Question

The birds move their neck very often because
(a)Their ears are covered with feathers
(b)They can fly
(c)The birds' eyes are fixed
(d)The bird have small eyes

Answer 1

For parrots and pigeons, having eyes on the sides of their heads is a huge advantage. As they have only a small blind spot behind their eyes and a wider field of vision that help these birds see where they are going, while also keeping an eye out for predators that might be trying to sneak upon them.

Complete answer:
I should say at first that not all birds have their eyes on the sides of their heads. There are many birds especially like birds of prey and owls have eyes that are proportionally much larger than that of similar-size mammals. Most birds cannot move their eyes, as with larger eyes there is little or no room for the required musculature. Birds like pigeons and parrots have their eyes on the side, but some other birds such as owls have large eyes placed close together at the front of their heads – a bit like ours. All birds can still see straight ahead whether they have eyes at the front or on the sides of their heads, but that doesn’t mean all birds see things in the same way. The position of a bird’s eyes on its head can tell us a lot about how it sees the world, having two eyes means animals can see a three-dimensional image of what’s around them. So they can perceive the height, width, and depth of an object, as well as how far away it is. Where a bird’s eyes are on its head affects its field of vision – that’s how much it can see in front and to the side at any one time. Think about how far we can see to either side without turning our head: these are the limits of our field of vision. In their neck, birds have more vertebrae (13-25) to provide additional flexibility, which provides for their quick head movements. For example birds like owls can turn their head 270 degrees, while other birds have a wide field of vision as their eyes are located on the sides of their head. As a result of this degree of flexibility or field of vision, birds are provided with good compensation for being unable to move their eyes. With these characteristics combined with the physiology of two foveae, make the abrupt, seemingly unusual movements of birds' heads more easily understood.
So, the correct answer is, ‘The birds' eyes are fixed.’

Note: It is observed that most species of birds have 2 foveas, they are the temporal fovea, and the central fovea. The temporal fovea is like ours in the sense that it looks straight ahead and offers binocular vision (i.e. the temporal foveas of both eyes point in the same direction), but birds also have a central fovea, which points sideways and is, obviously, monocular (i.e., the central foveas of both eyes look in opposite directions).