What Can Your Chickens See? 👀
Thursday 22nd July
Chickens are fascinating creatures, and their eyes, even more so.
Here are some amazing facts about chickens' eyes that you may not have heard before!
Chickens Can See More Colours Than Us
Chickens are tetrachromatic. Chickens possess not only the three basic color cones that humans do (red, yellow and blue) but also an ultra-violet light (UV) cone. This allows them to differentiate between and see far more colors and shades than humans can.
Chickens Have a Third Eyelid!
Believe it or not, chickens actually have a third eyelid, on each eye! The third eyelid, called the nictitating membrane, horizontally draws across the eye which helps clean, moisten, and further protect the eyes from dirt. The nictitating membrane is transparent in appearance which means that chickens still have the ability to see, even when the third eyelid is closed.
Chickens Do Not See Well in the Dark
Yes, chickens are pretty much night blind! Chickens evolved after the dinosaur age and didn't spend millions of years as nocturnal animals like many other species, their night vision is poor due to their low light sensitivity never having developed in the retina. Their eyes have fewer rods than ours. This poor night vision makes them very vulnerable to predators.
Chicks Have Amazing Eyesight From Birth
When chicks first hatch, they surprisingly have remarkable eyesight, in fact a lot better than humans. From the minute they hatch, chicks are able to detect small items such as grains of food and even have spatial awareness. A human baby however, lacks this ability and does not develop such skills until a few months down the line.
They Can Use Each Eye Independently
Chickens are able to use each of their eyes independently, with a 300 degree field of vision (humans only have 180!), meaning that both of their eyes can focus on different tasks at the same time. This is also known as monocular vision, which amazingly already begins even before a chick’s arrival. The left eye is far sighted, and right is near sighted. This is the result of turning themselves in the egg so that the right eye is exposed to light through the shell, while the left is not, because it’s directed toward the body.
Chickens Rarely Move Their Eyeballs
Chicken eyes have a very limited range of motion and lack the ability to remain focused on an object whilst the rest of their body is moving. This is why you’ll often see chickens walking around, bobbing their heads, whilst facing onwards. It is not so much a case of chickens not being able to actually move their eyes at all, but rather their eyes cannot move quickly enough to process the image in front of them. Instead, chickens will tend to turn their heads when they want to gain better eyesight of something.
Their Eyes Have a Double Cone Structure
The retina of the eye is composed of rods and cones, the rods being to detect light-sensitive motion, and cones to see colour. As we found out earlier, chickens have more types of cones than us, hence why they are able to enter a fourth dimension of colour, which us humans can’t. A double cone retina structure means that a chicken’s eyes are more sensitive to movement. This is advantageous to chickens as it gives them a greater ability to detect motion, which is helpful when it comes to spotting a perceived threat.
Chickens Can Sense Light Through Their Pineal Gland
Light reaches chickens through either their eyes, skulls, or skin, which activates the pineal gland in the brain. The pineal gland, also sometimes referred to as ‘the third eye’, is something else that makes chicken vision oh so interesting. A pineal gland helps chickens to sense daylight, or the lack of, even if they are unable to see with their eyes. This means that even a blind chicken is able to detect lighting or seasonal change!
Chicken Eyes Make Up 10% of Their Head Mass
That’s quite a lot, considering our eyes only make up for approximately 1% of our head mass! Although it may look humorous, there’s actually a good reason behind it. Having such large eyes helps chickens to see larger and clearer images as they are produced.
Chicken Eyes Process More Images Per Second
One other major difference between our vision and the hens is the amount of visual sequences they can process per second. We can process around 25-30 images (or frames) per second while for the hens its around 150-200 images per second. Because their eyes are so sensitive, they can see tiny light fluctuations that are imperceptible to humans.
They Have the Ability to Recognise up to 100 Different Faces
They say that elephants never forget but apparently chickens don’t either! Chickens are able to recognize up to one hundred faces, be it other chickens, humans or any other species. They can also amazingly decipher between their positive and negative encounters.
Chickens possess not only the three basic color cones that humans do (red, yellow and blue) but also an ultra-violet light (UV) cone. This allows them to differentiate between and see far more colors and shades than humans can. The UV cones help them to find shiny bugs, seeds, berries and fruits easily among non-UV reflecting grass and dirt. A mother hen also uses her UV cones to sense which chicks are healthiest, since growing feathers reflect UV light. She can therefore determine which chicks are growing fastest and strongest, and devote more of her energy to them to ensure they survive, since they have a better chance over weaker chicks.
Just before hatching, a chick turns in the shell so its right eye is next to the shell (and absorbs light through the shell) and its left eye is covered by its body. As a result the right eye develops near-sightedness to allow a chicken to search for food, while the left eye develops far-sightedness, to allow a chicken to search for predators from afar. That is why when a hawk flies overhead, you will notice your chickens tilt their heads with their left eye to the sky.