In the ultraviolet spectrum the shortest wavelengths that the sun produces are classified as UVC which are 100% filtered out by the Earth’s atmosphere. Ultraviolet waves between 280 and 400 nanometers are further broken down into categories UVA and UVB because the effects they have on living organisms are very different.

UVA

Birds can see UVA

Birds have tetrachromatic vision, which means they can see the visible light spectrum plus the UVA spectrum. Bird experts believe this helps them with identifying food, species recognition, and mate selection.

How this actually affects caged birds is hotly disputed and highly understudied. Most of the online claims that come from lighting manufacturers and resellers are highly suspect, but there are enough independent studies that show a relationship to warrant further studies of UVA’s effects on bird behavior. One example is this 2013 study done for zoos that found a possible link between aviary housed bird behavior and UVA however the behavior observed was not significant to wellbeing.

Will UVA benefit my birds?

The short answer is that while much more research still needs to be done, there is no significant evidence that caged birds benefit from UVA.

Will UVA improve my bird’s health?

There is no scientific evidence that there is a physical health benefit to caged birds by adding UVA light.

Should I add UVA to my bird’s cage?

If you have the means (boat loads of extra cash) to add UVA then absolutely do it because it is completely safe. But here is the caveat, you should not think of UVA as a “silver bullet” to make you birds healthier, happier, and more productive because it isn’t. Many years ago, I built UVA lights and conducted an experiment. I set up eight identical cages, four with UVA and four without. Over four years (eight breeding sessions of six months each), I bred Gouldian Finches, Strawberry Finches and Canaries. If there were any benefits of the UVA, they were so slight that they were unnoticeable. This experiment is what led me to not add UVA to my lights, as the benefits would not justify the extra cost.

UVB

The current trend is for internet experts and quite a large percentage of avian vets to tell bird owners that their bird needs UVB so that it can synthesize vitamin D3. To date there has only been one published study where the relationship between UVB and vitamin D3 was tested. It can be seen here The subject birds were all African Grays, and the birds did indeed synthesize as much vitamin D3 as the birds who received it in their diet. Unfortunately, the author gave no details on how or how much UVB the birds were exposed to. What should also be noted is that the authors were not able to repeat the results on Amazon parrots.

Should I add UVB to my bird’s cage?

I recommend that no bird should be given artificial UVB. That includes any bulb that is recommended for birds and says that it has UVB, any reptile lights and any suntanning bed bulbs. UVB significantly affects birds’ eyes and many parrot owners have inadvertently caused their pet to have cataracts or blindness by misusing lights with UVB. In a study published by the Royal Society of Biological Sciences, a team of scientists studied a number of species of parrots that are commonly kept as pets and found that they possess UV-sensitive visual pigments (UVS). Consequently, their eyes are highly sensitive to UVB and overexposure can cause cataracts, macular degeneration, and blindness.

FACTS ABOUT UV WAVELENGTHS AND CAGED BIRDS:

• 90–95% of UV radiation that reaches the Earth is UVA. It’s important to note that UVA is present equally throughout the daylight hours and seasons. It can also penetrate clouds and glass.
• UVB makes up only 5–10% of solar radiation. It’s strongest between 10 a.m. and 4 p.m. and doesn’t significantly penetrate glass. Additionally, its intensity differs depending on how close to the equator you are.
• Birds can see UVA waves as well as the visible spectrum.
• UVA and UVB do not penetrate feathers.
• UVA has no known physical benefit to birds.
• UVB synthesizers, when absorbed by the skin, produce vitamin D3.
• Bird’s eyes are sensitive to UVB and overexposure can damage them.