obtained by means o f birdlime; and this is evidently the way in which these birds are captured in the
neighbourhood o f Chuquisaca.
That the Humming-Bird is not altogether denied the power o f song, we learn from the notices respecting
its vocalization by various authors; but as this is a point upon which I cannot speak from personal
observation, I shall take the liberty o f quoting from those who have written on the subject. To begin
with the remarks o f my friend Mr. W. C. L. Martin:—
“ It '"is not to the most beautiful birds that the voice o f melody is given. The Mocking-Bird, the
Nightingale, and the Thrush are but plainly attired; and it would appear that if Nature be lavish in one
respect, she is parsimonious in another. On the Humming-Birds she has bestowed the gift o f beauty: she
has created them winged gems—she has chased their plumage with burnished metals or overspread it
with laminae o f topaz and emerald—she has strained, so to speak, at every variety o f effect—she has revelled
in an infinitude o f modifications, whether we look at the hue or the development o f the feathering. We
can scarcely, then, expect that, to such an external perfection, the gift o f song will be also added; and,
indeed, when we reflect upon the structure o f the tongue, o f the os hyoides which supports its base, and
o f the mechanism by which it is rendered capable o f protrusion, remembering that the os hyoides is
connected with the larynx, we cannot in reason suppose that these birds can be eminent as songsters. Nevertheless
it would appear that some species at least utter, while perched, a sort o f querulous warble.
“ The ordinary cry o f the Humming-Birds is sharp and shrill, generally uttered on the wing, and
frequently reiterated by the males during their combats with each other. It is principally, says Lesson, in
passing from one place to another, that their cry, which he likens to the syllables tere-tere, articulated with
more or less force, is excited. Most frequently, he says, they are completely dumb; and he adds that he
.has passed whole hours in observing them in the forests o f Brazil without having heard the slightest sound
proceed from their throats.”
Mr. Gosse, in his ‘ Birds o f Jamaica,’ speaking o f a species which he calls the Vervain Humming-Bird
(the Mellisuga minima of this work), says, “ The present is the only Humming-Bird that I am acquainted
with that has a real song. Soon after sunrise, in the spring months, it is fond o f sitting on the topmost
branch o f a mango or orange-tree, where it warbles in a very weak, but very sweet tone, a continuous melody
for ten minutes at a time; it has little variety. The others only utter a pertinacious chirping.”
It will be expected that some remarks should now be made with regard to the luminous character o f
certain parts o f the plumage o f these charming birds—a point which has engaged the attention o f many
naturalists and physiologists, but o f which I believe no very satisfactory solution has yet been attained.
“ A few days since,” says Mr. Martin, “■ we were examining a Humming-Bird, the gorget o f which was
an intense emerald-green ; but on changing the light (that is, altering its angle o f incidence), the emerald
was changed into velvet-black. Audebert considered this changeableness to be due to the organization of
the feathers, and to the manner in which the luminous rays are reflected on falling upon them: and o f
this, we think, there can be little doubt; for each feather, when minutely inspected, exhibits myriads of
little facets so disposed as to present so many angles to the incidence o f light, which will be diversely
reflected according to the position o f the feather, and in some positions not reflected in any sensible degree,
and thus emerald may become a velvet-black.
“ Lesson supposes that the brilliant hues of the plumage of the Humming-Birds are derived from some
elements contained in the blood, and elaborated by the circulation—a theory we do not quite understand,
inasmuch as colour is the result of the reflection of some rays and the absorption of others, caused by the
arrangement o f the molecules o f any given body. He adds, however, that the texture of the plumes plays
the principal part, in consequence o f the manner in which the rays of light traverse them, or are reflected
by the innumerable facets which a prodigious quantity of barbules or fibres present. All the scaly feathers,
he observes, which simulate velvet, the emerald, or the ruby, and which we see on the head and throat of
the Epimachi (as the Grand Promerops of New Guinea), the Paradise-Birds, and the Humming-Birds,
resemble each other in the uniformity of their formation ; all are composed of cylindrical barbules, bordered
with other analogous regular barbules, which, in their turn, support other small ones; and all of them are
hollowed in the centre with a deep furrow, so that when the light, as Audebert first remarked, glides in
a vertical direction over the scaly feathers, the result is that all the luminous rays are absorbed in traversing
them, and the perception o f black is produced. But it is no longer the same when the light is reflected
from these feathers, each of which performs the office of a reflector; then it is that the aspect of the
emerald, the ruby, &c. varying with the utmost diversity under the incidences o f the rays which strike them,
is given out by the molecular arrangement of the barbules. It is thus that the gorget of many species takes
all the hues of green, and then the brightest and most uniformly golden tints, down to intense velvet-black,
or, on the contrary, that o f ruby, which darts forth pencils o f light, or passes from reddish orange to a
crimsoned red-black.
“ It is thus, we think, that the everchanging hues of the gorgets of the Humming-Birds from black to
emerald, ruby, crimson, or flame-colour are to be explained.”
In a note just received from Dr. Davy, dated Ambleside, June 10, 1861, that gentlemen says I have
examined with the microscope the feathers o f the Humming-Bird, A g la a c tis cupripennis, you entrusted to
me, which is so remarkable for its rich colours as seen in one direction, and only one. The result is merely
the following— viz., that those feathers in which this peculiarity is most strongly marked are membranous,
terminating in pointed filaments, set on obliquely, so that looking from the head each feather is only partially
seen. This result, I apprehend, will help very little to account for the peculiarity in question. Its explanation
must be sought (must it not ?) in the higher optics.”
“ As to the question you ask me about the beautiful play of colours in the Humming-Birds,” says
Dr. Stevelly, “ I have never studied the subject, and I should greatly fear to say anything about it, particularly
if what I said were to be looked on as o f any authority.
“ There are two optical principles only which I can see to be any way concerned in such an effect. One
is the cause o f the play of colours in mother-of-pearl, and which Brewster proved to arise from very fine
striated rulings, the distance between the parallel lines not being greater than from the 10,000th to the
100,000th o f an inch. Barton, of Birmingham, imitated this by ruling very fine parallel lines on steel dies,
and then impressing these on buttons, which showed very beautiful colours when exposed to strong light.
The other optical principle, which I think, however, to be the most likely to produce the effect in the case
of feathers, is the influence o f thin plates. If you know Mr. Gassiot (one of your leading Royal Institution
savants), get him to show you some of his copper-plates, on which by an electrotype process he has had
very thin films o f lead deposited; and I think you will see colours fully as beautiful, though not as varied
or as variable in different aspects as those of the Humming-Bird.