Abstract
Most often light is considered to be a vehicle to make our environment visible. As an indoor parrot breeder, I final it necessary to think of light in much broader terms. The consequences of the sun's radiation is greater than that portion of the electromagnetic field produced by the sun that we can see with our eyes. In addition to the visible products of
. the sun, we also need to understand the contributions of low frequency infrared waves, high frequency ultraviolet waves, and all of the consequential effects the sun would have on our birds.
Understanding my own limitations when it came to developing a lighting program for my aviary, I began by sorting out the ways I see light and the effect I believe light has on the environment and the diurnal clock of our birds.
ULTRAVIOLET
My studies have taught me that the Ultraviolet and Infrared radiation portion of light is probably the most over looked spectrum of the sun's radiation in an indoor aviary. The three most important consequences of Ultraviolet radiation in the environment are disinfection, vitamin D synthesis and the psychological well being of the birds.
Since we do the cleaning in the aviary and a good diet has adequate vitamins, we can be less concerned with lN light for these purposes but there is conclusive evidence that the lN component of light is necessary for the overall health of animals. Standard fluorescent tubes generally emit little or no infrared light and a very small amount of ultraviolet light.
INCANDESCENT
Conversely, incandescent bulbs generate a great deal of infrared light and do not emit any light in the ultraviolet wavelengths. This infrared light produced by incandescent bulbs creates a quantity of heat that may need to be factored into your management program. Infrared can be a benefit if you raise plants in your aviary as I do.
MEASURING QUANTITIES OF LIGHT
Quantities of light can be measured with a light meter. Outside on a sunny day a light meter would register in the neighborhood of 10,000 footcandles of light. The overall quantity of light in my aviaries rarely exceeds 1500 footcandles in front of the cages and is as low as 500 footcandles in the rear of the cage. Lightmeters are similar in scope to a battery tester. Instead of touching the battery to electrodes there is a small window to allow light to enter. The light is measured by the amount of electromagnetic energy entering the window. This energy level is then displayed by a needle which rises to the appropriate calibration mark on the grid. Quantities but not the quality of light can be measured with a light meter. Our goal is not to duplicate sunlight but to replicate as best as possible the portions of the suns radiation or the consequences of exposure to sunlight, sufficient to achieve our goals of maintaining a healthy and productive flock.
REPLICATING SUNLIGHT'S IMPACT
For purposes of replicating sunlight's impact on my environment and the photoperiodism of my birds, I have taken into consideration the following:
First: I looked at the obvious.
How accurately does my lighting replicate the colors. If the colors are similar to what the sun would produce then I feel I am at least on the right track. If all of the visible wavelengths are proportionally represented in my environment, then I can more confidently assume that the consequences of lighting which I have not been able to quantify or qualify are also being duplicated as well.
Second: What is the psychological impact of light? Are the birds acting happy, breeding well, remaining healthy? Within a limited time frame (10 years) this is one of the most difficult aspects to get a handle on. I have had breeding successes and failures with healthy breeding stock both indoors and outdoors. There are a multitude of factors involved in a high density indoor breeding facility that it would take many years of not changing any of the other environmental factors to determine these parameters. In this relatively new industry there is not yet enough known about the factors that influence reproduction to accurately test this on large parrots. However there is a great deal of information known about the productivity of humans, animals and plants involving standard lighting verses full spectrum lighting. As an example, it has been shown that students consistently score higher grades when schools switched to a full spectrum lighting system.
Third: What impact does the length of daylight have on activity level and reproductive urges? Most of the parrots I raise originated from somewhere between the Tropic of Capricorn and the Tropic of Cancer. Between these two points of latitude the seasonal day length varies much less then it does in Ohio.
None the less, in captivity, we see differences in activity level and reproduction with different day lengths. My observations point to the short day length as being the most important light-induced cue regarding reproduction. I believe this to be the case since
the birds initiate their mating rituals and nest building habits as a response to the incremental increases in day length. Therefore, without a prior shorter day length you can not have a response to a greater day length.
There are habits that occur as the day cycle lengthens, but these habits of the male feeding the female, the female spending more time in the box and the subsequent egg laying appear to he a response to the behaviors started while the day length is shorter. It has been shown in other birds that after a breeding period they will become nonresponsive to photostimulation and it is necessary for the short day lengths to reactivate the photoreceptive system.