Geese can see better, further and a wider range of colors than humans can. This helps to guarantee their survival against predators and to find food. Geese, like most other types of birds, rely mainly on their eyesight for survival.
In fact, eyesight is the dominant sense that a goose possesses, far more highly developed than their sense of taste or hearing.
As a result, goose eyesight is highly evolved - far more so than even human eyesight.
All About Goose Eyesight
It might surprise you to discover that geese not only see in color, but that they can actually see a wider range of colors than even we can!
Because of the way their retina work, they see four primary colors, instead of the three that the human eye sees.
They can see red, yellow, blue plus green more vibrantly than we do. The green vision, I assume, helps them to find the most tender grasses, weeds and shoots to nibble on.
Kaleidoscope Vision?
And thanks to an extra set of cones in their eyes, geese, like chickens, ducks and other birds, can see colors near the ultraviolet spectrum that are invisible to the human eye.
This aids them in choosing mates, identifying their healthiest offspring, detecting predators and finding food.
All super important if you're a goose!
Night Vision
Geese also see pretty well in the dark, with night vision that is more than ten times greater than ours.
Of course domestic geese can't fly, but wild geese will often fly at night because it's cooler, so that night vision comes in handy.
In addition to having good night vision, they also have excellent memories, being able to identify landmarks from previous flights.
No Binoculars Though!
Another difference in goose eyesight is that they have predominantly monocular vision instead of binocular vision like humans. Since their eyes are located on the side of the head instead of the front, only one eye can look at a single object at a time.
However, this monocular vision allows each eye to be used separately. This way they greatly increase their field of vision, however their depth perception is more limited.
Humans with binocular vision have better depth perception, but our range of vision does overlap considerably because our eyes are so close together.
That said, geese do have a very narrow field of binocular vision - basically just right in front of their bills.
Panoramic Vision
Scientists have determined that geese have nerves in their eyes that are distributed in a way that enables them to see clearly over a wide range, and in fact, their vision is angled at a slight incline to the horizon.
This enables them to see both the ground and sky clearly at the same time and gives them near panoramic vision. This is very helpful when they're grazing out in an open field.
Geese can also see objects clearly up to three times further than humans can, although they have to tilt their head, for example to watch a plane or hawk flying overhead.
And they compensate for not being able to see the whole panorama ahead of them by quickly swinging their head from side to side.
This allows them to see the object in front of them with one eye from two different angles almost simultaneously.
360 Degrees
Geese, like ducks, have a 360 degree range of vision. 180 degrees on each side, both horizontally and vertically. Conversely, most humans only have a 150 degree total range.
Geese Enjoy Unihemispheric Slow-Wave Sleep
Also like ducks (as well as chickens), geese can let one hemisphere of their brain sleep and rest, while the other side stays wide awake to keep an eye out for predators. This is called Unihemispheric Slow-Wave Sleep.
Instead of closing both eyes and letting the brain lose consciousness, many aquatic and avian species including ducks and geese close one eye and let half of their brain go into a form of non-rapid eye movement deep sleep, while keeping the other eye open and the corresponding half of their brain alert.
Migrating birds and waterfowl use this technique during their migratory flights, basically the equivalent of the co-pilot flying the plane while the pilot naps! It also comes in handy to allow the birds to rest while still staying alert to possible predators.
They can also close both eyes and enjoy a "normal" sleep period giving both sides of their brain time to rest.
I guess the moral of the story is ....good luck hiding from a goose!
