Ultraviolet (UV) rays are a part of the sun’s light that is invisible to the human eye. UVA are the longest of the UV rays and make up more than 95 percent of the radiation that reaches the Earth.
UVA rays penetrate the skin deeply and are responsible for tanning! These rays can even penetrate clouds and glass. Tanning beds sometimes use UVA rays that are up to 12 times stronger than the sun! UVA rays can cause cancer in people, and can also accelerate the aging process and cause wrinkles. This is why sunscreen is very important: to protect the skin from these harmful rays.
While people can’t see UVA rays, birds can. UVA lighting helps birds identify ripe foods and even their own mates and other familiar birds. Because UVA rays aren’t blocked by glass, natural light through a window is a good way to provide the necessary UVA rays; however, UVB rays (see below) are blocked, so this is not a way for birds to get beneficial UVB rays. If natural light is unavailable, another choice is full-spectrum lighting, which mimics the sun’s rays, providing both UVA and UVB rays. The right type of full-spectrum light can make it almost like your pet bird has its own little sun right in your house.
UVB rays are considered the more “dangerous” of the sun’s rays. Glass blocks the majority of these rays, but surfaces like water or ice can actually reflect UVB rays back so you get hit with them twice, which is why it’s easier to get sunburned when you’re swimming or on a boat. UVB rays are commonly linked to skin cancer, so it’s especially important to protect yourself from these rays by wearing sunscreen protection.
Despite the negative aspects, there are also some major health benefits to UVB rays. Namely, UVB rays are responsible for making the precursors that help the body synthesize Vitamin D3. Without exposure to direct sunlight (not sunlight from behind a window), people and animals are at risk for Vitamin-D deficiency. This is especially true for pet birds with a poor diet and stressed, sick, or breeding birds.
Birds should have at least 20 to 30 minutes a day of unfiltered sunlight to get the UVB rays they need. Another option is full-spectrum lighting, which is designed to mimic natural sunlight. Different light bulbs have different levels of UVB rays, so ask your avian veterinarian to help determine the best light bulb for your bird.
Fun Fact: Research on Eclectus parrots has shown that both males and females have even more beautifully-colored feathers when viewed under ultraviolet light. This helps them to find each other in the wild, but it doesn’t attract predators like hawks and other raptors because they can’t see the ultraviolet rays.