Abstract

Many birds and mammals gain useful information about predators by eavesdropping on the alarm calls of other species. This raises the puzzle of how individuals recognize these calls, because alarm calls vary widely in acoustic structure among species. Recognition might be possible because alarm calls of different species share key acoustic properties, or because individuals learn to recognize other species’ calls. I consider these possibilities in our research on Australian birds, which reveals that while call structure can affect response, learning is critical in enabling individuals to tailor responses to the local community and to explain taxonomically widespread eavesdropping. Our work includes geographic comparisons and learning experiments carried out on wild birds. We show overall that individuals gain valuable information about danger from heterospecifics, and that learning–including social learning–helps individuals join the ecological “information web”.