Since the 1970s, the U.S. has lost billions of birds. We now know that those losses aren’t just growing – they are accelerating in places with intensive human activity, particularly where agriculture and expanding communities are changing the landscape.Bird population declines have been closely linked to pollution, use of chemicals and physical changes to their habitats.But human pressures on nature are not just continuing; they are increasing at an accelerating rate. Indicators of human activity, such as population growth, economic growth and transportation use, rose more rapidly after the 1950s, as did measures of environmental change, from atmospheric carbon dioxide levels to tropical forest loss.AdvertisementAdvertisementIn a new study published in the journal Science, my colleagues and I found that bird populations are responding in the same way: Their declines are speeding up, particularly in regions dominated by intensive agriculture.It’s not just that there are fewer birds each year. In some places, each year brings larger losses than the one before.Where bird populations are shrinking fasterUsing data from the North American Breeding Bird Survey, we analyzed bird population changes for 261 species across the contiguous U.S. between 1987 and 2021.We found that, on average, bird numbers declined by about 15% – for every six birds in 1987, there were only five three decades later. Nearly half of the species we examined showed significant population declines, with the strongest declines observed for the common grackle, the European starling and the red-winged blackbird.The North American Breeding Bird Survey is one of the longest-running wildlife monitoring programs in the world. Since 1969, trained volunteers have counted birds along thousands of fixed routes across the U.S. and Canada during the breeding season, when birds are reproducing, nesting, laying eggs or raising young.AdvertisementAdvertisementBecause the survey spans decades, a continent and hundreds of species, it provides an unparalleled window into how bird populations are changing over time.Most studies using this data focus on whether populations are increasing or decreasing. In our study, we asked a different question: Are those trends themselves sp …
