Do Chickens Have Full Color Vision?
How Well Can Chickens See Color and in the Dark?
Reading Time: 7 minutes
What does it feel like to be a chicken? Do they perceive the world as we do, with sound, color, and odors? Do chickens have full color vision in the way we do? It turns out they can see more color and faster movement than we can, and over a wider range, providing high-speed intel to fuel the lightening reactions they need to catch insects and avoid predators.
We can only imagine what it must be like to see ultraviolet (UV) light, explore the world with a beak, and live at such a fast pace. Chickens’ bodies and senses are very different from ours, as they are tuned to a lifestyle of foraging on the ground through thick vegetation while avoiding land and air predators. Chickens have to be smart to find hidden forage in this fast moving, perilous world. That said, their hearing covers a similar range to ours and their sense of smell is only moderate. First and foremost, their most important sense is vision, which has some truly amazing features and adaptations.
Can Chickens See Color?
Indeed, chickens see a wider range of colors (wavelengths of 350–780 nm) than humans do (380–740 nm). That means that they can see some UV light, which we are unable to see. UV sensitivity helps them to detect movement, an important skill for hunting and avoiding predators. They are more sensitive to blues and reds than we are, helping them to pick out important objects in the green of the forest. Their color sensitivity is heightened by a remarkably organized arrangement of four types of color receptors called cones (humans possess three types). Contrast is enhanced by oil droplets which act as filters, refining the ability to distinguish colors. In addition, double cones are thought to aid detection of motion.
The Importance of Full Color Vision for Chickens
Chickens are attracted to red and orange, as these colors are typical of their most treasured food sources. However, red insects are avoided as they are likely to be poisonous. They can also learn to associate different colors with palatable food, and favor shades within the range of learned colors. Other sensory features of feed are important: when feed is changed to a another type—of different color, texture, particle size, or odor—chickens may reject it until they learn the new food is palatable.
Color is important for mating and communication. Hens choose mates according to comb size and color, eye color, and spur size. Large, red crests indicate maturity, good health, and high status, so are attractive to females whilst a warning to males. Chickens’ full color vision may pick up colors in plumage that we do not notice. For example, plumage reflects UV. A fine feathered rooster may appear different to hens than he does to us. With UV in the light source, hens inspect roosters more and mating is more frequent.
Lack of UV light, such as under artificial incandescent lighting, could give poultry trouble recognizing their companions. This can cause problems with aggression. Markings may look unnaturally dull and entice feather pecking in close confinement. Fortunately, fluorescent lights contain some UV. If you are raising chicks indoors, make sure that their room is well lit (preferably with natural daylight or biolux/warm-white fluorescent light). Also, allow them at least six hours of darkness per day to enable rest. These steps ensure healthy development.
Other Visual Skills
Can Chickens See in the Dark?
Mammals, including humans, do not possess double cones, oil droplets, or UV sensitive cones. However, we can see much better in dim light than chickens. Bear in mind that chickens will struggle to see as light fades at dusk, which is why they go to roost until dawn. Very low light in indoor housing reduces activity, but can also cause development and welfare issues.
How Clearly Do Chickens See?
In fact, chickens do not see as much detail as we do at the most sensitive areas of their light-detecting organ, the retina. Humans have a very sensitive point, the fovea, where cones are concentrated and it is here that we see most clearly. There is a detailed area in the center of our vision, while the periphery is less clear.
In contrast, chickens do not have foveae. They possess similar areas of maximum clarity, although these do not distinguish detail as precisely as ours do. These sensitive areas extend upwards, to see detail of possible danger overhead. They also extend down towards the beak, to discern potential food sources. When inspecting an object, chickens move their heads around, so the object is viewed by several specialized areas of the retina at different angles and distances. The overall effect this may give is a clarity at least as good as our eyesight, although quite different.
Are Chickens Near- or Far-Sighted?
These color-sensitive areas act together with focusing each eye to the targets of interest. The chicken eyeball can both thicken its lens and bulge its cornea. This results in very fast change of focus.
Some people believe that the right eye is near-sighted and the left is far-sighted. This appears to be a misinterpretation of an image in a study where a hen focused on a nearby object approaching the right side of her head.
The truth is more amazing than this! Indeed, chickens can focus each eye independently, so that one can monitor the distance while the other searches the ground. Both eyes have this ability. This is really useful for foraging while maintaining a look out—vital for protection against aerial predators. Moreover, within each eye, a lower field of vision attunes to nearby objects, while the upper visual field focuses further away. The images from each eye are processed separately, unlike our stereoscopic vision. Nevertheless, chickens can coordinate both eyes when aiming a peck, only closing their eyes as they reach their target.
Chickens socialize up close and personal, as they identify and show preferences for companions at distances less than 8 in. (20 cm).
How Wide Can Chickens See?
Eyes placed on each side of the head allow chickens a wide range of vision of more than 300° with around 26° overlap in front of the head. Coupled with their vigilance and quick movements, they avoid having predators creep up behind them. The binocular overlap in front helps them to move forward and fine tune beak movements.
Why Do Chickens Bob Their Heads?
Unlike humans, they can hardly move their eyeballs to keep an image still for the 20 ms necessary to achieve a sharp image on the retina. So, instead they move their neck precisely to keep the head stationary. As they walk, they keep their head in the same place for as long as possible before moving it quickly forward, resulting in a characteristic bobbing movement. Also, if you hold a hen and move her body small distances, you will see how she compensates by keeping her head stock-still.
Rapid Observation
Chickens have lightning reflexes allowing them to catch flies and avoid capture. Their rapid detection of small movements aids this skill, meaning that they can see flicker in artificial lighting that we cannot. Humans can detect up to 50–60 Hz flicker, while most chickens see up to around 95 Hz in most conditions (some birds may see faster flicker at some wavelengths). So, it appears that fluorescent light flicker (cycling at 120 Hz in the US and 100 Hz in Europe) does not cause them any issues. Pupils react four times more quickly to light changes but do not adjust as far as humans’. Like focus, pupils can be controlled independently.
Other Aids to Vision
These amazing eyes are protected by a transparent third eyelid—the nictitating membrane—which lubricates and cleans the eye regularly and covers it when protection is needed without obscuring light.
The following slideshow depicts a colorful rooster closing his nictitating membrane over his eyes as his crow peaks. You can see the pale skin partly obscures his eye.
Outside of the eye, chickens can sense some frequencies of light in the pineal gland of the brain directly through bone and tissues. This sense regulates daily rhythms and breeding patterns.
Awareness of how differently chickens see the world is useful for ensuring that our management systems provide a pleasant experience for our birds.
Sources
- Mench, J.A., Behaviour of Domesticated Birds: Chickens, Turkeys and Ducks. In Jensen, P. (ed) 2017. The Ethology of Domestic Animals: An Introductory Text. CABI.
- Nicol, C.J., 2015. The Behavioural Biology of Chickens. CABI.
- Perry, G.C. 2004. Welfare of the Laying Hen (27). CABI.
- Feature image by Mabel Amber from Pixabay.
- Learn more about chicken behavior on the free MOOC by the University of Edinburgh: Chicken Behaviour and Welfare.
Originally published in the October/November 2020 issue of Backyard Poultry and regularly vetted for accuracy.
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