North American bird populations are declining most severely in areas where they should be thriving, according to a groundbreaking study published May 1 in Science.

Researchers from the Cornell Lab of Ornithology set out to develop reliable information about where birds are increasing or decreasing across North America, but the patterns they uncovered were startling.

Birds are declining most severely where they are most abundant – the very places where they should be thriving. Of the species they examined, 83% are losing a larger percentage of their population where they are most plentiful.

“We’re not just seeing small shifts happening – we’re documenting populations declining where they were once really abundant,” said Alison Johnston, lead author and ecological statistician who initiated this study as a research associate at the Cornell Lab of Ornithology. “Locations that once provided ideal habitat and climate for these species are no longer suitable. I think this is indicative of more major shifts happening for the nature that’s around us.”

Johnston is now a faculty member at the University of St. Andrews, Scotland.

The Lab of Ornithology team analyzed 36 million bird observations that birdwatchers shared to the Cornell Lab’s eBird program, along with multiple environmental variables derived from high-resolution satellite imagery for 495 bird species across North America from 2007–2021.

This news follows on the heels of other recent research that documented widespread losses of birds in North America. The 2025 U.S. State of the Birds report showed bird declines in almost every biome