To have some affect the full spectrum lighting needs to be within 2 feet of the birds cage. It also shouldn't cover the entire cage so they have a spot in their cage where they can get out of the light ...
As I understand it .. the important issue in full spectrum for birds is to imitate natural light at
noon .. The CRI should be around 91/92 and kelvin at around 5000 to 5500 .. anything lower isn't full spectrum and anything higher isn't beneficial as it relates to the needs of birds as it is no longer imitating natural light at noon ...
I'll just pass on a few points from my vet and the Atlantic Vet Hospital/Exotics Division about full spectrum ..
- If the manufacturer claims full spectrum and doesn't identify the CRI and kelvin then chances are it is not truly full spcectrum at least at the levels required to be a benefit to a bird. The CRI must be at least 91 and the kelvin should be 5000 .. this imitates the sun at noon .. anything less isn't helping at all. Buyer beware were his words .. and what is being sold for reptiles doesn't provide the proper UVA/UVB balance for a bird. I think he referred to the color rendering part wasn't adequate but I could be mistaken here ...
- Full spectrum lighting aids in the synthesis of Vitamin D which also helps in the proper use of calcium .. however, because this can also be dealt with in the diet our vet felt that more importantly full spectrum lighting allows the birds to see the colours as intended and helps with physical and mental health to allow for a daily cycle. In the winters it gets dark so early but with full spectrum lighting the bird continues to get the full advantage of daylight.
- What is good for one is not necessarily good for another .. Perk (our CAG) only gets full spectrum for 6 hours per day now so as not to encourage breeding behaviours. When we rescued him he was plucking under his wings .. our vet feels this is now habit related to prior sexual frustrations .. The lighting plays a part in encouraging and discouraging breeding behaviours .. Sméagol on the otherhand gets 8 hours ..
We currently have full spectrum lighting in the overhead fixture and each bird has a fixture within two feet of their individual cages. The individual lights are on different timers to ensure Perk gets 6 hours and Sméag gets 8 hours.
Although a bird can get sunstroke through a window they do not get the full affects of the UV as it is being filtered.
I just touched on the specifics as best I could remember them and only the areas that related to my birds ...
Hope this helps ...