A new study found that the bird’s distinct warning call for Brown-headed Cowbirds might also benefit eavesdropping neighbors.

Now, according to research published last month in Communications Biology, it turns out another species might also benefit from these seet calls: Red-winged Blackbirds who nest near Yellow Warblers. “We’ve known about the seet call of the Yellow Warbler,” says Mark Hauber, a behavioral ecologist at the University of Illinois at Urbana-Champaign and co-author of the study. “What we didn’t know was that another species understands the seet call and considers it to be a danger to itself, too.”

Although cowbirds trick more than 200 bird species into raising their young, only Yellow Warblers produce a specific warning call that signals a cowbird’s presence. And though research has shown that several species, including nuthatches and hornbills, eavesdrop on their neighbors’ conversations to gather intel on predators or good feeding spots, this is the first report of one species recognizing another's brood parasite warning. This ability might help Red-wingeds in their own defenses against cowbirds, the researchers say.

Read full article in Audubon

Read similar article in Scientific American, "Red-Winged Blackbirds Understand Yellow Warbler Alarms"  (Podcast Transcript 4/13/2020)