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The number of birds in North America has declined by almost 3 billion since 1970, according to a study published today (September 19) in Science. The work, led by researchers at Cornell University, documents population reductions for hundreds of species and warns of an ongoing biodiversity crisis across the continent.
Paul Ehrlich, an ecologist at Stanford University who was not involved in the work, tells Science that the findings “might stir needed action in light of the public interest in our feathered friends.”
The researchers estimated changes in the populations of 529 species using long-term bird-monitoring databases. Those data showed that the number of individual birds across all of those species had decreased by 29 percent, from around 10 billion in 1970 to just over 7 billion in 2017.
“The datasets they used provide probably the best long-term, large-scale information on species abundances for any group ...
