All of the sulphur-crested cockatoos studied by the researchers were left-handed (Source: Eddy Knopper/stock.xchng)Parrots, like humans, choose to use one side of their body more than the other, with more of them left-handed - or, more precisely, left-footed than anything else.
Some species even try out both before deciding on one side.
Australian researchers found that virtually all the parrots they studied prefer to use either their left eye and left foot, or right eye and right foot.
"Basically, you get this very close relationship with the eye that they use to view the object and then the hand that they use to grasp it, and it's very consistent across all the species except a couple," says Dr Culum Brown, a senior lecturer at Macquarie University in Sydney, who led the study.
"In some species, they're so strongly right- or left-handed at the species level that there's effectively no variation."
In the study, published in the journal Royal Society Biology Letters, Brown and his colleagues studied roughly 320 parrots from 16 different Australian species to see which eye they used to view potential foods.
They found that roughly 47 per cent were left-handed, 33 per cent right-handed, and the remainder ambidextrous.
In some cases young birds appeared to experiment with both sides before finally settling on one.
"With sulphur-crested cockatoos - every single individual we've seen is left-handed. But when you see the juveniles which have just fledged, they're experimenting with both hands, all the time," says Brown.
"They eventually settle on using their left hands."
Lessons in multi-tasking
The idea of handedness in humans is tied to the use of one hemisphere of the brain over another, known as 'lateralisation'. In the case of the parrots, this appeared to be an advantage regardless of whether the left- or the right-side dominated.
"It's quite obvious that in terms of direct foraging, as well as more complicated problem-solving situations, that if you're very strongly lateralised, irrespective of whether you're right- or left-handed, you tend to be better at this sort of task," says Brown.
He added that lateralisation allowed much more efficiency, the way a computer with two processors can do two things simultaneously and effectively multi-task.
"We think that's possibly what's going on with parrots," he says.