Jackdaws use a democratic process before taking off en mass - study

Research shows that the birds tend to call to each other before taking off together, and the calls function as votes for when to leave.

 A jackdaw grabs a piece of bread thrown by tourists, as Monte Rosa, Castor and Pollux mountains are seen in the background at the Gornergrat in Zermatt September 28, 2010.  (photo credit: REUTERS/DENIS BALIBOUSE)
A jackdaw grabs a piece of bread thrown by tourists, as Monte Rosa, Castor and Pollux mountains are seen in the background at the Gornergrat in Zermatt September 28, 2010.
(photo credit: REUTERS/DENIS BALIBOUSE)

Research shows that jackdaws use a democratic process when leaving their roosts together.

In winter, the crow variety roosts in groups of hundreds or thousands, and they commonly take off all at once at sunrise.

The peer-reviewed study, which was led by a team of researchers from the University of Exeter, recorded the rackets of jackdaws at various roosts in Cornwall before they take off as well as using pre-recorded jackdaw calls at a colony.

These tests revealed to the scientists that the jackdaws use a consensus when making decisions just like in a democratic process.

"After roosting in a large group at night, each jackdaw will have a slightly different preference about when they want to leave, based on factors like their size and hunger," said Alex Dibnah, who led the study as part of a master's program at Exeter's Penryn Campus in Cornwall.

Birds (credit: FLICKR)Birds (credit: FLICKR)

Leaving the roost together has various benefits, including safety from predators and access to information such as where to find food.

Alex Dibnah, study leader

"Our study shows that by calling-out jackdaws effectively 'cast a vote' and, when calling reaches a sufficient level, a mass departure takes place," Dibnah said.

Other discoveries

Other discoveries included that mass departures happened within five seconds, usually between 45 minutes before sunrise and 15 minutes after with possible rain-related delays; the rising intensity of calling meant the birds would depart earlier; and playing recordings brought the time of departure forward by an average of six minutes.