Over the past half-century, North America has lost more than a quarter of its entire bird population, or around 3 billion birds.
…Their results show that more than 90% of the loss can be attributed to just a dozen bird families, including sparrows, warblers, blackbirds and finches.
Common birds with decreasing populations include meadowlarks, dark-eyed juncos, horned larks and red-winged blackbirds, says Rosenberg. Grassland birds have suffered a 53% decrease in their numbers, and more than a third of the shorebird population has been lost.
…”Just because a species hasn’t gone extinct or isn’t even necessarily close to extinction, it might still be in trouble,” she says. “We need to be thinking about conservation efforts for that.”
The researchers cite a variety of potential causes for the loss of birds, including habitat degradation, urbanization and the use of toxic pesticides, notes Zipkin.