All the birds and other surface dwelling creatures of our planet developed under the balance of light wavelengths emitted continuously by our sun. As these light waves strike the earth’s atmosphere, the length of the light waves is modified. Some of the harmful rays are filtered out by the atmosphere. The greater depth or area of the atmosphere that the rays go through, the more they are changed towards the red and infrared end of the visible spectrum. This is why the setting sun is so orange in color; its light must pass through hundreds of miles of atmosphere before it reaches our eyes. The light from the sun when it is directly overhead passes through only a few miles of atmosphere, allowing the greatest amount of unmodified light to reach the surface.
When this normal balance of light in which birds evolved is altered, as by indoor artificial lighting, there are short-and long-term effects on the birds’ lives, health, and reproduction. Some few of these more noticeable effects are now known, but most are still completely unknown. It can now be physically proven, for example, that unbalanced light that strikes the human eye will result in vastly reduced muscle power and physical ability. This unbalanced light will also affect the muscle strength of birds, and this is one reason why birds indoors under artificial light tire more easily and are easier to catch than those maintained in outdoor aviaries.
There are a wide variety of artificial light bulbs and fluorescent tubes now available, and most of these produce a balance of light wavelengths that is far different from that of natural sunlight. Some give off lightwaves that are heavily into the red and infrared end of the spectrum, such as the standard incandescent light bulb, while others are overly rich in the green, blue, or yellow wavelengths. The ultraviolet ‘black light’ tubes used in discos radiate predominantly beyond the visible violet in the invisible ultraviolet range, at the opposite end of the visible spectrum from the infrared area.
The old standard incandescent light bulbs, as already mentioned, produce light that is heavily in the red and invisible infrared wavelengths. Through we cannot see infrared radiation, we can feel it as heat. An incandescent bulb radiates a lot of infrared or heat radiation. In a small, enclosed room, one light bulb will rapidly raise the temperature of the room through its large output of heat. When used in brooders and other small enclosed places, a small bulb produces enough heat to keep the temperature of a small area very warm for young gallinaceous birds, or baby psittacines that are being hand-fed. A bulb that is too large can put out so much heat that it will dehydrate, burn and kill sensitive baby birds. A small 7-watt bulb can even be used as a temporary incubator when nothing else is available. These incandescent light bulbs do not emit any light in the ultraviolet wavelengths.
The commonly used fluorescent lighting tubes are made to emit more blue or other colors of light, depending on their purpose. Unless they are specifically manufactured to do so, they emit little or no light in the red or infrared ranges of the spectrum, and little or no ultraviolet light. Those that are manufactured as ‘daylight’ fluorescent tubes have a better balance of the light colors of the spectrum. The commercial tubes that go by the brand names Vita-Lite and Kiva have a good balance of the light wavelengths that are nearest to the balance of natural sunlight, but they range from two to ten times the cost of the standard fluorescent tubes.
A report published in the November, 1971 monthly issue of the American Cage-Bird Magazine illustrates the importance of full-spectrum lighting in maintaining any birds in captivity. The Bronx Zoo had for four years maintained a group of Tufted Puffins under artificial lights. During this time, there had been no breeding attempts. However, when the Zoo installed full-spectrum lighting, the puffins produced a fertile egg for the first time in captivity.
The basis for the observed effects of various wavelengths of light on living things is not yet understood. We do know from solid research that light affects the development of the body’s hormone-producing glands. We also know that under the stimulation of light, the pineal gland controls the synthesis and release of hormones and enzymes into the bloodstream. Perhaps most important, light received through the eye will stimulate the pituitary gland. Since the pituitary gland is the master balance gland of the glandular system and of the body, light in this indirect manner will influence all of the glands in the body. Through research has not yet pinpointed many of the physical affects of this glandular light influence, there can be no doubt that these effects are profound and far-reaching.
All of the available research now indicates strongly that light is a basic, natural regulator of many body processes and physical activities in both birds and mammals. Research by William Rowan as long ago as 1925 showed that Slate-colored Juncos could be made to migrate northward rather than towards the south in the fall by varying the light-dark cycle they were exposed to before their release. Also, experience with ducks many years ago showed that hooding them to close off light to the eyes definitely prevents the stimulation of the male sex glands.
Canary breeders have known for probably hundreds of years that the gradual lengthening days of spring are a primary factor in bringing the canaries into breeding condition. It has also been proven that these red wavelengths of the spectrum are a decisive influence in bringing birds into breeding condition. As a consequence, if you have birds that are failing to come into breeding condition at the appropriate time, you might try installing a red light bulb to increase the concentration of these wavelengths to which your birds are being exposed. Do this in addition to gradually lengthening the daylight hours for the birds.
The ultraviolet wavelengths are of particular importance for the health and breeding of cage birds. These ultraviolet wavelengths of light are invisible to our eyes and are classified into two general groups, called the long wavelength ultraviolet and the short wavelength ultraviolet. The natural sunlight striking the earth is rich in long wavelength ultraviolet, which is closer to visible light. It is also called ‘near ultraviolet’, since it is the nearest to the visible light. This long wavelength ultraviolet alone will cause pigment darkening in the skin without burning. The commercial black lights give off light in the long wavelength range of ultraviolet. Ultraviolet light will not pass through glass, but will pass through most clear plastics, and it will pass through quartz glass.
The short wavelength ultraviolet, also called ‘far ultraviolet’, is farther away from visible light. It can be dangerous, and it is the form of ultraviolet that causes sunburn with overexposure. The germicidal lamps used in hospitals to kill microorganisms emit ultraviolet light in the short wavelengths.
And yet, this short wavelength ultraviolet is not all bad, for it is this area of the ultraviolet wavelengths striking the skin that allows the formation of vitamin D3. The exposed skin of the legs, feet, around the eyes, and in other areas in some birds, exudes an oily compound that researchers have given the technical name of 7-dehydrocholesterol. When the ultraviolet rays strike this substance, they produce a chemical change in this compound that transforms it into cholecalciferol, the technical name for vitamin D3. The vitamin is then resorbed into the skin over a period of time and then enters the circulatory system for use in the body’s cells to supply the bird’s vitamin D requirement. For birds maintained indoors, window glass effectively cuts out any possibility of vitamin D3 synthesis from short wavelength ultraviolet striking the skin, since ultraviolet rays will not pass through glass. VitaminD3 is the only form of vitamin D that birds can use, the only form that is metabolically active in
the avian body. This skin synthesis of vitamin D3 is very important for birds, particularly those that eat primarily plant materials, because only foods from the animal kingdom and animal products contain vitaminD3.
Recent research has shown that many ultraviolet sources are not able to cause the formation of vitamin D3 on the skin, because of the lack of intensity in the ultraviolet radiation. The presence of ultraviolet light alone is not sufficient: the intensity is also crucial. The sun’s ultraviolet radiation, of course, does have the necessary intensity for vitamin D3 synthesis. A sunlamp also emits ultraviolet radiation in the intensity required. However, most other artificial lights do not emit radiation of sufficient intensity for the formation of vitamin D3. The full spectrum lights do not have the required intensity for the formation of vitamin D3. The full spectrum lights do not have the required intensity, and even the ultraviolet fluorescent tubes, called black lights in the lighting industry, do not emit the intensity necessary for vitamin D3 synthesis. Thus,unless the birds maintained indoors have either an hour or so a day under sunlamp radiation, or a vitamin D3 supplement in their diet,
or animal products as food to provide this vitamin, they are likely to have a serious vitamin D deficiency, leading to weak bones, thin-shelled eggs, soft-shelled eggs, and other problems with calcium metabolism.
Another proven way in which ultraviolet light affects our birds is in the sex of the offspring of our breeding efforts. The long wavelength ultraviolet seems to be the primary factor in this influence. Experiments with fish, chinchillas, and other animals show that the addition of full spectrum lights in place of the standard incandescent or fluorescent bulbs resulted in an enormous increas in the production of female offspring in breeding efforts under artificial light. In transferring this information to the frequent complaints from bird breeders that their Society Finches and Gouldian Finches are producing a vast majority of males in indoor breeding, it was only reasonable to assume that a similar lack of ultraviolet light was the cause of this common avicultural problem also.
In my own breeding, I was getting from 75% to 90% males while breeding these finches under artificial lights indoors. After reading about the effects of ultraviolet light in increasing the production of female offspring in animal experiments, I installed one four foot black light tube in my birdroom, placed so that it would shine directly into all of the cages.
This one simple change was sufficient to restore a normal 50/50 sex ratio to the offspring of all of the species in my birdroom, beginning with the next clutches laid under the new lighting system. Even the overabundant production of males in the Society Finches and Cutthroat Finches changed with the next nests of eggs laid so that the breeding birds produced an equal amount of males and females among their offspring.
Though an excess of males when breeding the canaries, budgerigars, and cockatiels may be highly desirable, since males are always in greater demand as pets and singers, a large excess of males can be a minor disaster in breeding such birds as doves and finches, which are usually maintained in pairs. Should your own birds be producing a large excess of unwanted males, you need to review your lighting conditions carefully. And keep in mind that any glass between the birds and the natural light will filter out all of the ultraviolet wavelengths. The natural light in open outdoor aviaries will provide the necessary ultraviolet wavelengths which have been proven to be so important in determining the sex ratio of the offspring. A simple four-foot fluorescent black light tube in your indoor birdroom will accomplish the same result.
Since this initial experimentation with a black light in balancing the sex ration of the offspring was so successful, it was the deciding factor in the decision to produce this Fact Sheet on the subject of lighting. Many copies of earlier editions of this Fact Sheet have gone out to aviculturists, and the feedback received has indicated that this is a solid and safe way of balancing the lighting in an indoor birdroom, which will invariably result in the production of a more balanced sex ratio in the offspring of any avian species.
For a thorough coverage of the subject of light in relation to living things, I would recommend that you read the detailed works of John N. Ott. He became interested in the effects of light through his work as a time-lapse photographer, and the information he gathered in this profession resulted in the publication of several books on this important subject matter. One that should be on your ‘must read as soon as possible’ list is his book, Health and Light.
Though chicken breeders and egg farm managers have known for many years that days lengthened with artificial lighting will cause the hens to lay more eggs, the importance of lighting has not been stressed sufficiently to bird breeders in particular and the avicultural community in general. The lighting you supply your birds will affect their disposition, their health, and their breeding. Your indoor lighting conditions may well spell the difference between success and failure in the maintenance and breeding of cage birds.