New Hampshire Audubon Seacoast Chapter
(originally scheduled for December 2025)
This February Program is a follow-up to our February 2021 30 Billion Birds Lost program by Ken Rosenberg of Cornell. A new expansive study of North American bird population trends was published in Science May 2025 which will be the subject of this program.
Effective bird conservation has been limited by a lack of fine-scale population data. This talk presents new analyses using data from eBird to estimate changes in abundance for 495 North American bird species from 2007 to 2021 at a 27-kilometer resolution. Results reveal widespread but spatially complex declines; while 75% of species are declining overall, 97% show both increasing and decreasing trends in different areas. Strikingly, declines are often steepest where species are most abundant. These findings offer a new lens on population dynamics and provide sharper tools to guide urgent, targeted conservation efforts.
Al Stewart, Jr.