Eavesdropping on the neighbours: fledglings learn to respond to heterospecific alarm calls

► We tested at what age fledgling scrubwrens begin to recognize heterospecific alarms. ► Young just fledged responded to conspecific but not heterospecific alarm calls. Two weeks later most fledglings responded to heterospecific alarms. ► Response developed later on territories where heterospecifics were uncommon. ► Fledglings quickly learn to respond, depending on experience at tiny spatial scales.