Millions of Birdwatchers Help Uncover a Grim Mystery: Why Are Birds Disappearing from Their Safest Havens?
New research reveals an alarming trend—birds are vanishing fastest from the very places they once thrived. Here's what scientists discovered using 36 million sightings and cutting-edge technology.
In a revelation that’s shaking the foundations of bird conservation, a new study published May 1 in Science shows that North American bird species are suffering their steepest declines not in fragile habitats—but in the heartlands where they were once most abundant.
Researchers from the Cornell Lab of Ornithology analyzed more than 36 million bird sightings collected by everyday birdwatchers through the eBird program, combining these observations with high-resolution satellite data from 2007 to 2021. The result: a continent-spanning portrait of 495 bird species—and a wake-up call for conservation.
“We expected some decline, but not this,” said Dr. Alison Johnston, the study’s lead author. “The most alarming thing is that we’re seeing the biggest losses where birds should be thriving.”
In fact, 83% of bird species examined are declining most rapidly in areas where they were once most numerous.
Not Just a Decline—A Collapse in Safe Havens
The research zeroed in on habitat "strongholds"—regions historically considered ideal for species survival. But many of these areas are now hemorrhaging bird populations.
These include:
Grasslands, where native species have declined amid agriculture and land-use changes.
The Arctic tundra, where climate change is rewriting ecological rules.
“These were our refuges,” Johnston emphasized. “Places where birds used to flourish. And now we’re seeing them fall apart.”
This study follows a string of urgent warnings, including the 2025 State of the Birds report and the landmark 2019 paper that reported the loss of nearly 3 billion birds in the U.S. and Canada since 1970. But where earlier research could only track broad regional trends, this new study breaks it down to 27-by-27 kilometer grids—a scale about the size of New York City.
“This is the smallest resolution we’ve ever achieved across an entire continent,” said Dr. Amanda Rodewald, Director of the Center for Avian Population Studies at Cornell. “It allows us to ask: exactly where are populations changing—and why?”
A Double-Edged Map: Decline and Hope
Despite the grim headlines, the study also revealed a vital sliver of optimism. Nearly every species—97%, in fact—had at least some areas where populations were increasing.
These “bright spots” often occurred in regions where species were previously rare, suggesting the potential for targeted conservation and strategic habitat restoration.
“Where birds are increasing at low abundance, we may be seeing either successful conservation or untapped opportunities for recovery,” said Johnston.
This level of insight was once unthinkable. But with tools like causal machine learning, vast computing power, and passionate birders uploading data daily, scientists can now parse population shifts in stunning detail. The team ran over half a million simulations, totaling 6 million hours of computation—a feat that would’ve taken 85 years on a standard laptop.
Citizen Science: The Secret Weapon
None of this would be possible without the millions of volunteer birdwatchers who contributed their sightings to eBird, one of the largest citizen science platforms on Earth.
“Knowledge is power,” said Rodewald. “Thanks to these volunteers, we know more about birds—and about our environment—than ever before.”
eBird is not just a hobbyist platform—it’s a powerful scientific tool, now critical in addressing one of the largest biodiversity crises on the continent.
The takeaway? We need to stop assuming that areas with lots of birds are safe. Abundance doesn’t equal security.
Why This Matters for the Future of Conservation
This isn’t just about birds—it’s about how we use data, how we prioritize environmental action, and how we harness community science to fight a planetary crisis. By identifying the exact coordinates where species are faltering, researchers and conservationists can now deploy interventions with surgical precision.
“It’s a game-changer,” said Rodewald. “This is the roadmap we’ve been waiting for—one that lets us act swiftly, smartly, and with purpose.”
A Call to Action
If the last few years told us bird populations are in crisis, this study tells us exactly where to look—and where to start fixing it. The birds are sounding the alarm in places we least expected. Now, the question is whether we’re ready to listen—and act.
