Intelligence is a trait humans often attribute exclusively to themselves. Yet as the field of animal neuroscience advances, researchers have documented an increasingly large number of species across the animal kingdom displaying ingenuity, problem-solving, and emotional depth on a level far greater than previously realized. One particularly remarkable class of diverse and intelligent organisms stands out across these studies: birds.

Birds are a common sight in everyday life: in water, on land, and soaring above in the sky. Their prevalence stems from their extreme diversity, as they are the most speciose class of terrestrial vertebrates. Birds live in a variety of habitats and display extreme variation in lifestyle and behavior. Despite their diversity, birds share common anatomical traits. They are characterized by their feathers, which range in size, color, and morphology; toothless beaks, which are highly adapted to their food sources; and hard-shelled eggs they lay that contain their young. Though they are warm-blooded, birds are more closely related to reptiles than mammals. 

Above: A chart of the diversity of birds found in the world. Image courtesy of Animals Fandom.

Historical misconceptions of bird intelligence

Humans have long been fascinated with birds. Historically, mythology and folklore have often featured bird species—feathers, in particular, remain symbolically and aesthetically important in many cultures today. Several bird species, like parakeets and cockatiels, are also kept as cherished pets. From a scientific perspective, ornithologists have spent countless hours and resources documenting bird morphology and habitats. Some birds, like the zebra finch, are important model organisms for biomedical research. Though bird ecology and behavior have been heavily studied, their intelligence is not well understood: researchers once even believed birds had low intelligence. This misconception was based on incorrect ideas about these winged creatures’ brain structure and development due to their small size. 

Birds have small brains, especially compared to other highly intelligent animals, such as primates. However, some scientists suggested that absolute brain size is not a representative measure of intelligence, as the brain regulates essential body functions like heartbeat and breathing alongside cognitive functions. Therefore, brain size depends on the body size of the animal. Instead, researchers proposed that measures like relative brain size and the ratio of the size of the brain to the body were more relevant to intellectual abilities. When body size was taken into account, scientists found that the ratio of brain to body size of some birds was equal to that of primates. In fact, some birds have brains much larger than predicted for their body size.

The second misconception comes from the assumption that much of the bird cerebrum is derived from the basal ganglia. The basal ganglia is a brain structure critical for behaviors like maternal care, sexual behavior, and feeding, which are species-specific and largely instinctual. This misconception previously caused researchers to conclude that birds were incapable of intelligent, complex behavior. Later research proved this incorrect: it is now known that the bird cerebrum is derived from the pallium, much like the mammal neocortex. Additionally, some bird species, like corvids and parrots, have tightly packed neurons in their brains, allowing for a greater density of neurons in a smaller space. Resultantly, scientists postulated that certain avian brains evolved to navigate social situations and adapt to harsh, ever-changing environments, leading to an increased interest in the social capabilities of these creatures.

Corvids: An iconic example of avian intelligence

For those familiar with avian species, corvids stand out as a highly intelligent group of birds, and for good reason. Corvidae is a family of around 120 species, including crows, jays, and magpies, that are found all over the world. They are highly social, often living in large, highly organized flocks, and form lasting mating bonds. Despite their loud, harsh-sounding calls, corvids are classified as the largest of songbirds, as they have a well-developed vocal organ. 

Above: Illustrations of several corvid species. Image courtesy of BioExplorer.

Corvids are widely renowned for their exceptional problem-solving skills. These range from fashioning tools to help forage for food and dropping hard-shelled nuts onto roads for cars to break to complex, multi-step puzzles that involve combining tools in novel ways and future-planning to solve. Researchers have also documented instances of corvids working together to obtain a food reward. In fact, in one 2015 study, not only did ravens work together to raise a platform containing cheese, but they also ostracized those who were uncooperative! 

Aside from problem solving, corvids also display abstract cognitive abilities. For instance, they can recognize themselves in mirrors, a trait shared with primates, cetaceans, and elephants. Moreover, corvids exhibit self-control and can delay gratification for a later, better reward, passing the same test used on human children to study the same phenomenon. Similarly, corvids seem to understand the concept of different values, as they can barter and trade with others, including humans, for better items by giving them items of higher value in return. In several instances, these birds learn to differentiate which humans will offer better trades versus those that may seek to harm them. Corvids have natural curiosity and playfulness, grabbing scientific equipment and flying off with it in laboratory settings. 

These birds also show signs of high emotional intelligence. When a magpie dies, other magpies gather around and perform what seems to be a mourning ritual, where they lay wreaths of grass around the corpse. 

Above: A crow investigating a puzzle. Image courtesy of BBC.

Scientists have developed several hypotheses to explain the evolution of corvid intelligence and associated behaviors. Some suggest the long childhoods and strong social bonds of corvids, rare strategies in the animal kingdom, contribute to their strong cognitive abilities, much like in humans. Others state that the varied, often challenging environments in which corvids live lead to the need for fast adaptability and flexibility for survival; the researchers believe that curiosity and exploration help keep the mind sharp and innovative. Some experts point out that corvids seem to learn how to avoid dangers from their mourning rituals. In a 2015 study, crows took more time to approach geographical areas and learned about new predators, like hawks, that were associated with dead crows. 

These examples of corvid behaviors demonstrate the astounding cognitive abilities of these birds. We may not have uncovered the true limits of their intelligence, as new studies continue to push the extent to which corvids can exercise their mental capabilities.

Parrots: charismatic paradigms of avian cognition

Like corvids, parrots are another iconic example of birds with astounding levels of intelligence. Popular pets since ancient times, parrots belong to the order Psittaciformes (which also includes cockatoos) and are perhaps most well known for their colorful plumage and ability to mimic a variety of sounds, including human speech.

Above: illustrations of a selection of parrots. Image courtesy of RevivalPortal.

One of the most notable studies in parrot intelligence focused on Alex, an African gray parrot. Alex, trained and studied by Dr. Irene Pepperberg at the University of Arizona for over 30 years, could recognize and name 100 different objects, as well as communicate and use language with intention with his trainers. Dr. Pepperberg’s lab also kept other birds, which they discovered learned English faster from Alex than the people there, demonstrating an ability to learn from each other and copy other birds. The discoveries pioneered much of avian intelligence research and cast parrots in a new light, transforming them from simply entertaining pets to complex birds with impressive cognitive abilities.

Above: Alex, the African Gray Parrot. Image courtesy of The Alex Foundation.

Like corvids, parrots are capable of problem-solving and have long memories. Perhaps most iconic is their linguistic ability—different flocks even have different dialects. Like in humans, these dialects shift and change over time as different populations separate or mingle. Some researchers postulate these linguistic shifts reflect cultural shifts, especially in response to habitat threats, where different flocks start banding together for an increased chance of survival.

Given the advanced cognition of corvids and parrots, researchers were curious about their brain morphology. Results from these studies have been surprising: while some aspects of corvid and parrot brains are shared with humans and other primates, such as heightened connectivity between brain regions, there were also striking differences. For example, the pontine nuclei structures, which connect the cerebrum and cerebellum, were very small in birds and much larger in primates; instead, birds exhibited a large medial spiriform nucleus, which seemed to serve the same function. Thus, studying the brains of intelligent birds provides fascinating insights into the convergent evolution of intelligence, not just between birds and primates, but with respect to other animals as well.

Above: A simplified diagram of primates versus bird brain structure. Image courtesy of Forbes.

Other examples of avian intelligence

Though corvids and parrots are the clearest examples of birds with high cognitive ability, other birds have been found to possess cognitive traits far greater than previously thought. For instance, some birds of prey, like the striated caracara, show remarkable problem-solving abilities that sometimes exceed those of Psittaciformes like cockatoos. And like corvids and parrots, striated caracaras exhibit curiosity. Researchers suggest this cognition results from the harsh environments striated caracaras inhabit. Isolated on the Falkland Islands near the southern tip of South America, these birds often face grueling winters with little food, necessitating creativity to survive.

Above: A striated caracara. Image courtesy of Warren Photographic.

Surprisingly, cognition tests on pigeons and chickens show they perform better than expected. Studies have found that pigeons can count and possess incredible memories and visual abilities. Some birds have even differentiated Monet from Picasso paintings and malignant from benign tumors in radiology images. Moreover, chickens produce distinct alarm calls for different predators and also reinforce a social order within their flocks. Additionally, males only emit alarm calls in the presence of females and stay silent amidst rival males, while females only call if they have chicks. These clear signs of intelligence raise ethical concerns and call for reevaluation about how chickens are treated at farms and in coops—as well as their public image as an expendable farm animal.

A bright future for bird brains

The field of avian intelligence has majorly progressed, with scientists now recognizing species like corvids and parrots as some of the most intelligent in the world. These pivotal studies provide new avenues for researchers to continue investigating the origins and evolution of cognition in different animal lineages.