Jackdaws take ‘democratic’ vote over when to take flight

IT IS no coincidence that the collective noun for jackdaws is a clattering.

From the early hours of the morning, huge roosts of the birds will call to each other in a loudening cacophony, before taking flight in a sudden and boisterous collective getaway.

Now scientists have discovered that the clattering is a form of democratic decision-making.

When the cawing reaches a critical mass, it signals that a consensus to leave has been reached and the birds will take off in unison.

To prove the theory, scientists at the University of Exeter recorded extra jackdaw calls and played them to the birds amid their usual morning clamour. They found the flock took off an average of six and a half minutes earlier, as if they had been collectively counting the votes, waiting for sufficient agreement. The behaviour is most prevalent during the dark winter months.

“After roosting in a large group, each jackdaw will have a slightly different preference for when they want to leave, based on factors like their size and hunger,” said Alex Dibnah, who led the study as part of a masters by research at Exeter’s Penryn Campus in Cornwall. “However, it’s useful to reach a consensus. Leaving the roost together has various benefits, including safety from predators and access to information such as where to find food.

“Our study shows that by calling out jackdaws effectively ‘cast a vote’ and, when calling reaches a sufficient level, a mass departure takes place.”

Consensus decision-making is common in the animal kingdom. Whooper swans will call to each other to signal a

‘After roosting in a large group, each jackdaw will have a different preference for when they want to leave’

change of movement, while gorillas gaze in a particular direction before setting off together.

Alex Thornton, professor of cognitive evolution at Exeter, said he hoped future studies would examine how human activities may affect such types of behaviour.

“As human impacts on wildlife grow, we are very interested in understanding how human disturbance – for instance, from light and noise pollution – may affect animal groups’ abilities to communicate and reach consensus decisions,” Prof Thornton said.