Cones allow the brain to perceive colors. Nocturnal birds who have the extremely high concentration of rods will have very few cones - it is much more important to be able to see in low light and not very important to distinguish colors. On the other hand, birds who forage and feed in the daylight see colors very clearly from far off. It's been said that a hummingbird can spot red flowers from over a half mile away. There are also foveae , which are zones of maximum visual sharpness.
People have one fovea.
Some types of birds, such as hawks and eagles , have two, allowing them to have a type of double vision. The color of birds' eyes depend on the species. All of the same species will normally have the same color of eye. The only exception is when an albino bird occurs. This bird will not have the normal color eye of its species but have a white pink colored eye.