Overview
- Nearly half of the 261 species analyzed showed significant declines, and more than half of those are losing numbers at a faster rate since 1987.
- Researchers used Breeding Bird Survey data from 1987–2021 across 1,033 routes and 10 habitats, finding an average 15% drop in birds per route by 2017.
- Warming was most strongly associated with overall abundance declines, with the steepest losses in already hot southern states such as Florida and Texas.
- Agricultural intensity emerged as the strongest predictor of accelerating declines, with acceleration hotspots in the Mid-Atlantic, the Midwest and California.
- Scientists emphasize the results show correlations rather than proven causation and urge safer farming practices, habitat diversification, reduced chemical use and stronger climate action.