BIRDS & LIGHTING - Incandescent Lights

INCANDESCENT LIGHT BULBS

There are many forms of incandescent light sources.  These may be conventional
“Mazda” type screw in bulbs, Neodymium “full spectrum” bulbs, quartz halogen systems, and “heat lamp” type systems.  All rely upon the basic design of the incandescent lamp.  In terms of output, these devices may vary widely in their spectral outputs and lumen intensities.

We shall begin with the common Mazda type and its general illumination variants.  As noted in the precursor article on incandescent lighting, most of the output of incandescent is loaded into the infrared portion of the spectrum.  The peak output is  approximately 10,000 Angstroms (1000 nanometers), and falls in a linear manner through the visible spectrum to approximately 3500 nanometers, or about the center of the Near (UVA) range.  Thus, the majority of the output of the conventional incandescent lamp is in the lower, yellow to red segment of the visible spectrum.  Figure 1 shows the relationship of conventional incandescent light with that of normal sunlight.

FIGURE 1 - INCANDESCENT LIGHT AND NATURAL SUNLIGHT

Many configurations of these lamps are available.  The clear envelope type more closely approximates the output shown in the diagram, but tends to favor the yellows and cast shadows.  To alleviate these effects, manufacturers commonly include a diffusion layer on the inside of the glass envelope.  This increases scattering of the cooler, higher spectrum colors (viz. green and blue) into the warmer reds and yellows.  It also reduces shadowing.  Some types of bulbs, such as bright white and “reader” (which have a matte finish on the outside as well) varieties, coat the inside of the envelope with a special white material which reduces the reds, and gives a general illusion of a whiter light.  The reader bulb is also generally larger to increase this effect.  Some manufacturers merely
put a bluish filter along with the whiting material, or as an exterior coating to produce and accentuate the shorter, blue end of the spectrum.

Certain elements in thin layers have the properties of filtering out sections or frequencies of the visible and ultraviolet (UV) spectrum.  It was discovered that the rare earth element Neodymium in thin layer dispersal has the abilities to filter out much of the orange to red portion of the visible spectrum.  This accentuates the outputs of the shorter wavelength blue and green components of the visible spectrum.  A typical example of the appearance of the Neodymium bulb is shown in Figure 2:

FIGURE 2 - NEODYMIUM INCANDESCENT

While these bulbs appear to lend a more natural, whiter light to illuminated areas, it needs understood that there is absolutely no differences in the relative strength of spectral output for shorter wavelength light.  In fact, the elimination of the lower red wavelength may possibly act to suppress the breeding instinct, as the perception of the bird would be one of a natural winter sunlight, one that is deficient in the lower spectrum due to decreased photoperiod and incident angle of the sun.  These devices also produce no UVB,  have the same concentrations of UVA,  and lack the vitamin synthesis necessary wavelengths of UVB.  In this respect, they are no different than the standard incandescent lamp.  They are not recommended for avian application, and should be used with extreme caution for any lighting  purpose around breeding areas.

Another incandescent design is that of the halogen lamp.  A small amount of a halogen gas is injected into the incandescent envelope.  This addition creates a much brighter light, as the filament can incandesce at a much higher temperature than is possible with conventional lamps.  The result is a brighter, whiter light.  These lamps emit larger quantities of UVA energy, and as a result often require filter glass for protection of the eyes.  They also generate large amounts of heat due to the higher temperatures.  For general lighting, these devices make a good selection (although they are notorious power consumers), but are not appropriate for avian applications.

There are various pressurized vapor systems that combine filament and plasma
technologies.  Among these are mercury vapor, sodium vapor, and halide systems.  The mercury and halide systems are prestigious producers of UVA wavelengths, but this is of no consideration for avian application.  The light generated from these systems tends to one end of the spectrum or the other, and nowhere approximates anything healthful to avian species.  Leave them for their intended purposes, the lighting of building exteriors and parking areas.

Incandescent bulbs intended for plant growth concentrate their energies in the red and blue areas of the spectrum.  This is accomplished through the use of filtering emulsions on the inside and outside of the glass envelope, and in the glass of the envelope itself.  These products are not remotely “full spectrum” in the context that flourescent grow lights are, and should not be used in any animal application.  Anecdotal information relates certain behavioral problems associated with these lamps, including feather and toe picking, and aggressive behaviors.

Heat lamps are high-wattage floodlamp systems which have a red filter medium over the face of the unit, combined with a reflector surface on the housing of the envelope.  The sole purpose of these lamps is to provide a spot heat source in larger aviary applications.  Undocumented uses of heat lamps and red spectrum frequencies include limiting picking type behaviors (Dr. Leyland Hayes, Gamebird Publications) and increasing clutch sizes of laying hens in poultry applications (USDA).

As to so called “blacklight” incandescent, I do not recommend them for any application, as they provide nothing useful for vitamin synthesis, and are potentially damaging to the human (and by extension, avian) retina’s.

A final note.  Incandescent lights provide a general lighting solution for work areas and living spaces.  They are not full spectrum, and can never be engineered to be so, irrespective of any claim to the contrary.  White light neodymium bulbs may inhibit breeding behaviors, and are not a valid substitute for a good full spectrum fluorescent array.  Use incandescent devices for human lighting, not for birds.

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Last Updated 01/30/99