by ROBERT G. BLACK, PO Box 653, Belmont, CA 94002
This article appeared in the January issue of American Cage-Bird Magazine.


All of the finches and other surface dwelling creatures of our planet developed under the balance of light wavelengths emitted continuously by our sun. As they strike the earth's atmosphere, the length of the light waves is modified and some of the harmful rays are filtered out by the atmosphere. The greater depth or space on 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.

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. For example, it can be physically proven that unbalanced light that strikes the human eye will result in an immediate reduction in muscle power and physical ability. This will also affect the muscle strength and endurance of finches and other birds, and this is one reason why birds living indoors under artificial lights tire more easily and are easier to catch than those maintained in outdoor aviaries. "There are a wide variety of artificial light bulbs and tubes now available, and most of these produce a balance of light wavelengths that is far different from that of natural sunlight. "

There are a wide variety of artificial light bulbs and tubes now available, and most of these produce a balance of light wavelengths that is far different from that of natural sunlight. The standard incandescent light bulb, for example, produces light heavily in the red and invisible infrared wavelengths. Though we cannot see infrared radiation, we can feel it as heat. An incandescent bulb produces a lot of infrared or heat radiation. In a small, enclosed room, one light bulb will rapidly raise the temperature of the room through this large output of heat. When used in brooders and other enclosed places, a small bulb puts out enough heat to keep the temperature of a small area quite 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, or kill sensitive baby birds. The incandescent bulbs do not emit any light in the ultraviolet wavelengths.

The commonly used fluorescent lighting tubes emit little or no light in red or infrared ranges of the spectrum, and little or no ultraviolet. Those that are manufactured as daylight fluorescent tubes have a better balance of the light colors of the spectrum. The commercial tubes such as "Vita-Lite" has 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 fluorescents. A report published in the November, 1971, issue of ACBM illustrates the importance of full spectrum lighting in maintaining birds in captivity. The Bronx Zoo had for four years maintained a group of Tufted Puffins under artificial lights. During this time, there has 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 glandular development. We also know that under light stimulation, the pineal gland controls the synthesis and release of hormones and enzymes into the bloodstream. Perhaps most important, light received through the eye stimulates the pituitary gland. Since the pituitary gland is the master balance gland of the endocrine system and of the body, light in this indirect manner will influence all of the glands of the body. Though research has not yet pinpointed many of the physical effects of this glandular light influence, there can be no doubt that these effects are profound and far-reaching. 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 hundreds of years that the gradually lengthening days of spring are a primary factor in bringing the canaries into breeding condition. It has also been proven that the red wavelengths of the spectrum are a decisive influence in bringing birds into breeding condition. As a consequence, if you have finches that are failing to come into breeding condition at the appropriate time, you might try installing a red light to increase the concentration of these wavelengths to which your finches 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 finches and other cage birds. These invisible ultraviolet wavelengths are classified into two general groups, called the long wavelength ultraviolet and the short wavelength ultraviolet. Natural sunlight hitting 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. The long wavelength ultraviolet alone will cause pigment darkening in the skin (tanning) without burning. The commercial black lights give off light in the long wavelength range of ultraviolet. Ultra violet light will not pass through glass, but will pass through most clear plastics and quartz.

The short wavelength ultraviolet, also called far ultraviolet, is farther away from visible light. It can be dangerous and 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-wave ultraviolet is not all bad, for it is this area of the ultraviolet wavelengths striking the skin that allows the formation of vitamin D. Recent research has shown that many ultraviolet sources are not able to cause the formation of vitamin D on the skin, because the ultraviolet radiation is not intense enough. The presence of ultraviolet light alone is not sufficient: the intensity is also crucial. The sun's ultraviolet radiation, of course, has the necessary intensity for D synthesis. A sun lamp also emits ultraviolet radiation in the intensity required. However, other artificial lights do not emit radiation of sufficient intensity for D formation.

Another proven way in which ultraviolet light affects our finches and other birds is in the sex of the offspring of your breeding efforts. The long wavelength ultraviolet seems to be the primary factor in this influence. Experiments with fish, chinchillas, and other animals showed that the addition of full-spectrum lights in place of standard incandescent or fluorescent tubes resulted in an enormous increase in the number of female offspring produced in breeding efforts under artificial light. The frequent complaint that Society Finches and Gouldian Finches are producing a vast majority of males is undoubtedly the result of indoor breeding under artificial lights that almost totally lack light in the ultraviolet wavelengths.

In my own breeding, I was getting from 75% to 90% males while breeding these finches under artificial light indoors. After reading about the effects of ultraviolet light in increasing the production of female offspring, I installed one four-foot commercial black light tube in my bird room, placed so that it shined 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 bird room Even the over abundant 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. Though an excess of males when breeding canaries, budgerigars, and cockatiels may be highly desirable, since males are always in demand as pets and singers, a large excess of males can be a minor disaster in breeding such birds as finches and doves, which are usually maintained in pairs.

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 light through his work in time-lapse photography, and has published several books on this important subject. His book, Health and Light contains excellent coverage of this subject. 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 and the aviculture community. The lighting you supply for your birds indoors will affect their dispositions, their health, and their breeding. Your lighting conditions may well spell the difference between success and failure in the maintenance and breeding of finches and other cage birds..