Bird brain? Study shows avian brains packed with neurons

WASHINGTON – Scientists have long been baffled by the smarts displayed by some birds with tiny brains. But a new explanation may turn the term "bird brain" on its head: Birds have more densely packed neurons in their brains than other animals, contributing to cognitive ability on par with that of primates, researchers said on Monday. A macaw's brain may be the size of a shelled walnut, far smaller than that of a macaque monkey -- which has a brain the size of a lemon -- but the parrot has many more neurons, or brain nerve cells, in its forebrain, a region crucial for intelligence, according to a study published in the Proceedings of the National Academy of Sciences. The researchers were the first to systematically measure neurons in the brains of 20 bird species ranging in size from the tiny finch to the six-foot (1.8-meter) emu. "For a long time having a'bird brain' was considered to be a bad thing," said senior author Suzana Herculano-Houzel, a neuroscientist at Vanderbilt University.