But this was written by Carl Zimmer, who's not usually prone to hyperbole, so it's surprising to see him taking an estimate based on amateur logs as fact, and then quoting Rachel Carson, author of the activist Bible called "Silent Spring." (1)
But what does that really mean? First, their estimate may be fine, whereas old estimates were guesses, but that could be like claiming the earth is cooling based on a cheap thermometer reading 50 years ago that might be lower on a more accurate sensor today. Or vice-versa, the diaries from 50 years ago may be better than now. Maybe it's a lot of people who are more like Carson than they are scientists.
If either is true, it's irresponsible to use an old set of estimates in comparison to a modern one and call it data. The authors of the paper know this, editors at Science know this, peer-reviewers know it. And yet this gets published because they also know this well get in the New York Times - they even created a #BringBirdsBack hashtag and a website to promote their claims before the paper was published. Even if it is accurate, and there is no way to know, who writes words like "shocked" about a paper driven by a grant which was proposed to show exactly that. Absolutely no one behind the paper was shocked, they knew the result going in. And Carson's book was not "prophetic" either. No one commissioned the Old or New Testaments, but Carson was hired by a book publisher to write "Silent Spring". She got an advance. She even had a co-author drop out because she was more interested in creating a narrative than providing real information about the ecological effects of pesticides.
Plus, even if the number were real, and we again have no idea if it is, we lose a billion birds a year just to cats and another 500,000,000 to flying into windows. There is even concern about wind power because it supposedly kills so many but clipping the wings of dead bird hype is the only scientifically defensible issue in wind power.
If estimates are anywhere near accurate, 10 billion birds are born here each year. If there are now only an average of 200,000,000 in each state that's no reason to panic. It's reason to write panic papers, sure, but everything related to how awful humans are seems to be a reason to write those.
Zimmer is usually a great journalist, and we can give him a break on this because even Elvis Presley had bad albums, but outrageous 'too good to be true' claims merit more fact-checking, not the kind of "churnalism" we get from Huffington Post or The Guardian.
Science itself does even worse, because they invoke an actual prophet - doomsday prophet Paul Ehrlich, the discredited merchant of doubt whose "Population Bomb" turned out to be a dud but nonetheless promoted discussion of mandatory sterilization, forced abortion, and a world government to solve the problem we never had.
(1) Carson is quoted by earnest people today who think she had science on her side, but actual scientists disagreed. Professor I. L. Baldwin, professor of agricultural bacteriology at the University of Wisconsin and leader of the National Academy of Sciences committee studying pesticides and wildlife, called it a “prosecuting attorney’s impassioned plea for action.”
There is no worse slam you could get from scientists back then. Today, too many in the life scientists trust attorneys more than they trust scientists in food, chemistry, and physics.
His review, ironically, given what they have morphed into, was published in Science, back when it's what they did regardless of how their leadership skewed politically, rather than just being a proper name.