The recognition of food-provisioning parents is crucial for fledglings of many bird species. Vocalisations are the most commonly used cues in parent/offspring communication and it is well established that fledglings respond specifically to their parents’ contact calls. However, fledglings occasionally also react to unrelated adults. Such responses may reflect recognition errors and be related to the similarity in individual signatures among contact calls. In a playback experiment we tested whether zebra finch fledglings perceive variation in call signatures to recognize their parents individually, and whether recognition errors, i.e. the response to unrelated individuals, are related to signal properties of male and female calls? We demonstrate that fledglings are able to individually discriminate between their mother and father and reacted more and stronger to unrelated females compared to unrelated males. Male calls are learnt and show high intra-sexual variation, thereby facilitating the accurate recognition of the father’s individual signature. In contrast, contact calls of adult females are innate, show low intra-sexual variation and the mother’s call is more likely to be confused with another female call. These findings demonstrate the importance of variation in identity signals for individual recognition processes in parent/offspring communication and highlight the importance of recognition errors for understanding the costs and benefits of individual signatures.