Tiny songbirds such as grosbeaks and warblers migrate thousands of miles, flying at night and resting during the day, to and from their wintering grounds—and unlike many larger birds, they often forgo flocks and travel independently. But recent research suggests they’re not entirely alone in the dark sky.
Benjamin M. Van Doren, an ornithologist at the University of Illinois Urbana-Champaign, and his colleagues set up ground-based microphones at 26 sites across eastern North America and collected more than 18,300 hours of calls from birds in flight. The researchers found that solitary migrating songbirds seem to cooperate across species, possibly sharing information with other solo travelers about who they are and what to watch out for ahead. {read}