The Avian Brain: Structure and Functions
There’s a persistent misconception that birds have weak brains, but nothing could be further from the truth. These active creatures have impressive brains, capable of coordinating complex bodily functions, processing fine-tuned sensory information, and even supporting great memory, learning, and problem-solving abilities.
The bird brain varies in size between species, but each consists of five divisions, namely the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon. The latter two regions connect to the spinal cord, which is the other component of the central nervous system.
In this guide, we’ll take a closer look at some important regions of the avian brain and learn about their roles in bird behavior and survival.
Anatomy of a Birds Brain
Size and Proportions
Compared to us mammals, birds have relatively small brains, reaching a maximum of over 40 grams in the Emperor Penguin, a very large, flightless species. Brain size is an important indicator of intelligence, but the ratio of brain to body size is equally telling. That’s where brainy birds like corvids and parrots come out on top.
Major Brain Regions
The avian brain is a complex organ with several distinct components. Let’s take a look at a few of the better-known regions.
Cerebrum
Also known as the telencephalon, this region of the brain is responsible for higher cognitive functioning. It is relatively large and particularly well-developed in the most intelligent bird species. The cerebrum is located at the front and top of the brain.
Cerebellum
The cerebellum is the bird’s motor command system, responsible for coordinating movement and balance.
Optic Lobe
Birds have well-developed optic lobes for processing visual, auditory, and tactile information. Most of the information from the retina is transferred to a part of the lobe known as the optic tectum.
Brainstem
The brainstem is the region that connects with the spinal cord. It is important for communication with the rest of the body but also controls essential autonomic functions like heart rate and breathing.
Neuroanatomy
Neurons, or nerve cells, are the messenger cells that transport information between various parts of the brain, and in birds, they are clustered rather than layered. A high density of neurons in the regions of the brain involved in cognitive functioning is a good indication of intelligence, and here, scientists have discovered that corvids are almost a match for intelligent primates.
Brain size is an important indicator of intelligence, but the ratio of brain to body size is equally telling. That’s where brainy birds like corvids and parrots come out on top. American Crow.
Cognitive Abilities and Intelligence
Learning and Memory
The neuron-rich pallium, which is part of the telencephalon or cerebrum, is the region of the brain most associated with learning. This component is thought to perform a similar role to the human neocortex, the region of our brains with the characteristic wavy texture.
Learning requires memory, but recollection is also important for birds to find their way back to the nest or remember the location of a food store. The hippocampus is the part of the pallium associated with spatial memory. This important brain component is also linked to input from sensory organs to remember sights, sounds, smells, and sensations.
Problem-solving and Tool Use
Several birds are known to use tools, both in captive settings and even out in the wild. The New Caledonian Crow is a prime example of a species that builds and uses tools to perform tasks that are not possible using their own anatomy. Unsurprisingly, this species is known to be one of the smartest on the planet.
Tool use is a fascinating form of avian problem-solving, but there are many other examples. Psittaciformes (e.g., Parrots) and corvids (e.g., Ravens) tend to excel at problem-solving tasks, although recent research has also linked problem-solving to song-learning ability and brain size, highlighting the brainpower of talented singers like the Tufted Titmouse.
Social Intelligence
As it happens, many of the most intelligent birds also tend to live in complex social groups and have long periods of parental care, much like intelligent mammals. Maintaining relationships within the flock and understanding hierarchies and group dynamics requires cognitive abilities that are unnecessary in solitary species.
Sensory Processing and the Avian Brain
Visual Processing
Vision is the most important avian sense, so birds have well-developed eyes and brains capable of processing visual data at high speed.
Sensory information from the retina is sent to the brain via the optic nerve. It is processed in several areas of the bird brain, including the wulst (thalamofugal system) and the entopallium (tectofugal system).
Auditory Processing
Hearing is incredibly important for birds, both for vocal communication with other birds and for detecting danger and food. Multiple regions of the bird brain are involved in hearing, including the optic lobe and the dorsoventricular ridge.
Other Sensory Inputs
Birds’ brains process several types of sensory data. Sight and hearing may be their most important senses, but birds also use smell, touch, taste, and magnetoreception to interpret their environment.
Various parts of the brain correspond to these senses. The wulst, for example, is thought to be important for the bird’s built-in compass, while smell is processed via the olfactory bulbs and various regions of the brain.
Recent research has also linked problem-solving to song-learning ability and brain size, highlighting the brainpower of talented singers like the Tufted Titmouse (pictured)
The Avian Brain in Navigation and Migration
Spatial Orientation
Birds rely on their brains for spatial orientation in several key ways. Visual information is most important, but birds also use smell and even magnetic fields to plot their course. All of this sensory information is processed in the brain.
All birds need a way to orient themselves, but navigation is especially important for birds that travel long distances. Research on over 150 migratory bird species has shown that long-distance migrants have smaller brains but larger optic nerves. This may highlight the importance of vision in long-distance navigation. Migratory birds may also have a better-developed hippocampus for enhanced spatial memory.
Migratory Behaviors
Each year, thousands of bird species undergo annual migrations, sometimes taking them across continents and oceans to escape the coming winter. Migratory behaviors are partly instinctual since many birds make their first migrations alone. However, some species migrate as a family, which gives the inexperienced young birds the chance to learn and memorize the route.
Obligate migrants experience a phenomenon known as zugunruhe, an instinctual migratory restlessness each year. Their departure is triggered partly by instinct and partly by a combination of the nervous and endocrine systems, using sensory information such as changing day length processed in the retinae and the pineal gland of the diencephalon.
Neuroplasticity and Brain Development
Brain Growth
A baby bird’s brain begins as a neural tube, one end of which develops into the spinal cord and the other into the brain. Even before the egg hatches, the chick’s brain may be active enough to recognize the vocalizations of their species.
Brain development at hatching varies with species and is greatest in precocial birds that can walk and feed right away. The brains of helpless, altricial birds continue to develop as the young bird grows, ultimately becoming larger than in precocial species.
Neuroplasticity
Some birds exhibit regular seasonal changes in brain structure to support specific behaviors. For example, regions of a songbird’s brain associated with singing may expand during the warmer months when males actively sing to attract a mate or defend a territory. Similarly, seed-caching birds may develop a larger hippocampus to help them remember where their food is hidden during the winter.
Seed-caching birds may develop a larger hippocampus to help them remember where their food is hidden during the winter. Eurasian Nuthatch feeding on cedar nuts
Summary
The avian brain is a fascinating organ, capable of maintaining involuntary bodily processes, coordinating acrobatic physical actions, and even supporting some impressive displays of learning, problem-solving, and recollection.
As scientists delve deeper into the avian brain’s inner workings, we learn more and more about the cognitive functioning of our feathered friends.
One thing is clear - having a ‘bird brain’ is nothing to be ashamed of. So, the next time you see a bird going about its business, take a moment to consider the amazing capabilities of an organ small and light enough to fit within an avian’s cranium!