Deer have unique eyes that allow them to see the world in a different way than humans do. Their vision is adapted to their lifestyle as prey animals that need to detect predators and forage efficiently. Some key facts about deer vision include:
| Wider field of view | Deer have a field of view of about 310 degrees, allowing them to see behind themselves without turning their heads. Humans have a field of view of around 180 degrees. |
| See more blue and ultraviolet light | Deer see blues and violets better than humans. They can also see some ultraviolet light, which is invisible to humans. |
| Better motion detection | A deer’s eyes are optimized to detect motion quickly. This helps them react faster to predators or prey. |
| Greater light sensitivity | Deer retinas have a high concentration of rod cells, which improves their vision in dim light. They can see well in light conditions 7 times dimmer than humans. |
In this article, we’ll explore deer vision in more detail, looking at how their eyes work, what deer can and can’t see well, and how their vision compares to human sight. Understanding deer eyesight gives insight into their behavior and needs as wildlife.
Anatomy of deer eyes
A deer’s eyes have several special anatomical adaptations that improve their vision for survival:
Placement on the head
Deer have large protruding eyes located on the sides of their head. This gives them a wide field of view with minimal blind spots. They can see almost all the way around their body without needing to move. Having eyes on the sides rather than the front also allows each eye to scan independently for predators.
Large pupil size
Deer pupils are much larger than human pupils. At around 28mm in diameter when fully dilated in darkness, they can let in a huge amount of light. This helps deer see well in dark conditions. The large pupils also aid motion detection.
High rod density
The deer retina contains a very high density of rod photoreceptor cells. Rods function better than cones in dim light. The abundance of rods allows deer to see in light conditions up to 7 times dimmer than humans can tolerate.
Tapetum lucidum
Behind the retina is a reflective layer called the tapetum lucidum. It acts like a mirror, bouncing light back through the retina for a second chance at detection. This doubles the light sensitivity of the eye, further aiding night and low light vision. The tapetum lucidum is what causes the eye-shine effect of deer eyes at night.
Large optic nerve
Deer have a very large optic nerve relative to their eye size. This carries visual information to the brain faster, speeding reaction times.
Deer field of view vs humans
One major difference between deer and human vision is the width of view. Deer have a field of view spanning approximately 310 degrees. This means they can see almost all the way behind themselves without needing to turn their head.
In contrast, humans have a field of view of around 180 degrees. Humans have forward-facing eyes, which gives good depth perception but reduces peripheral vision.
The advantage for deer is that they can continuously scan for predators sneaking up on them, even from behind. A disadvantage is that they have poorer depth perception and judge distances less accurately, especially right in front of their head.
| Species | Field of view |
|---|---|
| Deer | 310 degrees |
| Humans | 180 degrees |
Color vision
Human and deer eyes both contain cone photoreceptor cells. Cones allow color vision by detecting different wavelengths of light. However, deer have some differences in their cone cells that change how they see color.
Deer have a higher proportion of cones that detect blue and ultraviolet light wavelengths. They are less sensitive to oranges and reds. This is why hunters wear blaze orange clothing – it appears grayish to deer vision.
Deer also have an additional type of cone that can detect some ultraviolet light. This extends their color vision into the ultraviolet spectrum. Many flowers and plants reflect UV patterns that are invisible to humans but visible to deer. This may help deer spot nutritious vegetation.
Overall, deer see blues, violets and ultraviolet tones better than humans. But they see red and orange hues poorly. Their color vision is shifted towards the shorter wavelength end of the spectrum.
Motion detection
Detecting movement quickly is very important for prey animals like deer to avoid predators. Deer eyes have special adaptations that allow rapid motion perception:
Streak retina
The retina has horizontal streaks of high ganglion cell density aligned with the horizon. This area is optimized for detecting motion rather than detail.
Fast information processing
Large optic nerves transfer visual motion signals rapidly from the eye to the brain. This reduces reaction time.
Speedy saccadic eye movements
Deer can quickly scan for motion by making fast saccadic jumps of their eyes from point to point. Their eyes can change position up to 70° in just 100 milliseconds.
These adaptations give deer superior ability to detect motion compared to humans. While human vision is higher resolution overall, a deer’s vision excels at catching sudden movement to help it react faster.
Light sensitivity
Deer are highly sensitive to light, able to see well in conditions much dimmer than humans can tolerate. Several eye adaptations maximize their ability to capture light:
- Large pupil size – Dilates to around 28mm diameter in darkness.
- High rod density – Rods detect light signals better than cones.
- Tapetum lucidum – Reflective layer bounces light through retina twice.
In twilight conditions, deer can still see while humans struggle. Deer may remain active and continue foraging after dusk longer than we might expect.
Experiments have shown deer can detect objects in light intensities around 0.00006 lux. This is over 10 times dimmer than the sensitivity of human vision at around 0.0001 to 0.0003 lux.
Deer eye shine
Deer eye shine is a phenomenon where deer eyes appear to glow bright white or yellow in the darkness when light shines on them. This eerie glow is caused by the tapetum lucidum – the reflective membrane behind the retina.
When bright light enters the eye at night, it passes through the retina then hits the tapetum lucidum. This reflective surface bounces the light straight back like a mirror. The light makes a second pass through the retina, doubling the signal to the deer’s visual system.
This eye shine helps deer vision by giving light a second chance at stimulating the rods and cones. But it has a downside of making the deer eyes visible to predators. Deer may try to hide their glowing eyes from hunters and predators by avoiding bright lights.
Comparison to human vision
Deer have a number of advantages and disadvantages relative to human eyesight:
Advantages
- Wider field of view
- Better motion detection
- Enhanced light sensitivity
- See some ultraviolet wavelengths
Disadvantages
- Narrow binocular field for judging distance
- Lower acuity and detail vision
- Poorer red and orange color perception
- Vulnerable to eye shine at night
In summary, deer vision excels at detecting motion and light signals. But human vision has higher resolution with better depth perception, especially right in front of our eyes. We also have trichromatic color vision across the full visual spectrum.
Impacts on deer behavior
Understanding deer vision helps explain many aspects of their behavior in nature:
- Grazing with head up – Deer lift their head frequently while eating to scan widely for predators.
- Freezing then fleeing suddenly – Motion detection prompts fast escape from threats.
- Herd grouping – Many eyes scanning for predators is safer.
- Browsing at dawn/dusk – Low light vision allows extended feeding times.
- Hiding at night – Avoid shining lights to conceal glow of tapetum lucidum.
Knowing what deer can see, how well they see it, and the limitations of their vision helps us understand their needs as wildlife and interact with them appropriately. Their eyes are finely tuned for survival as prey.
Conclusion
Deer have remarkable vision adapted to their lifestyle. Key features such as a wide field of view, acute motion detection, light sensitivity and UV perception allow them to detect threats, find food, and navigate safely. While less detailed than human sight, deer eyes give them advantages that aid their survival. Understanding the capabilities of deer vision provides insight into their behavior patterns and needs. We can use this knowledge to manage their habitat and interact with them safely.
