farther south – from Mexico and the Caribbean to Central and South America,” Smith said in a statement. “What our birds need now is an historic, hemispheric effort that unites people and organizations with one common goal: bringing our birds back.”
The study authors, some of whom work at the American Bird Conservancy, Cornell University’s ornithology lab, Smithsonian Migratory Bird Center and other groups, suggested strengthening bird policies, banning harmful pesticides and funding conservation programs.
A separate recent study published in the journal Science found that one of the world’s most widely used insecticides could be hurting the health of songbirds and delaying their migrations.