Parrots and blue light

[Pajarita]

I don't think their color sensors (single cones) actually change (that would take evolution or a defective gene so it would not happen to a number of them in a short period of time), I would think it might be more a matter of their changing the composition of the carotenoids of their oil droplets - I have no idea if this is the case but it sounds more plausible, no?

[Wolf]

No , I don't think so. I think that they just become desensitized to it. But then I could be wrong.

[Pajarita]

No, I don't think so, Wolf... because colors are perceived by specialized cones reacting to different colors (lengthwaves) so I don't see desensitization as been the process that made them blind to a particular color.

This is my line of reasoning: birds have more red/green cones than blue and that could be an issue but the cone itself is not the one that 'assigns' the color to what the bird sees, it's the brain that does it and it does it based on comparison of different cones reactions. Plus, avian cones have oil droplets that act as color filters and which color it filters depends on the particular needs of the species (they have yellow, orange, red, green and clear) so birds that hunt fish and need to see through the water clearly have yellow droplets while owls, which hunt at night, have clear droplets. So, personally, I think that their blindness to blue must be a temporary after effect caused either by a drastic change in the droplet OR by the brain 'forgetting' the blue signal but I lean more on the oil droplet explanation because they are the ones that enhance color discrimination. Mind you, I have no scientific basis for this, it's just a hunch.

In any case, I don't think that desensitization would be the right word for either because, as far as I know, there are two types of desensitization, the psychological one (aka 'exposure therapy'), which involves exposing the individual to what makes him afraid slowly and gradually until he/she is no longer afraid of it, or the physical one which involves body reactions like allergies and is, pretty much, the same as the psychological therapy: exposing the individual to small and increasing amounts of the allergen until the body gets used to it (it's one of the principles of homeopathy).

[Harpmaker]

I would think that a temporary change would be from producing a different balance of chemicals without changing the actual sensors. But while I know too much about light, I know WAY too little about parrots, so that is just a guess.