Margaret A. Wissman, DVM
Posted: March 29, 2011, 12:00 a.m. PST
Who doesn't enjoy walking outside in the sunlight, feeling the warmth of the sun on our skin? You might not know that we are receiving a wonderful benefit from natural sunshine. Upon exposure to the ultraviolet portion (UVB) of sunlight, a complex set of biochemical reactions in the skin occur that result in the production of active vitamin D3, also called the “sunshine vitamin.” This vitamin is very important for the proper absorption and utilization of calcium, which has many important functions in the body.
By Gina Cioli/I-5 Studios/Courtesy Maria Brown
African parrots, including African greys, that are housed outdoors, and therefore exposed to natural unfiltered sunlight, rarely suffer from hypocalcemia (low blood calcium).
Most people spend enough time outdoors to benefit from the exposure to ultraviolet light; however, those who apply sunscreen every day to their exposed skin and the bed-ridden (or others who never spend any time outdoors) can suffer from hypovitaminosis D, or calcium-deficiency related diseases.
Now, think about our pet birds. Most pet birds spend all of their lives indoors, except for the occasional trip in a plexiglas carrier or covered travel cage to the vet or groomer. You might think that your pet bird receives adequate light exposure because it sits by a window and you often see it enjoying the warmth of the sun. However glass, plastic and even fine-mesh screening filters out most of the beneficial UVB rays of the sun.
There are two types of vitamin D: ergocalciferol, vitamin D2, which is a plant derivative, and vitamin D3, called cholecalciferol, which is produced in the bird's body. Birds can produce vitamin D3 in the skin or in sebaceous secretions when irradiated by ultraviolet light.
Reaping The Benefits Of Light
All pet birds should be allowed exposure to natural, unfiltered sunlight for about an hour or two per week, ensuring that they have access to shade and cool water and that the cage is predator- and escape-proof and with supervision.
If that is not possible, use a full-spectrum light that emits the UVB portion of the spectrum. This can be placed near the bird's cage, safely away from inquisitive beaks and feet, yet close enough to provide the benefits of the ultraviolet light. Lights that mimic natural sunlight might not always be full-spectrum, so read the product information to ensure that the bulb emits UVB light.
It pays to purchase a good-quality, name-brand light. Studies have shown that generic full-spectrum lights produce UVB light unpredictably for varying amounts of time. The light should be changed frequently, as recommended by the manufacturer. The light might appear to be functioning properly; however, the ultraviolet portion can peter out unbeknownst to you.
Ultraviolet light is necessary for birds to produce the active form of vitamin D3. Without vitamin D3, pet birds are not able to properly utilize calcium, a mineral that is vital to bone health. Calcium is also important for the proper functioning of muscles, blood coagulation, electrical conduction of nerves and for egg production.
Female pet birds, especially those that are reproductively active, also benefit from exposure to UVB lighting to optimize their calcium utilization. Breeder birds housed indoors should be offered full-spectrum lighting that provides the UVB portion of the spectrum. This, along with a calcium-rich diet, helps prevent egg-related problems.
The uropygial gland, in addition to producing antibacterial/antifungal substances for the skin, waterproofing substances for feathers and other substances that help keep feathers moist and supple, also makes vitamin-D precursors, which are spread on the feathers during preening. When exposed to UVB light, these precursors are then converted to active vitamin D3, which is ingested during subsequent preening activity. It is because of the exposure to UVB light (either from natural sunlight or when provided by a light bulb that provides the UVB portion of full-spectrum lighting) that birds possessing an uropygial gland can properly utilize calcium. (The purple macaws and Amazons do not have an uropygial gland, so it is theorized that they rely on production of vitamin D3 in the skin only.)
Birds suffering from hypovitaminosis A (vitamin-A deficiency) might not be able to produce the correct vitamin-D precursors in the uropygial gland due to a condition called squamous metaplasia. Birds suffering from hypocalcemia should also receive beta-carotene as a supplement, in addition to offering the bird dark green leafy vegetables, as well as orange, red and yellow fruits and veggies. Beta-carotene is converted into active vitamin A in the body, and the unused portion is excreted unchanged, so it is much safer than providing a vitamin-A supplement, which can be toxic if overdosed.
Some birds might pluck out the wick feathers to the uropygial gland, making it difficult or impossible for the secretions to properly release from the gland. These birds might suffer from squamous metaplasia of the uropygial gland, as well. I have seen obstructed uropygial glands in some parrots where the little channels that deliver the secretions become occluded with the dried secretions, preventing their release. Hot-packing the area over the gland and gentle massage can help to unblock the channels, allowing the secretion to flow normally again.
There really is no adequate replacement for natural sunlight, but if this is not possible, you should provide your bird with a good-quality artificial light bulb that emits the ultraviolet portion of the spectrum.
Can birds get sunburned? Yes! Over-exposure to direct sunlight (the ultraviolet portions of the spectrum: UVA and UVB) can cause sunburn on the unfeathered facial skin. Feather-plucked birds can also get sunburned skin on the areas with no feather covering, although I have not seen this occurring as frequently as sunburn of the face. The feet, covered with scales, are protected from most of the effects of sunburn. Mutations that cause a bird to be of a color palette that is not the natural “wild-type” color are more susceptible to the effects of the sun's burning rays.
Studies have shown that beta-carotene can help prevent sunburn from the inside-out, as it might reduce UV-induced redness, and it appears to be somewhat helpful in reducing the risk in sensitive humans. This mechanism might help birds, as well.
Birds can also become sunburned from a full-spectrum light. My friends, Nina and David, have a darling Cape parrot, Griffin, that loves to bask up close to his full-spectrum light. One day, half of his facial skin turned bright red. We discovered that he got a sunburn from sitting too close to his new light.
By Gina Cioli/I-5 Studios/Courtesy Omar's Exotic Birds
Macaws with exposed skin may get sunburned more easily than other parrots.
As with people, sunburn should be prevented as much as possible, as the changes to the DNA in skin cells can eventually result in skin cancer, although this is not that common in birds as it is in people.
Interestingly, young birds housed outdoors, and therefore exposed to natural sunlight, often undergo the change in the color of their irises that occurs as they age much earlier than birds kept indoors.
African Grey Health
African parrots, including African greys, that are housed outdoors, and therefore exposed to natural unfiltered sunlight, rarely suffer from hypocalcemia (low blood calcium). Seizures are one sign of hypocalcemia commonly seen in African grey parrots housed indoors that are not provided with a full-spectrum light. Hypocalcemia should not be ruled out in a seizuring African grey parrot or a member of the Poicephalus parrots group just because the blood calcium level is within the normal range during testing. Calcium levels dip and rise according to circadian rhythm. Normal calcium levels for psittacines range from 8.0-13.0 mg/dl. Running an ionized calcium level can be diagnostic; however reference ranges for the different species are not yet established or published for many species.
Learn more about lighting by checking out these articles:
UVA & UVB Lighting: What Is It?
Your Pet Bird's Daytime & Nighttime Needs
Excerpt from BIRD TALK Magazine, with permission from its publisher, I-5 Publishing LLC. To purchase digital back issues of BIRD TALK Magazine, click here.