Chews democratically decides to fly away

Democracy in the animal kingdom is not just for humans. Chewing also appears to ‘tune’ in certain situations, British biologists discovered. Groups of hundreds of birds only fly away from their resting place when enough individuals agree.

The researchers observed this behavior when chewing in England. These small corvettes, which are also common in the Netherlands, are known as social animals. In winter, they often move in large groups, sometimes consisting of more than a thousand individuals. They spend the night close to each other in a series of treetops. At dawn, the jackets make themselves heard, after which they often suddenly fly away at once.

It is not so surprising that the animals jointly choose the airspace. Like a swarm, they are better protected from predators and can search for food more efficiently. The question is how the birds coordinate the departure time so precisely. Although this always takes place around sunrise, the exact moment varies from day to day. Yet the hundreds of jackdaws all manage to lighten up within seconds of each other.

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They are not controlled by visual signals, the researchers suspected: It is often still quite dark when they walk, and the branches block part of the birds’ view. The noise they make before departure is more likely to play a role. But how exactly? For example, do jackdaws respond to scratches from one authoritarian bird or group of leaders?

Jackdaws in a tree Photo: Jolle Jolles

To find out, the team monitored six groups of jackdaws in the English borough of Cornwall during the winter months with cameras and microphones.

Their striking discovery: the animals are acting democratically. When a jackdaw thinks it’s time to leave, let him know by making a sound. In the hour before departure, more and more chews are heard. When enough birds think the time has come and the intensity of the ‘crazy’ reaches a certain level, the group increases.

Incidentally, the jackets did not reach agreement every morning. The noise level then did not build up sufficiently, after which the birds gradually set off in small groups. The weather also seemed to influence the decision-making process: in case of a rainstorm or cloudy sky, the departure time happens later.

Election threshold

To check whether the build-up intensity actually affected the ascent moment (and not the other way around), the researchers manipulated the process. They placed sound boxes in the treetops, whereupon some days they played fragments of ‘voiced’ jackdaws. This proved to speed up the process: the group traveled on average more than six minutes earlier than on days when only the sound of wind or nothing at all sounded through the speakers. This indicates that the ‘election threshold’ is reached more quickly due to the additional votes cast.

Such democratic voting behavior, in which animals literally make themselves heard, is not unique to the animal kingdom. In the past, researchers have observed similar behavior in bees and meerkats, among others. But these cases involved relatively small groups, often consisting of one or a few families. The groups of jackdaws studied consisted of about 160 to nearly 1,500 individuals, with many unrelated animals.

“This shows that large groups of animals, like humans, can also use decision-making processes to bridge individual differences and achieve a kind of ‘democratic’ consensus,” says biologist Alex Thornton of the University of Exeter in the UK, one of the researchers, the authors .

In the future, he hopes to discover the influence of humans on this behavior. ‘We are very interested in the question of whether and how human disturbance, for example from light and sound pollution, can affect the way groups of animals communicate and make joint decisions.’

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