Birds and Nature, Vol. 10 No. 3 [October 1901]

THE BLACK-THROATED GREEN WARBLER
(Dendroica virens.)

One of the interesting nature studies is an investigation of the groups of insect-eating birds in reference to their food and the methods employed in obtaining it. Some insects are useful to man, but by far the larger number are a detriment to his interests in one way or another.

The swallows and swifts are almost constantly on the wing, dexterously catching any insects that come in their way. They are day birds and at night are replaced by the nighthawks that feed upon the night flying insects. Next are the flycatchers that dart “from ambush at passing prey, and with a suggestive click of the bill, return to their post.” The beautiful little hummingbird, ever active on the wing, quickly sees and picks from leaf or flower insects that would escape the attention of other birds. The woodpeckers and allied birds examine the tree trunks and carefully listen for the insect that may be boring through the wood within. The vireos, like the good housekeeper, examine the “nooks and corners to see that no skulker escapes.” The robin and its sister thrushes and the numerous sparrows attend to the surface of the earth, and aquatic birds extensively destroy those insects whose development takes place either in or on the water.

Not the least among the birds that assist man in his warfare upon insect pests are our beautiful and active warblers that frequent the foliage of tree and shrubs patiently gathering their insect food.

One of these is the Black-throated Green Warbler of our illustration. If we desire to examine its habits, except during the period of migration, we must visit the forests of cone bearing trees in the northern woods of the eastern United States, in the Allegheny mountains and from these points northward to Hudson Bay. It is almost useless to seek this bird in other places. Here, high up in the cedars, pines and hemlock in cozy retreats far out on the branches it builds its nest. “The foundation of the structure is of fine shreds of bark, fine dry twigs of the hemlock, bits of fine grass, weeds and dried rootlets, intermixed with moss and lined with rootlets, fine grass, some feathers and horse hair.” The nests are usually bulky and loosely constructed. These rollicksome Warblers have a peculiar song which is very characteristic and not easily forgotten. The descriptions of this song are almost as numerous as are the observers. One has given this rendering: “Hear me Saint Ther-e-sa.” Another has very aptly described it as sounding like, “Wee-wee-su-see,” the syllables “uttered slowly and well drawn out; that before the last in a lower tone than the two former, and the last syllable noticeably on the upward slide; the whole being a sort of insect tone, altogether peculiar, and by no means unpleasing.”

The song of the Black-throated Green Warbler is so unlike that of the other warblers that it becomes an important characteristic of the species. Mr. Chapman says, “There is a quality about it like the droning of bees; it seems to voice the restfulness of a midsummer day.”

Those who wish to observe this bird and cannot go to its nesting retreats, in the evergreen forests, must seek in any wooded land during its migrations to and from the tropics, where it finds an abundance of food during the rigors of our northern winters.

A LIBEL ON THE BIRDS

A few days ago I was watching the curious actions of a sparrow on the sidewalk in a rather quiet part of town. On either side of the street were lofty brick and stone buildings, with the usual multiplicity of little niches and cavities in and about the projecting cornices and ornamental architecture. These sheltered and inviting ledges had been utilized from year to year by divers smaller tribes of the feathered folk as nest-building sites, and the little bird which had attracted my attention had already laid the foundation timbers of its prospective house in a cosy niche of the cornice almost directly over my head where I was standing.

It was plainly evident that the sprightly creature was seeking sticks of proper length and strength to barricade a broad hiatus in the front part of the cavity it had chosen for its future home.

This opening was angular in form with the vertex at the bottom and its sides separating outwards towards the top, where there was a span of perhaps four or five inches.

As I stood with my elbow resting against the low paling the confiding sparrow hopped to within a yard or two of my feet in searching for tiny twigs that had fallen from the overhanging shrubbery.

It picked up a great many pieces and as quickly dropped them. Then it would stand perfectly still for a few minutes intently scanning the limited landscape as if in a brown study as to what move it should next make.

Finally it set vigorously to work picking up bits of material from an inch or two to six inches in length. Instead of flying away with a load it dropped them in a little heap nearly if not quite parallel to each other. Then poking its beak into the pile and throwing the sticks hither and thither it settled down to practical business by seizing a stick of medium length and flying away with its burden dangling in the air. Of course, I watched the little architect and saw her mount straight up to the chosen ledge and deposit the twig exactly crosswise of the gaping notch. This operation she repeated several times, always throwing the sticks about as if intent upon selecting a piece of special dimensions. No human carpenter with measuring rule in his hand could have been more expert.

In a moment the truth flashed into my mind and I realized that I was verily the human pupil of a little bird made famous by honored mention in Holy Writ.

Why, the cunning worker had foreseen to the ridicule of my own confessed stupidity that in order to effectually bar the exposed side of the chamber it must of necessity select girders of successively increasing length and size. Thus, as I fancied it reasoned, a short stick would not span the top of the dangerous gap; while, on the other hand, a long stick could not be used at the bottom because it would strike smack against the side walls before it could be placed in position low enough. So all this clearly explained why the bird should exercise such studied care in selecting the large “timbers.”

A few days afterwards I visited the scene of operations again, and by using an opera glass found that the nest was very nearly if not quite finished. The menacing gap in the ledge no longer existed; for there was a solid bulkhead in its stead composed of longitudinal sticks tied and stiffened by interwoven bits of dry grass and such shreds of various waste material as only bird intelligence knows where to find.

More interested now than ever, I took pains to climb into the attic of the three story building where from a narrow gable window I could look obliquely down into the pretty nest now neatly lined with tiny feathers and thistle down. So much, then, for the sparrows and their house building. I say sparrows now, for during my later observations I had seen both Mr. and Mrs. Sparrow diligently working together.

But to advert now to our alleged “libel” on the birds, I have only to say that it is very convenient for great men and ponderous books to tell us that the lower animals perform their actions by means of a tendency called “instinct;” and thus divest themselves of all further responsibility in the matter. Confronted by this obscure declaration we are led as pupils in natural history to ask, “What is instinct?” The following definitions of this much-abused term are, perhaps, the best to be found in the English language:

“Instinct is a propensity prior to experience and independent of instruction.” – William Paley.

“Instinct is a blind tendency to some mode of action, independent of any consideration on the part of the agent, of the end to which the action leads.” – Richard Whately.

“Instinct is an agent which performs blindly and ignorantly a work of intelligence and knowledge.” – Sir William Hamilton.

Now such names as Paley, Whately and Hamilton stand high upon the roll of honor in the sparkling literature of our language; and yet the words of these great scholars are but as sounding brass and a tinkling cymbal when they undertake to tell us what is the real import and inwardness of that occult and wonderful faculty in the mental essence of animals which scientists by force of circumstances have agreed to call “instinct.”

“Aha!” my little sparrow would say, could she speak our language, “we perform our actions neither blindly nor ignorantly, as your famous Mr. Hamilton learnedly remarks; but God has taught us to both reason and work according to existing circumstances, from cause to effect; nay, even as your great logicians would have it, a priori. And although five of our little bodies were sold in the markets of Jerusalem for two farthings, not one of us ever fell to the ground without our Father’s notice!”

There, that is about the kind of sermon our little bird would preach to the utter discomfiture of human wisdom, which, after all, is but “foolishness with God.”

Verily, and in conclusion, we declare that it is a libel upon the birds to say that they build their nests guided only by that nameless tendency signified by the common acceptation of the term “instinct.”

 
The humblest creature God has made
Fulfills some noble, wise design;
And, dowered rich with reason’s aid,
It boasts a lineage divine.
 

L. P. Veneen.

BERYL

This mineral species includes a number of varieties which are highly valued as gems. These are, besides Beryl itself, the gems emerald, aquamarine and golden beryl. Chrysoberyl, it may be noted, is not a variety of Beryl, but a distinct species.

While these gems all differ in color, they are the same mineral and are practically identical in composition, hardness and other properties. In composition they are a silicate of aluminum and glucinum, the percentage being, for normal beryl, 67 per cent of silica, 19 per cent of alumina and 14 per cent of glucina.

The beautiful green color of the emerald is probably due to a small quantity of chromium which it usually contains, though some authorities believe organic matter to be the coloring ingredient. To what substance the other varieties of the species owe their color is not known.

In hardness the varieties of Beryl differ little from quartz, the hardness being 7.5 to 8 in the scale of which quartz is 7. They are somewhat inferior therefore to such gems as topaz, sapphire and ruby in wearing qualities, although hard enough for ordinary purposes.

The specific gravity of Beryl is also about like that of quartz, ranging from 2.63 to 2.80; the specific gravity of quartz being 2.65. The varieties of Beryl are therefore relatively light as compared with other gems.

Beryl crystallizes in the hexagonal system. It usually occurs as six-sided prisms, commonly terminated by a single flat plane, but sometimes by numerous small planes giving a rounded effect and occasionally by pyramidal planes which cause the prism to taper to a sharp point.

The crystals sometimes grow to enormous size, exceeding those of any other known mineral. Thus, one found in Grafton, New Hampshire, was four and one-quarter feet in length and weighed two thousand nine hundred pounds. Another in the same locality is estimated to weigh two and one-half tons. In the museum of the Boston Society of Natural History and in the United States National Museum are exhibited single crystals also of great size. That in Boston is three and one-half feet long by three feet wide and weighs several tons. That in the National Museum weighs over six hundred pounds.

None of these crystals are of a high degree of purity or transparency, but the crystal planes at least of the prisms are well developed.

Beryl crystals have no marked cleavage except a slight one parallel with the base. Where broken, the surface shows what is called conchoidal fracture, i. e. it exhibits little rounded concavities and convexities resembling a shell in shape.

The mineral is quite brittle. Some emeralds even have the annoying habit of breaking of their own accord soon after removal from the mine. This can be prevented by warming them gradually before exposing them to the heat of the sun or other sudden heat.

Beryl and its varieties, like tourmaline, are dichroic, i. e. the stones exhibit different colors when viewed in different directions. This dichroism can sometimes be observed by the naked eye, but often not without the aid of the instrument known as the dichroscope. When seen it furnishes a positive means of distinguishing a true stone from any glass imitations.

The varieties of Beryl have none of the brilliancy of the diamond and therefore depend wholly on their body colors and their lustre for their beauty and attractiveness. Fortunately they exhibit these qualities as well by artificial light as by daylight.

Ordinary Beryl is a mineral of comparatively common occurrence, being often found in granitic and metamorphic rocks.

That of common occurrence is usually too clouded and fractured to be of use for gem cutting. There are many localities, however, where Beryls of gem quality occur.

The finest emeralds in the world come from Muso, a locality in the United States of Colombia, seventy-five miles N. N. W. of Bogota. It is a wild and inaccessible region and the mining of the gems is a precarious occupation. The emeralds occur according to Bauer in a dark, bituminous limestone which is shown by fossils to be of Cretaceous age. As emeralds in other localities occur only in eruptive or metamorphic rocks, it seems probable that the Muso emeralds have washed in from an older formation. The emerald bearing beds are horizontal, overlying red sandstone and clay slate. Calcite, quartz, pyrite and the rare mineral parisite are other minerals found associated with the emerald. The manner of working these emerald mines is thus described by Streeter:

“The mine is now worked by a company, who pay an annual rent for it to the government, and employ one hundred and twenty workmen. It has the form of a tunnel of about one hundred yards deep, with very inclined walls. On the summit of the mountains, and quite near to the mouth of the mine, are large lakes, whose waters are shut off by means of water-gates, which can be easily shifted when the laborers require water. When the waters are freed they rush with great rapidity down the walls of the mine, and on reaching the bottom of it they are conducted by means of an underground canal through the mountain into a basin. To obtain the emeralds the workmen begin by cutting steps on the inclined walls of the mine, in order to make firm resting places for their feet. The overseer places the men at certain distances from each other to cut out wide steps with the help of pickaxes. The loosened stones fall by their own weight to the bottom of the mine. When this begins to fill, a sign is given to let the waters loose, which rush down with great vehemence, carrying the fragments of rock with them through the mountain into the basin. This operation is repeated until the horizontal beds are exposed in which the emeralds are found.”

The next most prominent locality whence gem emeralds are obtained is that in Siberia on the river Tokovoya, forty-five miles east of Ekaterinburg. The emeralds here found are often larger than any yet obtained in South America, but they are not of so good quality. They occur in mica schist (see colored plate), and often associated with the mineral phenacite, chrysoberyl, rutile, etc.

Other localities whence emeralds are obtained are Upper Egypt (the source of those known to the ancients), the Heubachthal in Austria, and Alexander county, North Carolina, in our own country. The latter locality is no longer worked, but it has afforded a number of fine crystals.

Aquamarines and transparent Beryls are found in Siberia, India, Brazil, and in many localities in the United States. Dana describes an aquamarine from Brazil which approaches in size, and also in form, the head of a calf. It weighs two hundred and twenty-five ounces troy, is transparent and without a flaw. In the Field Columbian Museum is to be seen a beautiful cut aquamarine from Siberia more than two inches in diameter and weighing three hundred and thirty-one carats. Here is also the finest specimen of blue Beryl ever cut in the United States. It was found in Stoneham, Me., is rich sea green color in one direction and sea blue in another. It weighs one hundred and thirty-three carats. Numerous other Maine localities have furnished gem Beryls. Golden Beryls are found in Maine, Connecticut, North Carolina, Pennsylvania and other United States localities, as well as in Siberia and Ceylon. From them are obtained gems of rich golden color resembling topaz.

Beryl of a pale rose color is sometimes found, and when of good quality is cut for gem purposes, but it is of too rare occurrence to be important.

Emeralds seem to have been known and prized from the earliest times. They are mentioned in the Bible in several places, the earliest mention being in Exodus, where they are described as one of the stones making up the ephod of the high priest.

Their use in Egypt dates back to an unrecorded past and they frequently appear in the ornaments found upon mummies. Readers of Roman history will remember that the Emperor Nero used an emerald constantly as an eye glass.

The Incas, Aztecs and other highly civilized peoples of South America were found using these gems profusely for purposes of adornment and for votive offerings when first visited by the Spaniards. It was partly the desire to secure these gems which led Cortez and his followers, early in the sixteenth century, to undertake the conquest of Peru. Some of the emeralds wrested from the Incas by Cortez and brought to Spain are said to have been marvels of the lapidary’s art. One was carved into the form of a rose, another that of a fish with golden eyes, and another that of a bell with a pearl for a clapper.

During the years following Cortez’ conquest large quantities of emeralds were brought to Europe, and they became much more popular and widely distributed than previously. Joseph D’Acosta, a traveler of the period, says the ship in which he returned from America to Spain carried two chests, each of which contained one hundred pounds’ weight of fine emeralds.