"Lightning bugs" and other insects that carry lights are familiar in
many parts of the country, but who ever heard of birds that carry
lights? A strange story is told of the heron's powder patch which
makes a two-candle light, which discloses a new idea in bird lore. A
belated sportsman returning from a day's sport found himself late in
the evening on the edge of a flat or marsh which bordered the path. The
moon had not risen, and the darkness was so intense that he was obliged
to move slowly and carefully. As he walked along, gun on shoulder, he
thought he saw a number of lights, some moving, others stationary. As
they were in the river bed, he knew that they could not be lanterns,
and for some time he was puzzled; but, being of an inquisitive mind, he
walked down to the water to investigate.
As the stream was a slow-running, shallow one, he had no difficulty in
wading in, and soon convinced himself that the lights were not carried
by men, and were either ignes fatui or from some cause unknown. To
settle the apparent mystery he crept as close as he could, took careful
aim and fired. At the discharge the lights disappeared, but, keeping
his eye on the spot where they had been, he walked quickly to it and
found, to his amazement, a night heron, upon whose breast gleamed the
mysterious light.
"The sportsman told me of this incident," says a friend who knew him
well, "and, while I had often heard of the light on the heron's breast,
I never before could find anyone who had personally witnessed the
phenomenon, consequently I propounded numerous questions. The observer
saw the light distinctly; first at a distance of at least fifty yards,
or one hundred and fifty feet. There were three lights upon each
bird--one upon each side between the hips and tail, and one upon the
breast.
"He saw the lights of at least four individuals, and was so interested
that he observed them all carefully and, as to their intensity, stated
to me that each light was the equivalent of two candles, so that when
he aimed he could see the gun-sight against it.
"As to whether the bird had control of the light, he believed he did,
as he saw the lights open and shut several times as he crawled toward
the birds and he stopped when the light disappeared and crept on when
it came again. The light did not endure long after the bird was shot,
fading away almost immediately. In color the light was white and
reminded the sportsman of phosphorescent wood.
"Stories of luminous birds have been related by sportsmen occasionally,
but, so far as I know, exact facts and data have never before been
obtained on this most interesting and somewhat sensational subject. A
friend in Florida told we that he had distinctly seen a light moving
about in a flock of cranes at night and became satisfied that the light
was the breast of the bird. Another friend informed me that on entering
a heron rookery at night he had distinctly observed lights moving about
among the birds."
That herons have a peculiar possible light-producing apparatus is
well known. These are called powder-down patches, and can be found by
turning up the long feathers on the heron's breast, where will be found
a patch of yellow, greasy material that sometimes drops off or fills
the feathers in the form of a yellow powder. This powder is produced by
the evident decomposition of the small feathers, producing just such a
substance as one might expect would become phosphorescent, as there is
little doubt that it does.
The cranes and herons are not the only birds having these oily lamps,
if so we may term them. A Madagascar bird, called kirumbo, has a
large patch on each side of the rump. The bitterns have two pairs
of patches; the true herons three, while the curious boat-bills have
eight, which, if at times all luminous, would give the bird a most
conspicuous, not to say spectral appearance at night.
Some years ago a party of explorers entered a large cave on the island
of Trinidad that had hitherto been considered inaccessible. To their
astonishment they found it filled with birds which darted about in
the dark in such numbers that they struck the explorers and rendered
their passage not only disagreeable, but dangerous. The birds proved
to be night hawks, known as oil birds, and in great demand for the
oil they contain, and it is barely possible that these birds are also
light-givers. The powder-down patches of the oil bird are upon each
side of the rump.
As to the use of such lights to a bird there has been much conjecture;
but it is thought that it may be a lure to attract fishes. It is
well known that fishes and various marine animals are attracted
by light, and a heron standing motionless in the water, the light
from its breast, if equal to two candles, would be plainly seen for
a considerable distance by various kinds of fishes, which would
undoubtedly approach within reach of the eagle eye and sharp bill of
the heron and so fall victims to their curiosity. If this is a true
solving of the mystery it is one of the most remarkable provisions of
nature.
There is hardly a group of animals that does not include some
light-givers of great beauty; but it is not generally known that some
of the higher animals also produce light at times. Renninger, the
naturalist, whose studies and observations of Paraguay are well known,
tells a most remarkable story of his experience with the monkey known
as _Nyctipithithecus trivigatus_. He was in complete darkness when he
observed the phenomenon, which was a phosphorescent light gleaming from
the eyes of the animal; not the light which appears in the eye of the
cat, but shafts of phosphorescent light which were not only distinctly
visible, but illumined objects a distance of six inches from the
animal's eyes.
The subject is an interesting one and research among the various
phenomena disclosed by naturalists may discover many other animals
capable of strange illuminations.