What Colors do Birds See?

Interesting Facts:

1. Changing the color of ambient light can trigger early breeding, or alter fertility rates through mimicking the change of seasons.
2. Birds have photo-pigments with sensitivities at four or five peak wavelengths, making them between a tetrachromat or pentachromats
3. The fovea, where there is a  high concentration of cones, may form a lateral stripe in the eyes rather than being in a central area.
4. There is a strong correspondence between the habitat and behavior patterns of different species, and their spectral sensitivities
5. The inner segment of the cones in a bird's eyes contains a colored oil droplet beside the base of the outer segment, which filters light before it can reach the visual pigment.