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Songbird vocal learning has interesting behavioural and neural parallels with speech acquisition in human infants. Zebra finch males sing one unique song that they imitate from conspecific males, and both sexes learn to recognize their father's song. Although males copy the stereotyped syllable sequence of their father's song, the role of sequential information in recognition remains unclear. Here, we investigated father's song recognition after changing the serial order of syllables (switching the middle syllables, first and last syllables, or playing all syllables in inverse order). Behavioural approach and call responses of adult male and female zebra finches to their father's versus unfamiliar songs in playback tests demonstrated significant recognition of father's song with all syllable-order manipulations. We then measured behavioural responses to normal versus inversed-order father's song. In line with our first results, the subjects did not differentiate between the two. Interestingly, when males' strength of song learning was taken into account, we found a significant correlation between song imitation scores and the approach responses to the father's song. These findings suggest that syllable sequence is not essential for recognition of father's song in zebra finches, but that it does affect responsiveness of males in proportion to the strength of vocal learning. This article is part of the theme issue ‘Vocal learning in animals and humans’.

No abstract

Echolocation allows bats to orient and catch insects in the dark. One intriguing question is how bats are able to recognize their own echoes when hunting in groups. Bats can adjust their call frequency, but this strategy may not be efficient for species like Myotis daubentonii emitting broadband frequency modulated signals. However, the actual masking may be reduced for bats like M. daubentonii emitting short directional signals with low duty cycle. We used a 12-microphone array and infrared camera to record flight and vocal behavior of groups of Daubenton’s bat hunting over a river in the field. We used flight path reconstructions to analyze the acoustic world from the bat’s perspective. For the focal bat, we reconstructed (1) its own emissions, (2) the pulses from conspecifics nearby, (3) its own insect echoes, and (4) insect echoes from pulses of the other bat. The data showed that when two bats fly together echoes were only rarely overlapped by the other sounds. We here provide a framework for obtaining detailed information of flight and echolocation behavior in complex natural surroundings, emphasizing the importance of adapting a “bat’s viewpoint” when studying natural echolocation.