Quieter Skies Ahead: New Research Reveals Accelerating Bird Declines 

Bird populations across North America are declining faster than previously understood, according to new research published in Science, with lead author François Leroy. By analyzing more than three decades of monitoring data, researchers found that nearly half of the species studied are experiencing significant population decline with many of them accelerating.

Researchers analyzed more than three decades of data from the North American Breeding Bird Survey, examining trends for 261 bird species across 1,033 monitoring routes from 1987 to 2021. What they found was alarming: nearly half of the species studied—122 species—show significant declines, and for many of them the drop is speeding up over time.

The losses are not evenly spread. Instead, they cluster in three major regions: the Midwest, California, and the Mid-Atlantic. These areas share one defining feature: high-intensity agriculture.

Why North America’s Birds Are Disappearing Faster Than Expected

“Intense agriculture use can accelerate the abundance decline that may be primarily driven by climate,” said François Leroy, a postdoctoral researcher in ecology at The Ohio State University and researcher with the AI and Biodiversity Change Global Center. The researchers compared bird population trends with factors such as climate, land cover, fertilizer use, pesticide use, and human development. Agricultural activity repeatedly emerged as the strongest predictor of where bird declines were speeding up.

A System-Wide Problem

The findings challenge a common assumption that bird declines mainly affect a few vulnerable species. Instead, the pattern appears widespread across the avian family tree.

“The pattern is not driven by a few taxonomic groups with shared traits or evolutionary histories, but is instead widespread across families,” Leroy explained, suggesting that the problem is not isolated to farmland birds alone but affects many types of birds with different ecological roles.

Overall, researchers estimate a 15% drop in bird abundance per monitoring route across North America during the study period. That might sound small, but at continental scale it represents enormous ecological change.

Birds play an important role in ecosystems. As the authors note, “absolute bird numbers are linked to ecosystem services.” When populations decline, the ecological functions those birds support across food webs may decline as well.

Why Farming Matters

Modern agriculture has transformed landscapes across North America. Large-scale monocultures, fertilizer runoff, pesticide use, and habitat loss can reduce food sources and nesting sites for birds. Regions with intensive agricultural activity consistently showed the most rapid bird population losses.

For conservation scientists, that pattern may help focus solutions. If hotspots of decline are geographically concentrated, targeted land-management strategies—like restoring habitat edges, reducing pesticide use, or leaving field margins for wildlife—could make a measurable difference.

Despite the troubling findings, researchers say the story isn’t over.

The findings highlight the importance of looking beyond simple population declines. As the authors note, “our findings suggest that such dynamics could represent a critical, yet unexplored, dimension of ecological responses.” By examining not only whether populations are declining but also whether those declines are accelerating, scientists may uncover warning signs that would remain hidden if they focused only on overall abundance trends.

For now, though, researchers warn that the silence spreading across parts of North America’s landscapes should serve as a wake-up call. The birds are still here but their numbers, and their songs, are fading faster than we thought.

Co-authors include: Marta A. Jarzyna, Petr Keil

Read the publication: Acceleration hotspots of North American birds’ decline are associated with agriculture | Science