by Michael » Mon Oct 24, 2011 1:05 pm
Birds have exquisite color vision that extends into the ultra violet spectrum. So with normal indoor lightbulbs, they lose some of the colors they'd be capable of seeing. I don't think it necessarily matters that much because they just get used to seeing objects in our home under those lights and wouldn't know what they are missing since they hadn't previously seen them in other light.
As for diet, I'm not sure that is true. They can get most of what they need from diet, but then they need natural sunlight to absorb some of the nutrition and calcify it. I'm not sure that food supplements can replace sunlight. This is why I don't fiddle around with light bulbs, I just take my parrots outside regularly whenever possible. In the winter it's much more difficult. However, I'll find the occasional above freezing day in winter and bring them out hiding under my jacket with their heads sticking out to absorb the bright sun. 10-30 minutes of sun a week is probably all they require.