US bird populations are still crashing

Birds are facing a population crisis, but a lack of high-quality localized data has made it difficult to understand the drivers behind specific declines and to craft effective conservation responses.

Now, a team of researchers has developed an innovative solution, combining vast amounts of data from a popular birding app with machine learning and advanced statistical methods to overcome the challenges posed by large-scale citizen science projects.

Their study, published Thursday in Science, reveals that North American bird populations are being hit hardest in their traditional strongholds, as rapid environmental shifts — including climate change — disrupt these once-reliable refuges.

"We have known for a long time that bird populations are declining," lead author Alison Johnston, an ornithologist and ecological statistician at the University of St Andrews, told AFP.

"What we aimed to do here was to look at better population trends in much more detail," she said — data that is "a lot more tailored for conservation decisions and understanding what we can actually do on the ground."

A landmark 2019 paper also in Science found that North America had lost 2.9 billion breeding adult birds between 1970 and 2017 — a net loss of nearly a third. The 2025 US State of the Birds report found continued declines in nearly every ecological biome.

Birds play vital roles in ecosystems, from pollinating plants and dispersing seeds to controlling pests.

Their loss disrupts food chains, undermines forest health, reduces crop yields — and deprives people of the joy of watching species that have long been part of human culture.