Winter as we know it in most of North America is a fairly unnatural season for the tropical birds that share our homes. Psittacines and passerines native to tropical climates would never be exposed to the lower levels of humidity, cold temperatures, winter winds, snow or variations in sunlight/darkness that occur in the more temperate climes. This presents a unique set of challenges when it comes to caring for our feathered companions.
Birds originating from areas near the Equator usually experience little change in the amount of daylight that they are exposed to on a daily basis. For many species, subtle changes in the amount of daylight to darkness begins the cascade of events that initiates the breeding cycle.
As you travel north from the Equator, the amount of daylight diminishes earlier during the winter days. Many species of parrots begin to breed with increasing daylight hours. This occurs after the Winter Solstice and peaks at the Summer Solstice. The opposite occurs with the group of African parrots which breed with decreasing daylight hours. Most African bird breeders consider Labor Day as the unofficial start of breeding season, and the end of the season is Memorial Day.
Whether birds breed with increasing or decreasing daylight hours, the changes do precipitate the breeding cycle. This might be exaggerated in birds living in the more northern areas of the country.
Another consideration regarding lighting involves full-spectrum lighting. Many birds living up north still get to spend some time outdoors in the summertime and are able to enjoy the warm, sunny weather. Of course, keeping birds out of direct sunlight, away from predators and in an escape-proof cage (with properly trimmed wing feathers, of course) is vital to their safety, but there are health benefits from a bird being exposed to natural, unfiltered sunlight and that does not mean through window glass.
The best benefit is from a bird? exposure to the ultraviolet portion of sunlight (especially UVB light). For birds with an uropygial (preen) gland, the gland secretion contains vitamin-D precursors that are spread over the feathers. When this precursor is exposed to UVB light, it is converted to active vitamin D3, which is then ingested when the bird preens again. Vitamin D3 is necessary for a bird to properly absorb and utilize calcium. This seems to be especially important for the African birds, especially the African grey parrot.
I recommend that all birds be provided with full-spectrum artificial lighting in the winter-time, ensuring that the bulb produces the UVB portion of the spectrum. The light should be placed in such a manner that it will provide the UVB light to the birds, and should be changed as frequently as recommended by the bulb manufacturer. Purchase a high-quality bulb; a generic bulb, might not predictably produce strong enough UVB to be beneficial. Of course, keep inquisitive birds away from cords and the fixtures. Keep the light on a timer to control the light/dark cycle. Unless you plan to bring a bird into breeding mode, keep the cycle the same each day.
Without natural sunlight or the ultraviolet portion of a full-spectrum light bulb, some African greys or Poicephalus parrots develop a dangerous condition known as hypocalcemia. A bird suffering from hypocalcemia can appear unsteady on its feet, it might become clumsier, and this condition might even progress to seizures. Left untreated, this can become life-threatening. Blood tests can confirm low blood calcium; however, the calcium level in the blood may dip and rise.
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