Whilst in relation to their body size corvids and parrots have large brains, proportionally similar to that of monkeys and apes, the overall size remains small. For a macaw, we’re talking the size of a walnut. This small size would suggest they are less able to process information and instead live up to the old ‘bird brain’ tag, but these birds still have remarkable cognitive abilities. The intellectual ability of some birds parallels that of primates. A new study has unveiled the reason why.
Many birds, in particular corvids (the family containing crows and ravens) and parrots, are capable of cognitively demanding tasks: making and using tools, solving problems, understanding underlying mechanisms and anticipating future behaviour of others. Corvids in particular have been found to be capable of spontaneous analogical reasoning and can exhibit motor self-regulation on a par with great apes. Songbirds and parrots also possess the ability for vocal learning – parrots even exhibit the exceptional ability to learn words and use them to communicate with humans.
How do they achieve these feats? Well, information travels through the brain using neurons, and higher numbers of neurons results in a better ability to process information and thus enhances cognitive abilities. It turns out that bird brains have more neurons than a mammal with a brain of the same size. Songbirds and parrot brains contain about twice as many neurons as a primate brain of the same mass, and two to four times that of a rodent. Not only greater in number, but bird brain neurons and their connections are also more efficiently packed than that of mammals.
“In brains, nature has two parameters it can play with: the size and number of neurons and the distribution of neurons across different brain centres,” said lead author Suzana Herculano-Houzel, of the Charles University, “and in birds we find that nature has used both of them.”
The brain consists of sections; the telencephalon or forebrain is responsible for higher functioning, including movement and learning. In birds the forebrain makes up the same proportion of the brain as it does in primates. While the exact relationship between intelligence and number of neurons hasn’t been entirely established, a bird’s expanded forebrain could put it on a par with primates in higher functions, such as vocal learning and other adaptable, innovative behaviours.
The parrot brain is unique in its structure, allowing for the development of a distinctive song system and remarkable vocal abilities. Within large-brained parrots the subpallium, a section of the forebrain, contains more neurons in comparison to large-brained songbirds. As the subpallium is important in sensory and motor learning, it is suggested that its greater number of neurons could explain the increased capacity for vocal learning that parrots demonstrate.
It appears that parrots and corvids make up for smaller overall brain sizes by packing in more neurons. This could mean that the avian brain has the potential to carry out cognitively demanding tasks, and potentially provide much higher “cognitive power” per unit mass than mammalian brains. The term ‘bird brain’ may about to be consigned to the history books.
Olkowicz, S., Kocourek, M., Lučan, R. K., Porteš, M., Fitch, W. T., Herculano-Houzel, S., & Němec, P. (2016). Birds have primate-like numbers of neurons in the forebrain. Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1517131113
Discover the story behind the research through the scientist’s eyes, subscribe to Biosphere digital magazine for access to in-depth articles that bring the natural world to life.