It seems that there’s order in the apparent chaos of birdsong. A new study shows that crows can turn their calls on and off at will, rather than just involuntarily reacting to events going on around them.
Songbirds such as the crows are well known for their elaborate songs, which they use to attract mates, defend territory, recognise other birds, and a whole host of other social functions.
However, it wasn’t known whether songbirds deliberately control their calls, or whether they are simply reacting in an emotional, ‘knee-jerk’ way to changes in their surroundings, such as mates, predators, or the presence of food.
Dr Katharina Brecht and colleagues at the University of Tübingen in Germany investigated this by training three male crows to emit calls in response to a visual ‘go cue’ (a blue square) and to withhold their calls in response to another cue (white square).
In a second experiment, two of the crows were trained on a similar task with the colours of the squares reversed, as well as being trained to withhold their calls to another ‘nogo’ cue (turquoise square).
The researchers found that the crows produced precise and reliable calls in the go trials, and that they quickly learnt to suppress their calls in the nogo trials.
“Our study shows that crows can be thought to control their vocalisations, just like primates can, and that their vocalisations are not just a reflexive response,” said the authors. “This finding not only demonstrates once again the cognitive sophistication of the birds of the crow family. It also advances our understanding of the evolution of vocal control.”