‘ALL IN FAVOR’: Acoustics used by members of the crow family to vote and make a group decision
Acoustic decision-making has previously been reported in a variety of species, ranging from lemurs to meerkats to bees. However, Jackdaws are one of only a few species in which this behavior has been experimentally validated.
BEKI HOOPER: If you live in Europe, northwest Africa or western Asia, it’s likely that you know of the jackdaw. They are the smallest member of the crow family, with a beautiful silver nape, a rasping ‘jack’ call and a sociable nature. You’ll rarely see a jackdaw alone. They are almost always with at least one other bird, and they are often in a crowd. Indeed, when cold weather comes, jackdaws are especially gregarious. They gather in their 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 – with the occasional ‘jack’ or ‘chatter’ call – they are obnoxiously loud on either side of their night-time get-togethers. But why might this be?..
Research led by Alex Dibnah asked exactly this: Why is it that jackdaws are quite so loud when they gather? Working with a team headed by Alex Thornton, leader of the Cornish Jackdaw Project, Dibnah set out to experimentally test why jackdaws make so much noise. Specifically, the team wanted to determine why jackdaws are so noisy in the mornings, just before the flock departs from its 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 flock might then depart as a cohesive unit. So, essentially, the team hypothesised that jackdaws use their voices to cast a vote, which then helps them coordinate their movement…
The team therefore showed that jackdaws use their calls as a sort of voting system. Jackdaws pay attention to the calls made in their flock, and initiate movement away from their sleeping spot once a certain volume is reached.
You might wonder why this happens. Why is it important for the jackdaws that they all leave together, and why has such a system evolved? The researchers suggest that individual jackdaws benefit from leaving their sleeping site with their flock because (1) they are less at risk of predation if they leave with others, (2) they get more access to social information – such as where to find food – if they leave with their flock, and (3) they can maximise their time to find food if they leave with everyone else and don’t have the bird equivalent of a lie-in.
This sort of acoustic decision-making is not unique to jackdaws. It has previously been reported in a variety of species, ranging from lemurs to meerkats to bees. Jackdaws are, however, one of only a few species in which this behaviour has been experimentally validated (i.e., a causal link has been demonstrated, not just a correlation).
The wonderfully riotous cacophony of jackdaws in the morning is therefore not the chaos it sounds like. Instead, it is a clever solution to the problem of coordinating a huge number of individuals. SOURCE…
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