LUMINOUS BIRDS AND OTHER ANIMALS.
In floating over the great coral reef of the Florida peninsula one
day, the boat startled a number of large cranes which were standing
upon a small key; and, as they laboriously flew away, my companion, a
sportsman of experience, related to me the following incident: “Some
years ago,” he said, “I was much more confined than I am at present,
and rarely had an opportunity of enjoying hunting during the daytime;
so I began a series of moonlight excursions about the reef, generally
securing a green turtle, if nothing else, and occasionally a large bird.
“One evening I visited one of the large keys; and before I was ready
to return the moon had gone down, leaving me in the dark. It was a
perfectly calm night, not a ripple appearing upon the water, so that
every sound was heard with striking distinctness; and the break of
the sea upon the outer reef came to me in a sullen roar, occasionally
varied by the crash of some huge fish as it left the water. I was
making my way to my boat, when suddenly I perceived on the sands
several dim lights. Thinking it the reflection of the stars upon the
water, perhaps, I pushed on; and when I was almost upon them, there
came a flapping of wings, while above I saw indistinctly the forms of
several large cranes, that made their escape before I thought of
shooting. The light disappeared with them; and my opinion is, that what
I saw was phosphorescent light upon the breast of the birds.”
[Illustration:
PLATE XXVI.
LUMINOSITY OF HERON’S BREAST.]
I have been told by several sportsmen that they have heard of such
an occurrence; and I have always been impressed with the belief that
the greasy, oily, powder-down patches might become luminous under
certain conditions, but never until the present year have been able to
find reliable personal testimony. The following statement, prepared
for me by Mr. Isaac W. Worrall of Philadelphia, shows that the
phosphorescence of birds is a fact. To obtain a full account of Mr.
Worrall’s observations, I made out a list of questions, which he has
kindly answered; and which, from the great interest connected with the
occurrence, are given in full:--
“Upon what birds did you observe the luminosity?”
“The night heron (_Nyctiardea grisea_) and blue crane (_Ardea
cærulea_).”
“What was the situation of the light or lights?”
“One on the breast, and one on each side of the hips, between the hips
and the tail.”
“Upon how many birds did you observe the light?”
“Upon four different birds, including the one I shot.”
“How far could you see the lights in the living bird?”
“I saw the light plainly at a distance of about fifty yards.”
“Did you notice the reflection of the light upon the water?”
“No.”
“Was the light brilliant enough to make a reflection?”
“Before I fired, the light appeared equivalent to two candles.”
“Where was the bird you shot when first observed?”
“Standing in about six inches of water.”
“Give a practical example of its brilliancy.”
“When I aimed, I considered it equal to the light of a hand-lamp or
lantern, and could see my gun-sight quite plainly against it.”
“Could you have read by the light as it appeared when you took the bird
from the water?”
“I have read small print with a dimmer light than that upon the bird
immediately after it was shot.”
“Do you think the bird can conceal or display its light at will?”
“I know the bird has full control of the light. I saw it open and shut
it four times when I was crawling towards it. I stopped when it put out
the light, and advanced when it was displayed again.” (The bird may
have turned.--AUTHOR.)
“What was the state of the weather when you shot the bird?”
“A clear, dark night in spring.” (Kansas.)
“Did you notice the sex of the bird?”
“No.”
“How long did the light last after you shot the bird?”
“The light faded as the bird died, disappearing at death.”
“Did you notice any odor while the light was apparent?”
“No.”
“Did the luminous matter come off upon your hands?”
“I did not touch it.”
“Was the light a steady glow?”
“It lasted about as long as I could count twenty at moderate speed.”
“What was the color of the light?”
“It reminded me of phosphorescent wood, and was whitish.”
* * * * *
When my informant first observed the light, he was a hundred and fifty
feet away, and while slowly creeping toward it saw it disappear four
times, the intervals between the disappearance and re-appearance being
long enough for him to count twenty at a moderate rate; from which
he assumed that the bird has the light more or less under control,
and governs it by raising or depressing the feathers that cover the
powder-down patches. When he fired at the bird, the light on the breast
was so intense that he distinctly saw the sight of his gun against it,
and he describes its brilliancy as comparable to that of a lantern
or hand-lamp. He did not notice a reflection upon the water, as he
was some distance away, and in a recumbent position, which rendered
it impossible. The bird fell where it was standing, in six inches of
water; and taking it by the wings, he threw it upon the shore, noticing
and watching the three phosphorescent spots, one in front, and one on
each side of the hips, between the hips and the tail. The bird died
slowly, _the light gradually dying out, and disappearing entirely
with death_; a fact which I consider to be of the greatest interest,
showing that the phosphorescence is not an accidental occurrence,
depending upon a favorable condition of the greasy powder-down patches,
or associated entirely with their decomposition, but is essentially
due to some physiological action, and dependent upon the life of the
bird; and the areas of the powder-down patches may be considered true
photogenic structures. The bird shot and examined by Mr. Worrall was
known to him as the blue crane, and I assume from his description that
it is the _Ardea cærulea_. The other birds in which the light was
observed were night herons. The light was in the so-called powder-down
patches, which form a characteristic feature of the herons, and
doubtless serve the same purpose, as a lure, in all.
In a night heron, which I recently obtained from a valley among the
foothills of the Sierra Madre range, there were three of those patches,
and any heron will show them. One is directly in front upon the breast,
while the other two are upon each side, midway between the base of the
tail and the upper portion of the thigh-bone. They are not visible
unless the feathers which cover these portions are brushed aside, when
a mass of oily small plumes are seen, of a decided yellow hue, growing
closely together, and about two inches in length. A yellow powder will
be found profusely mixed among them, and is due to their barbed tips
breaking off as fast as they develop.
In my specimen, just after death the patches were quite oily, the
substance coming off upon the hands, and smelling like ordinary bird
oil. As soon as possible I took the bird into a perfectly dark room,
to test it for phosphorescent light, but not the slightest gleam was
perceptible. Just under the patches a large accumulation of fat is
seen; and from these portions probably exudes the substance, which,
during the life of the bird, becomes luminous upon exposure to the air.
In the specimen alluded to, after it had been dead for several days,
the shafts of the feathers of the patch seemed suffused with a dark
oily substance. The feathers of the powder-down patches did not burn
more readily than feathers from other parts, and the odor was the same.
These patches are not strictly confined to cranes and herons. The
kirumbo (or _Leptosmus discolor_) of Madagascar has a highly developed
patch upon each side of the rump. These birds are related to the
rollers, and are remarkable for their games in mid-air. The bitterns
have two pairs of powder-down patches, the true herons three, and the
curious boatbills (_Cochlearius_) four pairs, which, if all luminous,
must render them the centre of attraction in the South-American swamps.
The interesting oil-bird _Podargus_ (or Guarcharo), that builds in the
island of Trinidad and on various parts of the South-American coast,
is a fruit-eating, nocturnal bird allied to the night-hawks. Curiously
enough, it has no oil-glands, but two large powder-down patches, one
on each side of the rump, composed, according to Dr. Sclater, who made
the discovery, of about forty feathers each. In Plate XXVII., an ideal
view is given of the possible appearance of the light of a large heron
(_Ardeomega goliath_) of Africa.
Whether these lights are of sufficient brightness to attract fishes is
a question; but, knowing that fishes are readily attracted by light of
fire, we may well imagine that a crane or heron, if standing in the
water in perfect stillness, with this soft light a short distance above
it, might possibly avail itself of such a lure, though such a view is
purely conjectural. Mr. Charles Harris of Pasadena, Cal., informed me
that several years ago he entered a heronry in Maine on a dark night,
and distinctly observed numbers of lights too large for insects; and,
moreover, they disappeared with the birds, so that he was impressed
that there was some association between the light and the herons.
That birds should be luminous is not, perhaps, strange. Other
vertebrates appear to possess this gift in an equally remarkable
manner. Some years ago an English gentleman, a lover of sport, was
travelling in South America; and among the tales that he heard from
the natives was one that related to a monkey with fiery eyes, as they
expressed it. It seemed that one season, when the tribe was far up the
branch of a small river, a woman wandered off into the forest at night,
and returned much alarmed, stating to the rest that an animal had
appeared to her with eyes gleaming like coals. Several of the natives
went to the spot designated, and were repaid with a glimpse of the
strange creature.
Such a tale was, of course, not received in good faith, being
considered an example of the inventive fancy of these children of the
forest; yet, curiously enough, Reninger the naturalist, who travelled
extensively in Paraguay, states that he has seen the eyes of the
monkey, _Nyctipithecus trivirgatus_, so brilliant in complete darkness
that they illuminated objects at a distance of half a foot. In several
instances I have referred to the phosphorescence of animals being used
possibly as a warning; at least, this is the explanation given the
phenomena by some observers, and one of the most interesting cases that
may possibly come under this head is the luminosity of frogs’ eggs.
This has been noticed in various parts of Europe; masses of luminous
matter being found about ponds and damp places, and termed _mucilage
atmosphérique_, as it was believed by the simple peasants to be part of
the tail of comets.
[Illustration:
PLATE XX.
LUMINOUS FISH. (_Stomias boa._)]
On one occasion several peasants were travelling from one village to
another at night, when suddenly a large meteor shot across the heavens,
seeming to fall before them. A few miles farther on, in crossing a
small swamp, they found several patches of a jelly-like matter, which
gleamed as if at a white heat, which so alarmed them, that they ran
into the next village, crying that a comet had fallen, and was burning
up the earth. So much excitement was created that some scientific men
visited the spot, finding the comet to be merely the mucus that had
surrounded the eggs of a frog, and had become luminous. If the mucus
was luminous when it surrounded the eggs, we may well imagine that
birds would be deterred from eating them; but the luminosity probably
precedes decomposition in the mass after the young have escaped.
Among the lizards, a gecko has been mentioned as a light-giver, as
if these curious creatures were not remarkable enough in themselves
without this attendant phenomenon. According to Dr. Carpenter, the
eggs of the gray lizard have been seen to emit light; and in Surinam
he states that a frog or toad is luminous, especially in the interior
of its mouth. Thus we see that this strange light is found in some
form from the lowest to the highest animals,--one of the commonest of
phenomena, yet presenting a problem defying solution.