I read in an article that birds bob their heads while walking because they eyes do not have an overlapping FOV.
I have no idea what that means.
In: Biology
Each eye as a field of vision (FOV). Where they overlap, you can have depth perception or a form of 3D vision.
Prey species tend to have eyes to the side, to maximize the total area of the combined fields of view, for maximum awareness of their surroundings.
Predator species often have front facing eyes with overlapping fields of vision, giving them better depth perception and tracking on what’s in front of them.
Humans can perceive depth because both eyes are close enough together on the human face to overlap with each other in terms of what image is cast on the photoreceptors in each retina. The brain is able to process this information and perceive space in three dimensions, to allow you to do things like predict the trajectory of a ball as it flies through the air toward you. The overlapping field of view is what enables the brain to triangulate the positions of the same thing in the field of view and interpret depth from the angles made by visible things in each image. For any living beings that have eyes on either sides of their faces, their brains need to tell their faces to turn to put that spatial information about their surroundings together. They cannot perceive depth in the spaces around them.
Field of view is what your eyes can see without turning your head.
Human eyes are on the front of the head. You can close either eye and still see an object in front of you well: your eyes’ fields of view overlap. With both eyes open you get more clarity and depth perception. However you don’t see objects to your side all that well, and can’t see behind you.
Many herbivorous and smaller omnivorous animals have eyes on the sides of their head. This gives their eyes more coverage to the sides and back – a huge field of view, but they barely see what’s in front. It’s just at the edge of either eye, or they have to turn their head to look forward with just one eye – you can often see birds like chickens or pigeons turn their head to study something.
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