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How Big Is A Chicken Brain

If you ever hear the term “bird brain” or the other expression ‘running like a chicken with its head cut off,’ you may wonder, how large is the chicken brain?  While chickens have a reputation for being stupid, they have much more going on inside their heads than meets the eye.

Over thousands of years of domestication and selective breeding, people have changed the size of chickens’ brains and traits.  Inside the chicken’s tiny head, many things are happening that are hard to believe. Yet, chickens actually have very complex brains. Anyone who has raised chickens will know they appear stupid, yet they are far from this.

In our guide, you can learn more about the chicken brain size and the chicken without its head.  By the end, you’ll better understand that the common backyard chicken isn’t as dumb as you might like to think. (Read Can Ducks Eat Dog Food)

Chicken Brain Size

Understanding Chicken Brains

Like all birds, the success of chickens’ survival depends on their brains. While the size of a chicken’s brain is around 21 to 42 times smaller than that of a human, chickens are intelligent birds. Despite its small size, the chicken organ is a complex organ vital to coordinating the rest of the body. It is in the back of the chicken’s head and comprising two halves, just like a human brain.

Contrary to the saying “running around like a headless chicken,” a chicken’s brain is not a small, unimportant organ. Chickens use their brains to take in information from their senses, make choices, and find their way around.

Their fascinating brain anatomy is set up to let them understand visual cues and find food quickly.

Where is a Chicken’s Brain Located?

Looking at a chickens head, it’s safe to say that chickens have brains, although a chicken’s brain is quite small, only about the size of a walnut. It makes up less than 0.03% of the chicken’s entire body weight. A chicken’s brain is located at the back of its skull, right behind its eyes. This placement protects the brain from jarring movements of the head.

Chickens have monocular vision, meaning they use each eye separately. They can look for food with one eye while scanning for predators with the other. Their brain integrates the visual information from both eyes into a panoramic view of their surroundings.

Can a Chicken Live Without A Head?

You may hear stories about chickens running around without a head. So, does it matter whether or not chickens have heads to survive? Chickens might survive for a short time without their heads! The brain stem that controls vital functions like breathing is located at the back of their head. Mike the Chicken being the most famous example of chicken who lived with no head.

When a chicken’s head is cut off, the brain stem stays connected to the body. The most famous was Mike the Headless Chicken, who lived for 18 months without a head in the 1940s and named when farmer Lloyd Olsen was butchering a chicken.

Vital parts of his brain responsible for essential life-sustaining functions stayed intact even though the brain is disconnected from the rest of his body. However, if you have a chicken with an injury on top of the head and the brain gets damaged, a common chicken may not survive. (Read Can Chickens Eat Coconut)

Understanding Chicken Brains

How Does Selective Breeding Impact Chicken Brains?

Through thousands of years of domestication and due to selective breeding, backyard chickens have been adapted for specific purposes. Laying hens bred to produce eggs develop bigger ovaries, not bigger brains. Meat chickens bred for rapid growth have larger breast muscles than enhanced intelligence.

These selective pressures have likely reduced chicken brain size and abilities. But even commercial chickens retain an impressive capacity for complex behaviors when allowed to live in enriched environments.

Are Chickens as Dumb as Their Reputation Suggests?

While a chicken’s brain is small, it should not be underestimated. Chickens have wonderful memories, complex social lives, and surprising abilities to adapt to challenges. They are far from mindless creatures pecking around without a thought.

Next time someone calls you a “bird brain,” remember that chickens have small but sophisticated brains enabling behaviors beyond expected for their size.

How Chickens See the World

A unique visual system in chickens enables them to have a 360-degree view of their surroundings, even with a head as tiny as theirs. Chickens rely on monocular vision, unlike human binocular vision, which means chickens can recognize depth and distance. They use each eye separately to look for food and threats.

The chicken’s brain works well to handle visual information, which helps it see things clearly. Chickens are also able to recognize more colors than humans. (Read Can Chickens Eat Figs)

Chicken Brain Anatomy

Given its small size, the makeup of a chicken’s brain is very interesting. Even though chickens’ brains are smaller than humans, they are well-equipped to do what they must to stay alive. Like human brains, a chicken brain consists of two halves or hemispheres. Each half of the bran handles different functions and actions.

  • The chicken’s brain left side processes social knowledge. Chickens also talk to other chickens, and recognizing members of the flock.
  • The right side handles spatial processing and recognition, including potential food sources.

Hens can look around their surroundings using their unique brain structure to find food. If they scratch around and the object is food, the side of the brain, the foot, is one will see first. However, chickens can also use each eye to look for food in different areas. (Read Can Chickens Eat Butternut Squash)


Despite having smaller brains than human beings, chickens are among the most domesticated animals. Even though chickens may seem dumb, it comes from their brains working significantly different from ours.

Research shows that chickens are capable of empathy and much smarter than we think. Knowing more about the size of a chicken’s brain makes us like these birds more. It also shows how different animals are in how smart they are and how they survive.


How big is a chicken’s brain compared to a human’s?

The answer to this question, the chicken’s brain will be around 1/100th the size of the human brain. The average weight of a chicken brain is less than 1 ounce, while average human brain is about 3 pounds.

Where is a chicken’s brain located in its head?

A chicken’s brain is situated at the back of their skull, right behind the eyes and beak. This protects the brain from head movements while pecking and scanning for food or threats.

Can a chicken survive without its head?

Remarkably, chickens can live for a short time without their heads. Mike, the Headless Chicken, lived for 18 months after his head was cut off in the 1940s. This is because the chicken’s brain stem remains connected to the body.

Do chickens have good vision despite the small brain?

Yes, chickens have excellent vision. Each eye moves independently and transmits visual data to the brain, allowing chickens to see predators while looking for food at the same time.

Are chickens less intelligent than other birds?

Chickens have smaller brains than some birds, like crows. But when accounting for body size, chicken brains are large relative to other birds. Chickens are capable of complex cognition and behaviors.

Why did domesticated chickens evolve small brains?

Through selective breeding, chickens developed smaller brains, likely to allocate more energy to egg and meat production. Commercial strains with reduced brains also resulted from extensive inbreeding.

How Big Is A Chicken Brain