Bird Populations in North America Declining at Alarming Rate

Billions of birds have disappeared from North American skies in recent decades, and a new study reveals their populations are vanishing at an increasingly rapid pace. The primary culprits behind this accelerating decline are intensive agricultural practices and rising temperatures due to climate change, according to research published Thursday in the journal Science.

The comprehensive study examined 261 bird species and found that nearly half showed statistically significant population losses. More worryingly, over half of those declining species are experiencing accelerating losses since 1987.

“Not only are we losing birds, we are losing them faster and faster from year to year,” said study co-author Marta Jarzyna, an ecologist at Ohio State University. “Except for forest birds, almost every group is doing poorly. So we need to ask ourselves a question. How do we protect these groups of birds?”

Lead author Francois Leroy, also an Ohio State ecologist, noted that while the species declining most rapidly—European starlings, American crows, grackles and house sparrows—still maintain large enough populations to avoid immediate extinction risk, their dwindling numbers are cause for serious concern.

“The decline is somehow maybe giving a preview of what it could lead to in terms of species extinction,” Leroy warned.

The new research builds upon a landmark 2019 study by Cornell University conservation scientist Kenneth Rosenberg, which found North America had lost approximately 3 billion birds since 1970. The latest study goes further by analyzing changes in the rate of decline and identifying potential causes.

Rosenberg, not involved in the current research, pointed out that the rapid decline of adaptable species should raise alarm bells. “If our environment cannot support healthy populations of these extreme generalists and extremely adaptable species that are tolerant of humans, then that is a very strong indicator that the environment is also toxic to humans and all other life.”

Geographically, the most significant accelerations in bird population losses were documented in the Mid-Atlantic states, the Midwest, and California. When researchers examined the data more closely, they found a clear correlation between temperature increases due to human-caused climate change and bird population declines, with more substantial losses occurring in southern regions where temperatures have risen most dramatically.

“In regions where temperatures increase the most, we are seeing strongest declines in populations,” Jarzyna explained. “On the other hand, the acceleration of those declines, that’s mostly driven by agricultural practices.”

The researchers identified statistical correlations between faster decline rates and intensive farming practices, including high fertilizer use, high pesticide use, and expansion of cropland. While they couldn’t definitively establish causation, the findings strongly suggest that modern agricultural methods play a significant role in accelerating bird losses.

“The stronger the agriculture, the faster we will lose birds,” Leroy said.

The study also highlighted a troubling interaction between climate change and agricultural intensification, with bird populations declining most rapidly in areas where both factors are present.

McGill University wildlife biologist David Bird, who wasn’t involved in the research, pointed to several aspects of modern farming that negatively impact bird populations. As human populations grow, agricultural practices intensify, more habitat is converted to cropland, machinery destroys nests and eggs, and monoculture plantings offer fewer opportunities for birds to find food and nesting sites.

“The biggest impact of agricultural intensity though is our war on insects,” Bird noted. “Numerous recent studies have shown that insect populations in many places throughout the world, including the U.S., have crashed by well over 40 percent. Many of the birds in this new study showing population declines depend heavily on insects for food.”

Richard Gregory, head of monitoring conservation science at University College London, described the findings as both “alarming” and “sobering” due to the magnitude of losses and the patterns of accelerating decline.

The research underscores the urgent need for changes in human behavior to reduce carbon emissions and transform agricultural practices away from monoculture crops and broad application of chemicals, according to Cornell University ornithologist Andrew Farnsworth.

The stakes extend beyond just preserving biodiversity. “Birds do a lot for humans,” Bird emphasized. “They feed us, clothe us, eat pests, pollinate our plants and crops, and warn us about impending environmental disasters. With their songs, colors, and variety, birds enrich our lives… and recent studies show that their immediate presence actually increases our well-being and happiness and can even prolong our lives! To me, a world without birds is simply unfathomable.”