Weather radar watched 1.2 billion migrating birds take flight over the central portion of the U.S. the night of Oct. 6-7. It was the first billion-bird night reported by BirdCast, a migration monitoring effort made jointly by the Cornell Lab of Ornithology, Colorado State University and UMass Amherst.
The birds had been held on the ground by bad weather. The migration flight as observed began just north of Duluth, passing over Minnesota and continuing to the Gulf Coast.
Many of the birds were warblers, the report said, with large numbers of yellow-rumped and palm warblers. Those two species are known for being early to arrive in the spring and late to leave in the fall.
