Participants in the Cornell Lab of Ornithology's annual Project FeederWatch are reporting large numbers of finches normally seen farther north in Canada.
Project leaders say common redpolls, sparrow-size birds with a red cap and rosy vest, typically drop into the U.S. when food is scarce up north. This winter, they're being reported across the country, with more reported in Colorado than any year since FeederWatch began in 1989.
Such an invasion is known as an irruption.
From the Great Lakes to southern Florida, watchers are reporting pine siskins and red-breasted nuthatches. FeederWatchers in the Northeast are reporting more evening grosbeaks than usual.
The project lasts through early April and new participants can still sign up at www.FeederWatch.org