Why is he so easily startled or frightened if I walk into the room with an unexpected object? Does he see colors? Have you ever wondered why your bunny can spot sideways movement from hundreds of feet away, but can’t find the treat you placed right in front of it?
The basics of rabbit vision – their evolution
The 1st thing to remember is that a rabbit’s visual system evolved under completely different evolutionary pressures than those that “designed” our eyes. We human primates, like our simian cousins, have forward-placed eyes that confer binocular vision and optimal depth perception. This is essential for an animal originally designed to leap through trees. Plus, we have excellent color vision, a trait that helped our ancestors find ripe fruit and tasty flowers in the forest canopy.
On the other hand, the rabbit’s visual system is designed – not for foraging and locomotion – but to quickly and effectively detect predators approaching from almost any direction. The eyes are set high and to the sides of the skull, allowing the rabbit to see almost 360 degrees, as well as above its head. Rabbits tend to be farsighted, which is why they can be frightened by an overhead plane even if their human companion can barely see it. (It could be a hawk! Run!)
When we are prey like rabbits, nature allows us to develop a vision adapted to our condition.
How do rabbits see?
Rabbits can see all around them at once. Most of their vision is farsighted (seeing better at long distance), except just in front of them where they are nearsighted. They also have a blind spot directly in front of the muzzle. Most of their vision is monocular (using only one eye), but rabbits have straight-up binocular vision. Rabbits’ vision isn’t as sharp as humans’, but they can see better in low light. Their vision is adapted to quickly see predators from any angle and to forage at dawn and dusk. They also see part of the color spectrum.
We will see this in detail.
Field of view
Rabbits can see pretty much everything around them – they have pretty close to 360° vision.
The price the rabbit pays for this remarkable field of vision is a small blind spot directly in front of its face; but the forward-placed nostrils and large spoon-shaped ears make up for this minor loss of predator detection space.
For an animal to have binocular vision, the field of vision of the two eyes must overlap to some degree. The central blind spot in the rabbit’s field of vision prevents a three-dimensional view of nearby objects. When your rabbit tilts his head and appears to be looking “sideways” at you, he is actually looking at you as straight as possible for him. As far as we know, the rabbit does not have the level of depth perception of a primate at such a close distance.
Binocular vision is how we humans see the world – our brain can integrate information from our 2 eyes and create a 3D image of what is in front of us. Rabbits only have a small part of their eyesight where they can – most of the time they rely on one eye. To get an idea of what the world is like for a rabbit, just close one of your eyes.
Is the quality of a rabbit’s vision the same at 360°?
If rabbits can see all around them, is their vision the same everywhere? The answer is no.
Rabbits look ahead to see patterns and recognize shapes
First, rabbits see patterns best using the forward-facing parts of the eye – an angle of about 60° in either direction. So if a rabbit wants to make sense of what it’s looking at, it’ll turn to something. The rear part of their vision is mainly there to warn of any movement – it could be a predator.
We know this from experiments by de Graauw & van Hof (1980), who wanted to know whether or not they could recognize patterns (tested by rewarding rabbits with food if they could). If the rabbits had to rely on 120° rear vision, the successes were linked to chance.
Click on the link to access the study by Graauw and Van Hof
Rabbits are both nearsighted and farsighted
Rabbits are usually farsighted. This means they can see objects more clearly if they are further away, and less clearly if they are too close. This makes sense – the rabbit’s main concern is to watch for any approaching predators.
However, when you get to the bunny, things change. As you move in front of the muzzle, the rabbit’s vision becomes myopic. Right in front of him (but beyond his blind spot) his vision is about -5 diopters.
Binocular vision in rabbits
As explained above, most of a rabbit’s field of vision comes from just one of its eyes, so its primary vision is monocular.
This led researchers to wonder if rabbits used binocular vision (where the brain integrates signals from both eyes together) or not at all?
They found that while they primarily use their monocular vision, rabbits can also use both eyes together: a close overlap right in front of them. So, if your rabbit is looking straight ahead, it’s possible that it perceives the 3D world like you and me.
The study that brought this to light was done using different color filters on each eye and requiring both eyes to work together for the patterns to be visible. Van Hof & Russell (1977)
Do rabbits have good eyesight?
Rabbits don’t have as sharp eyesight as humans. We can distinguish lines 1/60th of a degree apart (lines closer than that blur for us).
Rabbits don’t do as well – they can only distinguish lines at about 1/3-1/6 of a degree. It’s slightly worse than cats (1/12th of a degree) but better than rats (about 1 degree).
See van Hof (1967) for more information – abstract here.
What does it look like? If you are about 50cm from your screen, you can probably see lines 0.15mm apart. On the other hand, your rabbit will have trouble with lines that are 1.5 mm apart.
Rabbits therefore do not have as sharp a view as humans, but their eyesight is ideal for their needs.
Do rabbits have color vision? Can he distinguish the colors of his surroundings?
In general, vertebrates have 2 different types of photoreceptor cells in their retina: rods and cones. Cones confer high resolution, and if more than one type of cone is present, they also confer the ability to perceive different wavelengths of light as distinct colors. For example, we humans have 3 different categories of cones: their maximum sensitivities in the red, blue, and green regions of the spectrum. The different sensitivities of each type of cone allow us to perceive different (visible) wavelengths of light such as the colors of the rainbow.
Types of photoreceptors – cones and rods
The rods are sensitive to blue-green light (maximum wavelength 498 nm). These are used in low light conditions. It’s the rods in your eyes that work when your eyes try to adjust to the dark.
Cones are more sensitive and give us our color vision. There are therefore 3 varieties in humans:
- Red (or L-cones, most sensitive to red light at 564 nm);
- Green (or M-cones, most sensitive to green light at 533 nm);
- Blue (or S-cones, most sensitive to blue light at 437 nm).
(The L, M and S stand for long wave, medium wave and short wave, and refer to the wavelength of light)
The specifics of rabbit vision
Behavioral studies published in the early 1970s indicate that rabbits have a limited ability to distinguish between certain wavelengths of light, perceiving them as different colors.
Obviously, they can distinguish between the wavelengths we call “green” and “blue”. Although rabbits don’t perceive green and blue like us, they *can* tell them apart. This means they have limited color vision.
So rabbits have cone photoreceptors – but only green and blue cones (at slightly different peaks – 520nm and 425nm).
This means that, compared to most humans, they are slightly color blind (protanopic or dichromatic). Some humans (about 1% of men) also only have functional green and blue cones – this is a form of red-green color blindness.
Thus, rabbits see colors, but will have difficulty distinguishing between reds and greens, as well as blues and greens.
In the lowest part of the retina there is a blue streak – a crescent shape that has no green cones, but only blue cones (up to 11,000 per mm 2 ) .
How do cones help rabbit vision?
Having a wide horizontal band of cones allows rabbits to see all around them more clearly. Rather than having to look directly at something to see clearly (as humans do), rabbits have sharper vision all around them.
They are able to spot and identify attackers more easily than us thanks to this wide band of cones.
And the blue band? This is located at the bottom of the retina, which means that it is light from above that reaches it. The researchers suggested this gives great sensitivity for spotting attacks from predominantly blue skies.
In other words, the blue trail helps the Rabbit monitor the sky for threats, and the visual trail (primarily green cones) helps the Rabbit monitor the ground and the horizon.
You can read more about visual streak and blue streak in the study by Juliusson et al (1994)
The other type of photoreceptor, the rod cell, confers high visual sensitivity in low light situations, but relatively low resolution (ie a “grainy” image).
The rabbit retina has a much higher rod to cone ratio than the human retina. Although a rabbit can see better than a human in low-light conditions, its low-light image has much lower resolution (clarity) than the daytime images formed by your cone-rich primate retina.
“Can my rabbit see me clearly or am I just blurry?”
As you read this page, you focus on the letters with a tiny part of your retina called the fovea . It is a tiny cone-shaped depression in the retina, lined with high-resolution cone cells.
But rabbits don’t have their cones focused in the center, but in a horizontal trail across the retina ( this is called visual trail, see above ). Most are green cones (up to 13,000 per mm 2 ) with a few blue cones (up to 2,500 per mm 2 ). They therefore also have small retinal areas with more cones than rods. However, this “ centralis” zone is not indented and its density of cones is much lower than that of our fovea. The image formed by the central area is relatively “grainy” compared to that formed by our fovea, but it serves the rabbit well.
Using this image, your voice, your body movements and your smell as cues, your bunny can recognize you (his favorite human) – as long as you’re not carrying a scary thing that completely changes your familiar form!
How good is the rabbit’s night vision?
Rabbits see better in the dark than humans, but not in absolute darkness! They can see about twice as well as humans in low light conditions.
Rabbits have eyes adapted to function at dusk and dawn, but rabbits are not nocturnal animals. Some nocturnal animals (including cats) have a mirror-like scaffolding on the retina that helps the eye detect/optimize every ray of light (this is called the tapetum lucidum ) . Rabbits don’t and neither do humans.
Rabbits have both rod and cone photoreceptors. Rod photoreceptors help them see in low light conditions. A rod photoreceptor can detect a single photon of light. Rabbits have many more rods than cones (up to 300,000 per mm 2 – see Famiglietti & Sharpe (1995)) .
The peak concentration of rods is about twice that of humans – so rabbits can see better in the dark than humans. They have adapted to see better at dawn and dusk (they are crepuscular animals).
Under these conditions, their combination of many rods and blue and green cones allows them to spot possible threats, whether on the ground or in the air.
The rods ensure their sensitivity in low light conditions. The blue and green cones guarantee an ideal color contrast for dawn and dusk:
When the sun is low in the sky, direct light is particularly yellow, while reflected light is particularly blue. The Rabbit’s green and blue cones are ideally placed to detect any object illuminated by these contrasting colors. See Nuboer and Moed (1983)
Thus, rabbits cannot see in total darkness and are not nocturnal animals. But their eyesight is ideal for an animal that comes out at dawn and dusk in low light, wary of predators looking to surprise them.
Can rabbits see infrared?
No. _ They have weaker red light vision than us humans because they don’t have red cones in their eyes. Infrared light is beyond what is visible to them.
Do rabbits blink?
Yes , but much less often than humans. They flash approximately once every 5 minutes.
They need to blink much less because they have an extra (transparent) eyelid – called the nictitating membrane. This helps keep their eyes moist while allowing them to continue to watch for predators.
In summary :