Crows use their cries to “vote” and make decisions

What if democracy wasn’t a system reserved for men? Early scientific studies suggest that animals too would put consensus at the heart of their decision-making, as the BBC has spotted . Indeed, British researchers have observed groups of jackdaws – a kind of crow – of several tens of thousands of individuals. They realized that the latter used the intensity and the rhythm of their cries to let their congeners know that they wanted to leave.

As with humans, it is once the majority is acquired that the group follows this desire to leave such a place to reach a less exposed or simply more interesting perch. So, as Professor of Cognitive Evolution at the University of Exeter Alex Thornton explains, “when a bird calls, it votes or signals that it wants to leave”. Then, the decision taken by the group depends on several parameters: the volume of the noise that the group makes as well as the speed with which the noise level increases. Once this has reached a sufficient level, the individuals leave their perch in just a few seconds. If the noise level increases faster, the group leaves earlier.

These observations could be due to chance, but this is not the case. Indeed, the scientists then had fun broadcasting the recordings made during their observations when gigantic groups were placed in a tree. Verdict? The thousands of birds reacted the same way, leaving their perch in about six minutes. This departure is not due to noise pollution. Indeed, when wind noises were played by the scientists, the birds did not move an inch. According to the researchers, this clearly indicates that they were reacting to the content of the first recordings and not to the nuisances as such.

According to the professor from Exeter, this behavior would allow these jackdaws to protect themselves against predators. At the same time, he believes that this group flight allows individuals “to share information”. “If they fly away together , they may notice that another individual is particularly well fed,” he notes to the BBC . However, such an individual “is worth following to find a good place for a meal”, he explains.

Finally, these last observations could be all the more interesting in the fight against noise pollution in urban areas or roads. Indeed, this study could explain why cities can have a devastating effect on groups of birds. “If they can’t get along and can’t agree to leave together, it can have big impacts on their population,” said Alex Thornton. For example, in France , 43 bird species have seen their population decline in recent years, according to counts made by the Stoc program (temporal monitoring of common birds) since 1989.

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