United States – Researchers documented a troubling speedup in bird population losses across North America, with three U.S. regions emerging as critical zones of concern.[1][2]
The Alarming Speedup in Losses
Scientists analyzed data from over 1,000 North American Breeding Bird Survey routes spanning 1987 to 2021 and found that bird abundance dropped by an average of 15% per route continent-wide.[1] Among 261 species tracked, 122 – nearly half – registered significant declines, and 63 of those losses accelerated over time.[2] This pattern extended beyond individual birds to entire families and habitats, including marshes and open woodlands.
Lead author François Leroy, a postdoctoral researcher at The Ohio State University, emphasized the shift. “We are not talking about the decline but the acceleration of the decline,” he stated. “We see that this decline is getting faster and faster with the intensification of human activities.”[2]
Common species felt the impact, such as red-winged blackbirds, house finches, and American crows, alongside adaptable types like European starlings and house sparrows.[3]
Mapping the Three Critical Hotspots
The study pinpointed regions where declines quickened most dramatically, all tied to heavy agricultural presence.
- Mid-Atlantic states, including Delaware, Maryland, and New Jersey;
- Midwest areas, such as Indiana, Ohio, Kentucky, Illinois, Wisconsin, and Michigan;
- California, a vast agricultural powerhouse.[1]
These hotspots contrasted with pockets of stabilization, like parts of New England and the Pacific Northwest, where losses slowed.[4] Southern states like Florida, Texas, Louisiana, and Arizona saw the steepest overall drops, though not always the fastest acceleration.
Agriculture Intensity Fuels the Crisis
High cropland coverage, fertilizer application, and pesticide use aligned closely with accelerating declines, researchers reported.[1] Farmland consolidation since the 1980s has intensified practices without expanding total acreage, fragmenting habitats and harming insect prey for many birds.
Co-author Marta Jarzyna of Ohio State noted the breadth of the problem. “Agriculture intensity is the main driver associated with accelerated loss of abundance,” she said, though pinpointing one factor proved challenging in the analysis.[4] Insect populations, down over 40% in some areas, compounded the threat to insect-dependent species.
Climate Change Compounds the Pressure
Warming temperatures correlated with broader declines, particularly in southern regions, and amplified agriculture’s effects where heat rose most sharply.[3] Jarzyna observed, “In regions where temperatures increase the most, we are seeing strongest declines in populations.”
The interplay suggested that hotter conditions worsened habitat loss from farming, creating a vicious cycle for avian life.
What Lies Ahead for North American Birds
Birds deliver vital services, from pest control to seed dispersal and pollination, making their losses a warning for ecosystems and human food systems alike.[2] Forest birds showed relative resilience, hinting at recovery potential through targeted restoration.
Key Takeaways
- Bird abundance fell 15% per survey route from 1987 to 2021, with acceleration in 63 species.[1]
- Agricultural hotspots – Mid-Atlantic, Midwest, California – drive the speedup.
- Reducing pesticides and fostering diverse farming could halt the trend. Read the full study in Science.[1]
This study builds on a 2019 finding of 2.9 billion birds lost since 1970, urging immediate shifts in land use and emissions.[2] Protecting adaptable species signals a healthier environment for all. What steps should policymakers take next? Tell us in the comments.
