Ravens at least as smart as chimps, tiny heads notwithstanding

New research has shown that ravens are just as smart as chimpanzees, indicating that brain size has little to do with intelligence.

Raven perched on a branch in Finland.
Peter van der Veen / in Stock/Corbis

If ever there comes a great avian uprising, it's going to come from the corvids. Crows and ravens can solve complex puzzles, engineer tools, understand cause and effect, conduct funerals for their dead, recognise humans and even use social ostracism to punish birds that aren't team players.

These are birds that have some crazy smarts going on in their tiny heads. In fact, as a new study published in Royal Society Open Science has found, raven intelligence is on a par with that of chimpanzees.

The tininess of their heads, therefore, should not be used as a gauge for intelligence. Rather, neuron density and brain structure are far more relevant,

"Absolute brain size is not the whole story," said Can Kabadayi, a doctoral student in cognitive science at Sweden's Lund University, in a statement. "We found that corvid birds performed as well as great apes, despite having much smaller brains."

A previous 2014 study had tested 36 animal species to ascertain whether they were capable of suppressing their instincts to approach a problem rationally. A food treat was placed in an opaque plastic tube, with openings on both sides, and the animal was shown how to access it. A food treat was then placed in a clear clear plastic tube with openings on both sides. The instinct would be to go for the food through the clear side of the tube; a more rational approach would be to reach the food through one of the openings. Great apes were the best at performing this task.

However, no corvids were included in this study, so Kabadayi decided to see how they measured up. With the help of researchers at the UK's University of Oxford and Germany's Max Planck Institute for Ornithology, he conducted the exact same food cylinder test on ravens, jackdaws and crows.

Ravens were excellent at this task. They all went through the openings of the tube at every try, a success rate of 100 percent. Crows and jackdaws were only a little slower, with a success rate of nearly 100 percent, on a par with gorillas and bonobos.

In fact, crows can figure out cause-and-effect puzzles faster than children. That's an impressive level of calculation.

"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," Kabadayi said.

"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, but this study clearly shows that bird brains are not simply birdbrains after all!"