A record-breaking night of bird migration was detected on September 25, 2025 by BirdCast, a platform that uses the same weather radar technology behind daily forecasts to track migrating birds.  

On its live migration map, BirdCast tracked more than 1.2 billion birds streaming south to their wintering grounds after sunset Thursday—the largest single-night total ever recorded since the collaborative research project began mapping live migrations in 2018. This surge surpasses the previous milestone of one billion birds, first observed in October 2023.  

BirdCast is a collaborative research project that uses weather radar and machine learning to track and forecast bird migration patterns, with research contributions from the Cornell Lab of Ornithology, Purdue University, University of Illinois Urbana-Champaign, and University of Massachusetts Amherst. 

Read the full story in the Cornell Lab of Ornithology's news room.