Big brains better for birds

As you might guess, big-brained birds survive better in the wild than those less cerebral for their size. Scientists guessed that too, but they had to prove it to themselves.

"The supposition that large brains are associated with reduced death rates has not been tested in any group of animals," notes Tamás Székely, a visiting fellow at Harvard's Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology.

Big brains have their disadvantages, biologists admit. They exact a high cost from their owners in the form of development time and upkeep demands. Evolution would eliminate them if they did not provide benefits to offset that cost. The benefit is obvious when you see a large-brained red-tail hawk capture a small-brained pigeon for its lunch.

However, big brains, in this case, refer not just to large brains in large animals, but to brains that are large relative to body size. According to Louis Lefebvre of McGill University in Montreal, some cockatoos with a body weight of one pound carry brains that weigh about half an ounce. Contrast this to partridgelike willow ptarmigans or spruce grouse that weigh about the same as cockatoos but have brains that weigh around a tenth of an ounce, or three to four times smaller than that of a cockatoo.