Jackdaws so loud in morning because they’re deciding when to fly off together, study claims

The departure time is closely linked to the intensity of the birds’ calls, researchers said

A group of jackdaws is known as a ‘clattering’ (Getty/iStock)

Jackdaws make so much noise in the morning because they are trying to reach an agreement on when to fly off together, according to a new study.

A group of the black birds is known as a “clattering” due to their cacophony of squeaky high-pitched calls. They tend to live in large groups, normally spread across a number of trees in the same area – but can also be found nesting in chimneys.

Jackdaws are part of the highly-intelligent corvid family of birds, which includes crows, ravens, and magpies. Jackdaws are distinguished by their smaller size and lighter plumage on their heads, and are known to pair up for life.

But they benefit from living in large groups as their vast numbers reduce their individual risk of falling victim to predators, and enable them to exchange information about where food can be found.

Ravens, which can be found at the Tower of London (as pictured), are related to jackdaws (Getty)

When they want to fly to another place, jackdaws have a democratic process of deciding when to leave, the scientists said, which is necessary as the birds’ various ages and family groups render them unlikely to want to fly away at the same time.

During the winter, University of Exeter researchers filmed the birds in Cornwall at six jackdaw roosts that varied in size from 150 to 1,500 birds.

The team measured the intensity of the birds’ calls leading up to the point they took flight, and right after. The researchers found that the timing of departure is closely linked to how intensely the birds called out to each other.

On some mornings, the birds left in a succession of small groups over about 20 minutes. Most of the time they set out in mass departures, with hundreds of birds taking off within about four seconds of each other.

It was often found that calling intensity increased over the hour before the biggest group take-off. The team concluded that changes in calling intensity could enable the birds to synchronise their daily departures.

To confirm their findings, the researchers played the sounds of jackdaw calls to the birds to see if they could get them to take off quicker than they usually would have done. They found that they could get them to leave six and a half minutes earlier on average.

The consensus among the birds is achieved as the intensity of calls build to a point that triggers them to act, the researchers’ observations suggest.

On the few occasions when the intensity of the calls did not build up sufficiently, the birds appeared to have failed to reach an agreement and instead took off in “dribs and drabs” rather than all at once.

Professor Alex Thornton, the author of the study, said: “Like humans, large animal groups can use decision-making processes to overcome their individual differences and reach a kind of ‘democratic’ consensus.

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

The findings were published in the journal Current Biology.