A Third of North America's Birds Have Vanished

https://nautil.us/a-third-of-north-americas-birds-have-vanished-340007/

At first Adam Smith couldn’t believe his calculations. Then it sank in.

BY ANDERS GYLLENHAAL & BEVERLY GYLLENHAAL

June 30, 2023

For weeks, Adam Smith had been crunching the raw data from more bird statistics than anyone had ever tried before—thirteen different bird counts and millions of radar sweeps. Suddenly he heard the musical chime that tells him his results are ready. He leaned across his desk, surrounded by enough high-powered computers to heat up his entire office, and stared at what could only be an impossible conclusion: Over the past fifty years, his calculations found, a third of North America’s birds had vanished. “Well, that can’t be right,” he thought. “I must have made a mistake somewhere.”

Smith, one of the hemisphere’s top specialists in bird populations, just sat for a while in his cluttered cubicle at the Canadian Wildlife Service, which was decorated with caribou antlers, a musk-ox skull, and early drawings from his twin boys. Then it dawned on him. “This would be a massive change, an absolutely profound change in the natural system,” he said. “And we weren’t even aware of it.”

Up until that point, counting the abundance of individual birds throughout the entire continent was impossible. At any given time, many species number in the tens of millions in North America—adding up to billions of birds—and they’re constantly on the move. But the science of bird study was advancing, and a close-knit group of scientists was experimenting with using radar imagery, satellite photos, and citizen science to add precision to the dozens of conventional bird counts done for groups of species.

The computation Smith had just finished that day in May 2019 combined individual population estimates for 529 bird species, from the most common sparrows and robins to rarities hardly ever seen. When Smith pulled these estimates together and adjusted each for its degree of certainty, the findings came down to a single ski slope of a chart. It showed a precipitous drop in nearly all these species in every part of the continent. At the bottom sat four lone digits—2.913. That’s the number of breeding birds in billions that had disappeared since the early 1970s. He had documented an accelerating churn of seasonal losses that slowly took their toll on the abundance of birds. And it translated to an astounding third of the adult birds that not long ago filled North America but now are gone.

It's from the book "A Wing and a Prayer" (2023)
Not a book plug. They said nothing about the book until the end of the article.

Anyway, here's the blurb.
Description:
A captivating drama from the frontlines of the race to save birds set against the devastating loss of one third of the avian population.
Three years ago, headlines delivered shocking news: nearly three billion birds in North America have vanished over the past fifty years. No species has been spared, from the most delicate jeweled hummingbirds to scrappy black crows, from a rainbow of warblers to common birds such as owls and sparrows.

In a desperate race against time, scientists, conservationists, birders, wildlife officers, and philanthropists are scrambling to halt the collapse of species with bold, experimental, and sometimes risky rescue missions. High in the mountains of Hawaii, biologists are about to release clouds of laboratory-bred mosquitos in a last-ditch attempt to save Hawaii's remaining native forest birds. In Central Florida, researchers have found a way to hatch Florida Grasshopper Sparrows in captivity to rebuild a species down to its last two..