A group of zoopsychologists examined existing knowledge about the bird brain and hypothesized the existence of basic neural properties that allow birds to remain intelligent despite their small brain size.

Complex cognitive abilities such as solving puzzles, recognizing speech, recognizing oneself in the mirror, and others are thought to require two basic features. First, it is a large brain because it has a large number of neurons and, as a result, more computing power. The second is the isocortex, the new cortex of the brain, which separates higher mammals from lower mammals. In humans, it accounts for 80% of the brain’s active volume and is responsible for thinking, speech, and other important functions. The isocortex is a transport exchange that connects different branches of the brain. This mechanism helps to remember and imagine objects better.

However, birds, like mammals, show high cognitive abilities despite the difference in brain size: in primates it can reach 400 grams, while the bird brain does not exceed 40 grams (and often from one to 25 grams). With such a small brain, New Caledonian crows (Corvus moneduloides), for example, knowing how to use tools, remembering where they left them, and providing steps to solve problems. Great yellow-crested cockatoos in Australia (Cacatua gallerita) learned to open garbage cans to search for food and spread the new skill to other populations. And pigeons (columba livia) distinguish spelling errors in short English words, but they learn more slowly than other “smart” birds.

One study compared the intelligence of parrots, non-human primates and crows. It turns out that all these animals have similar cognitive abilities and work equally well, except for spatial skills. In a new article published in the journal Trends in Cognitive ScienceThree German biopsychologists doubted that intelligence depended on brain size. Researchers have proposed four key neural traits that suggest “intelligent” birds and mammals evolved independently of each other.

The authors argue that the size of the brain is not as important as the number of neurons. A bird’s brain remains small for any body size because birds always conserve mass to avoid losing their ability to fly. Previous research has shown that birds have twice as many neurons per brain volume as primates and four times as many neurons as rodents. But apparently, as the authors note, the decisive role is played by a large part of the associative neurons that process information.

Additionally, according to the researchers, birds have an analogue of the mammalian isocortex. It consists of formations in the form of layers and columnar structures located in many sensory areas of the pallium (the cortex of these large hemispheres in mammals). Additionally, both birds and mammals have independently evolved working memory in the prefrontal region of the brain. For example, neurons in this region were active during memorization in crows.

The authors note that in the same prefrontal region, birds and mammals have a system that uses the neurotransmitter dopamine to make decisions and adapt to changing situations. Biopsychologists emphasize that these systems are not homologous, but are the results of convergent evolution.

The new explanation for the development of the intelligence of “smart birds” has a number of questions to be resolved. For example, it is not clear how birds’ long-term memory works and how they extract information from it. The authors suggest that other important factors affecting the bird’s mind are the cerebellum and high body temperature (40-42°C).