North American Bird Populations in Rapid Decline

North American bird populations are shrinking at an accelerating rate, driven by the combined pressures of intensive agriculture and rising temperatures, according to a new study published in the journal Science. The findings raise concerns not only for biodiversity but likewise for the health of ecosystems and the well-being of humans.

Dramatic Declines Across Species

The study, which analyzed data from the Breeding Bird Survey (BBS) collected between 1987 and 2021, examined 261 bird species across 1,033 survey routes. Nearly half of the species studied exhibited statistically significant population losses. More than half of those declining species are experiencing an acceleration in their rate of decline since 1987.

Ecologist Marta Jarzyna of Ohio State University notes, “Not only are we losing birds, we are losing them faster and faster year after year.” The declines are widespread, affecting almost every bird group except for forest birds.

Regional Hotspots of Decline

The southeastern United States is particularly affected, with losses increasing year over year. States already experiencing high temperatures, such as Florida and Texas, are showing the most pronounced declines in bird abundance.

The Mid-Atlantic, Midwest, and California are also identified as areas where bird populations are declining at an accelerated rate.

The Role of Agriculture and Climate Change

Although warming temperatures contribute to habitat degradation and shifts in bird distribution, the study highlights intensive agriculture as the strongest predictor of accelerating population declines. The more intense the agriculture – characterized by the extensive leverage of fertilizers, pesticides, and large-scale land conversion – the faster bird populations are dwindling.

François Leroy, lead author of the study and an ecologist at Ohio State University, explains, “Agriculture in general influences the acceleration of losses…The more intense agriculture is, the faster we will lose birds.” This effect is amplified in regions already experiencing significant climate warming.

Impact on Common Species

The study notes that species such as the European starling, American crow, grackle, and house sparrow are experiencing accelerated declines, even though their overall populations remain relatively large. Lead author Leroy warns that a decline in abundance can be a precursor to future extinction risks.

Broader Ecological Implications

Experts emphasize the critical role birds play in ecosystem health and human well-being. Birds contribute to pollination, pest control, seed dispersal, and serve as indicators of environmental quality.

As conservation scientist Kenneth Rosenberg of Cornell University points out, even “birds considered pests or garbage” serve as indicators of a toxic environment for all life.

Mitigation Strategies

Experts propose that reversing this trend requires significant changes in human activity, including reducing greenhouse gas emissions, lessening agricultural intensity, diversifying crops, and minimizing the use of chemicals.