Jackdaws（寒鸦） are the smallest member of the crow family. They often live in a crowd. Indeed, when cold weather comes, they gather in the hundreds (and sometimes thousands) every evening so that they can sleep in the same place. If you've ever heard jackdaws during their evening gatherings and morning departures, you'll know they are not quiet birds. Despite being fairly low-volume during the day, they are really loud on either side of their night-time get-togethers. Why might this be?
A team of the Cornish Jackdaw Project set out to determine why jackdaws are so noisy before they depart from their sleeping spot. The team's theory was that the morning calls might be a jackdaw version of "voting". The researchers suspected that each individual's call might count as an "I'm in!". When a certain amount of "I'm in!" s are called —and so a certain volume of noise is reached -the group might then depart as a unit.
To test this idea, the researchers artificially increased the level of calls during the jackdaws' natural morning calls. Their expectation was that, if jackdaws really are "voting with their voice" to decide when to depart the sleeping site, artificially adding calls would make them leave earlier than they naturally would have done. Subsequent experiments confirmed their expectation. The team therefore showed that jackdaws use their calls as a sort of voting system.
You might wonder why this happens. The researchers suggest that individual jackdaws benefit from the voting system because they are less at risk of being killed and they can get more access to social information — such as where to find food.
So the loud calls of jackdaws in the morning are therefore not the pure chaos it sounds like. If you are ever being driven mad by the sound in the morning, you can find comfort in the fact that the louder they get, the sooner they will leave you in peace.
