Fairy-wrens learn alarm calls of other species just by listening

Birds often eavesdrop on the alarm calls of other species, making it possible for them to take advantage of many eyes looking out for danger. Now, researchers reporting in Current Biology on August 2 have found that fairy-wrens can learn those unfamiliar calls—which they liken to a foreign language—even without ever seeing the bird that made the call or the predator that provoked it. Instead, the birds in their study learned to recognize new alarm calls by listening for unfamiliar sounds within a chorus of familiar alarm calls.