Brain Size for the Birds

A new study suggests that size may not matter all that much when it comes to brains. This despite other studies that suggest that the bigger the brain, the smarter the animal (including humans). And it probably comes as no surprise to avid Science Today readers that the smaller, smarter brainpower comes from corvids—crows, ravens, and jackdaws.

“There is still so much we need to understand and learn about the relationship between intelligence and brain size, as well as the structure of a bird’s brain,” says study lead author Can Kabadayi of Lund University. “But this study clearly shows that bird brains are not simply birdbrains after all!”

A well-known 2014 study of animal brains measured self-control in several different animals—36 species tested in total, of which 23 were primates, six were other mammals, only seven were birds, and none were corvids. That study used a cylinder test, where food is placed in a transparent tube with openings on both sides. The challenge for the animal is to retrieve the food using the side openings, instead of trying to reach for it directly. To succeed, the animal has to show restraint and choose a more efficient strategy for obtaining the food. The research team concluded that great apes performed the best—and that absolute brain size appeared to be key when it comes to intelligence.

Kabadayi and his colleagues, knowing how intelligent corvids are, decided to try the cylinder test on ravens, jackdaws, and New Caledonian crows to see how they fared. The team first trained the birds to obtain a treat in an opaque tube with a hole at each end. Then they repeated the test with a transparent tube. The animal impulse would naturally be to go straight for the tube when they saw the food. However, all of the ravens chose to enter the tube from the ends in every trial—100 percent of the time! The performance of the jackdaws and the crows came very close, at 97 percent, comparable to a performance by great apes such as bonobos and gorillas.

Why is self-control an important sign of intelligence? According to the new study, “Self-control is essential to such complex cognitive skills as decision-making and planning.” And apparently, size doesn’t matter for this type of intelligence. “This shows that bird brains are quite efficient, despite having a smaller absolute brain size. As indicated by the study, there might be other factors apart from absolute brain size that are important for intelligence, such as neuronal density” and brain structure, says Kabadayi.

Makes you wonder why corvids were left out of the original study… (Doesn’t seem like the smartest decision.)

Image: Leo Reynolds/Flickr