Scientists have discovered that jackdaws use a “democratic” procedure to decide when to depart their roosts in large groups.
In the winter, thousands of jackdaws can take to the morning skies, producing a whirling black cloud of creatures.
Researchers have discovered that when the birds wish to depart, they shout out.
The birds fly away when the noise reaches a crucial level, signalling that the roost is ready to depart.
The first is noise volume, and the second is a crescendo or the rate at which the noise levels rise.
Once the birds have reached an agreement, the roost of thousands of birds will launch from the tree in around five seconds, creating one of the most renowned winter UK sights.
According to the researchers, when noise levels rise rapidly, the roost leaves earlier.
Thousands of jackdaws have been seen departing trees en masse in Norfolk.
Prof. Thornton argues that jackdaws prefer to leave the trees together because it shields them from predators or allows them to “share information.”
Over two winters, scientists placed audio recorders in trees where jackdaws roost in Cornwall to study the birds’ behaviour.
The researchers, led by Master’s student Alex Dibner, analysed the sounds and matched them to when the birds departed the trees.
The scientists put their theories to the test by playing back the recordings to jackdaw roosts, who responded by leaving six minutes earlier on average.
The birds did not flee when wind noises were played instead, demonstrating that jackdaws responded to calls rather than loud disruption.
Prof. Thornton notes that other birds may behave similarly, although scientists have yet to investigate this further.
According to him, the findings would aid scientists in better understanding the impact of human activities on animal populations.
Light and noise pollution are increasingly causing disturbances to birds, which may be interfering with animals’ capacity to interact with one another.
“Think of a large roost near a city or a busy highway. It might have major ramifications for their population if the birds can’t communicate with one another and agree to migrate together,” Prof. Thornton says.