Parrots have lateralized brains too
Cockatoos tended to be the brightest - © Dorothy Schwarz
According to recent research, it would appear that the division of labour in the brain, known as cerebral lateralization, is not unique to humans, and that in many animals, including parrots, the two sides of the brain are also responsible for different tasks.
Writing in Science NOW, Constance Holden says that a leading theory suggests that this attribute leads to faster, more accurate problem-solving, and that research on parrots shows that this separation increases brainpower. Parrots with strongly lateralised brains showed enhanced discrimination abilities and a greater capacity to solve complex problems.
Among birds, parrots and crows are renowned for their intelligence, so behavioral ecologist, Culum Brown, and biologist, Maria Magat, of Macquarie University in Sydney, Australia, tested 40 parrots from eight different Australian species.
Just as right-handedness indicates left-brain dominance in most humans, brain laterality was determined in birds by observing which eye each bird used to fixate on a piece of food, and which foot grabbed it.
The parrots were then given two tests. One involved picking out seeds from a background of similar-looking pebbles – their performance being evaluated by dividing the number of seeds consumed by the number of pecks. A more challenging task required the birds to haul up a piece of food hanging below their perch on a 50-centimeter-long string – an exercise requiring a lot of beak, foot, and eye coordination.
In the prestigious international journal, Proceedings of the Royal Society, published on 2nd September, the researchers reported that birds with stronger brain asymmetries tended to be more successful. Cockatoos tended to be the brightest and budgerigars the dimmest, but within species there was variability according to the degree of laterality. In the string test, for example, five strongly lateralized birds (one right-footed and the rest left-footed) from four species, succeeded on the first try. Birds with no lateralization performed the worst. In the pebble test they scored 55%, compared with 95% in the strongly lateralized individuals.
“These individuals have problems with coordination,” says Brown. “They try a mixture of approaches, and sometimes they manage to muddle through it.”
The authors say that the experiments show that cerebral lateralization promotes fast and accurate thinking and coordinated movements, which would increase the birds’ fitness, or ability to survive and reproduce.
Cognitive neuroscientist, Giorgio Vallortigara, of the University of Trento in Italy, who has studied the performance of chicks on the seed-pecking test, says: “The idea of a link between lateralization strength and cognitive abilities has been around … for many years, but little comparative and experimental work has been done with animals.” This study, he says, provides “fascinating confirmation of the link between higher cognition and brain asymmetry”.
