Democratic decision to mass start – wissenschaft.de

“I vote to leave!” In the colonies of our native Jackdaws, apparently, in the morning there is a loud vote about when the communities of hundreds of birds should go away. This is due to the study of jackdaw calls at dawn. In addition, researchers were able to persuade the “Feathered Democrats” to start early by using the “acoustic deception”.

A small figure, silver-blue eyes and a loud voice: these are the hallmarks of our smallest native representative of corvids. Anyone who has a jackdaw (Corvus monedula) as neighbors knows that these birds, living in social groups, are extremely “chatty”. Sometimes the question really arises what they have to say to each other or are currently making up. Research has already confirmed that jackdaws convey complex information through their sounds. A current study by scientists led by Alex Dibnah of the University of Exeter shows that birds, apparently, can also literally vote.

Coordinated trips

The team focused on the typical group behavior of the Jackdaws during the winter months: After a night out in the trees, communities of sometimes more than 1,000 birds usually start their ‘work of the day’ at the same time. Not only are communities large, they also include people of all ages, genders, and subgroups. “Each jackdaw has slightly different preferences for when it wants to fly, based on factors such as their size and how hungry they are,” says Dibnah. “But finding a consensus seems wise. Because leaving the hideout together gives you various benefits, including protection against birds of prey and access to information about food sources – the researcher explains.

To investigate suspicions that some type of vote led to a collective departure, Dibnah and his colleagues recorded extensive audio and video footage during the winter months from six different Cornwall Jackdaw refuges. In this way, scientists were able to precisely document the course of the take-offs and investigate to what extent the screams in the night colonies of up to around 1,500 individuals changed before the mass take-offs.

First of all, it turned out that birds usually set off together – hundreds of individuals soared into the sky just about four seconds apart. These departures took place between 45 minutes before sunrise and 15 minutes later. Scientists have found that rain and heavy clouds tend to delay departure. As can be seen from the audio-recording ratings, there was always a significant increase in voice violence in the community before departure. This reflected that more people were “speaking”. Scientists interpreted this as an indication that the jackdaws were literally speaking to allow for a synchronized departure from the community. It was also remarkable that in the few cases where the intensity of the calls had not increased enough, the birds did not reach consensus. As a result, they flew away drop by drop, and not all at once.

Experimental “election fraud”

But until then, it was not clear what the cause and effect were, so the researchers conducted an exploratory experiment: they placed speakers in the sleeping trees of one of the jackdaw communities over which they played back call tapes in the morning. It turned out that, by artificially increasing the volume of voice, the birds crashed on average about seven minutes earlier. However, when the scientists recreated the wind noise to check, this was not the case. It was thus confirmed: “With their exhortations, jackdaws seem to effectively signal a readiness to leave and give the community the means to reach consensus so that they can lead coherent, collective exits from the perch,” the researchers write.

“There is evidence that animals, like humans, can use group decision-making to overcome individual differences and reach a kind of” democratic “consensus, said senior author Alex Thornton of the University of Exeter. He and his colleagues now want to stay true to this exciting research topic: they plan to continue listening carefully to the sneaky crow to discover more details of their complex communication system.

Source: Cell Press, University of Exeter, article: Current Biology, doi: 10.1016 / j.cub.2022.04.032

Video: A jackdaw community is forming in the association. © Dibnah et al. / Current Biology

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