Kitabı oku: «A History of North American Birds, Land Birds. Volume 3», sayfa 31

Haliaëtus leucocephalus.

Mr. MacFarlane found these Eagles breeding on Lockhart River, latitude 67° 30′, but does not regard it as abundant in that locality, and from the information he has received from the Indians, he presumes latitude 68° to be its extreme northern range. In the following year, 1862, this supposition was in part confirmed by his finding a pair breeding on the same river, near its junction with the Anderson, in latitude 68° north. Mr. B. E. Ross states that it ranges to the Arctic Circle, and is numerous around Great Slave and Bear Lakes. It proved to very common at Sitka, where Bischoff obtained a number of specimens.

Dr. Cooper, during his journey northward to the 49th degree, found this one of the most abundant birds of the Falcon tribe in Washington Territory, particularly along the Columbia River. It is a constant resident in the Territory, and is said to lay its eggs as early as February. He saw large numbers along the Columbia, sitting on some log or cliff over the water. He never met with it about high mountain tops nor on the plains east of the Rocky Mountains.

Dr. Newberry met with this Eagle in the interior of Northern California, along the Sacramento and San Joaquin Rivers. He found it very common at the Cascades of the Columbia, at the Falls of the Willamette, and still more abundant about the chain of lakes in the Klamath basin, and also in the Cascade Range, among the mountain lakes, and wherever fish was attainable. They exhibited little shyness, and were easily brought within rifle range.

In Florida, Mr. Allen found this bird very common, breeding as early as January. It was very abundant on the upper St. John’s, and especially so at Lake Monroe. It is also equally common in Texas, according to Dresser, especially near the headwaters of some of the rivers. He was told by his guide, Westfall, that in passing a distance of forty miles he had noticed eight nests. It also breeds on the Altacosa. Dr. Woodhouse found these birds, but nowhere very abundant, from the Gulf of Mexico to the Pacific, along his entire route, and Dr. Coues observed them near Fort Whipple.

The statements of Temminck that this Eagle has been taken accidentally in Central Europe, Switzerland, and Germany, and also that it breeds in Northwestern Europe, are not now credited; and more recent scrutiny of these supposed facts cast discredit upon them, and show that there is no well-authenticated instance of its having been detected in Europe.

The White-headed Eagle appears to be equally well adapted by nature for the endurance of heat or cold, and is apparently indifferent to either. Its residence is influenced only by its abundance of food, especially that of fish; and it seems to matter very little whether that plenty is procurable within the Arctic Circle or on the coast and rivers of Florida and Texas. In places like the Falls of Niagara, where the stream is ever liable to contribute the remains of animals destroyed by the descent of the torrent, this Eagle is especially abundant. Unscrupulous, greedy, voracious, not select in its choice of food, and capable of providing for itself when necessity compels, we find this not altogether unsuitable emblem of our country now enacting the tyrant and robber and plundering the Fishhawk of the fruits of its industry, now sharing with the Raven and the Vulture the dead salmon of the Columbia, and in other places diving for and catching its own fish. The impetuosity and skill with which it pursues, overtakes, and robs the Fishhawk, bearing off a fish it has just taken, must be witnessed to be appreciated; and the swiftness with which the Eagle can dart down upon and seize the booty, which the Hawk has been compelled to let fall, before it reaches the water, is not the least wonderful feature of this striking performance. On the banks of the Columbia, where there are no Fishhawks to depend upon, this bird finds an easy subsistence on the vast numbers of dead and dying salmon which abound; and in Florida Mr. Allen has observed it dive and catch its own fish. This is also confirmed by the statements of other naturalists. Wilson also accuses this Eagle of destroying great numbers of young pigs in the Southern States, young lambs, and even sickly sheep; and in one instance it attempted to carry off a child, which was only saved by its dress giving way.

The White-headed Eagle breeds along the Atlantic coast from the St. Lawrence to Florida, and thence westward to Mexico along the coast and among the tributaries of the Gulf. In the interior it breeds as far north as the Arctic Circle.

Richardson states that it abounds in the watery districts of Rupert’s Land, and a nest may be looked for within every twenty or thirty miles. Each pair appropriates a certain range of country, on which they are said to suffer no intruders of their own species to encroach; but the nest of the Osprey is often placed at no great distance from that of the Eagle. Some of the voyagers had the curiosity to visit an Eagle’s nest, which was built on the cleft summit of a balsam poplar, of sticks, many of them as thick as a man’s wrist. It contained two young birds, well fledged, with a good store of fish in a very odoriferous condition. While the men were climbing the tree, the female parent hovered close around, and threatened an attack on the invaders; but the male kept aloof, making circles high in the air.

In California, where the rocky coast is destitute of convenient trees, the White-headed Eagle resorts to rocky cliffs as the safest and most convenient places for nesting. We have the authority of Richardson for the same deviation from its usual resort to trees in parts of the fur-countries where the latter are wanting. The climate apparently exerts a certain influence, though not so much as might be supposed. In the Southern States it nests seven weeks earlier than in Maine, in both of which regions it is resident throughout the year. Farther north, where the severity of the cold, by closing the ponds and rivers with solid ice, places their food beyond their reach, and where they are only visitants in the warmer season, they, of course, nest still later, for the reason that they do not reach these regions until after the breeding season of more southern birds of the species.

In the extreme Southern States, as in California, the White-headed Eagle breeds as early as February. In Maine, the general impression has been that the eggs are not deposited before May, and at a still later period in the more northern portions of the United States. More recent observations show this to be incorrect, and that these birds breed at a much earlier season of the year. Mr. Audubon speaks of having once shot a female on her eggs, near the Mississippi, as early as the 17th of January. Dr. Gambel found White-headed Eagles nesting on the cliffs along the shores of the Pacific in February and March.

Having occasion to visit the State of Maine in April, 1856, near the Damariscotta River, the banks of which stream are frequented by these birds on account of the abundance of fish, I was informed that a pair had constructed a nest in a neighboring wood, which they had occupied for several successive years. The previous season (1855), late in May, my informant had climbed a tree in the immediate neighborhood, commanding a full view of the nest. It then contained young nearly grown. From this statement I was led to conclude that there was no time to be lost if we would secure the eggs before hatching. We accordingly visited the nest on the 27th of April, and found it situated on a tall pine, at least sixty feet from the ground. The tree stood in a swampy wood, within a few rods of the stage road, and not more than half a mile from the village of Damariscotta. It contained no limbs or branches to facilitate ascent for at least the distance of thirty feet, and the trunk at the base was from six to nine feet in circumference, rendering it impossible to mount the tree by the aid only of the hands and feet. My assistant was, however, drawn up, by means of a rope fastened round his body, to a height where the branches of the tree rendered the remainder of the ascent comparatively easy. While he was ascending, we observed several Eagles flying over our heads, but at a great height. One only approached us; but, as soon as we were noticed, the bird made a precipitate retreat. It was apparently conveying food to the nest, and was not at first aware of our presence; after which it hovered at a distance, uttering hoarse, disagreeable cries of displeasure, not unlike the imperfect barking of a dog. No attempt was made to molest or interrupt the man as he ascended to, or after he had reached, the nest. We found, when he had climbed to the nest, that the female had been sitting upon it all the while, and only left when the unwelcome caller was near enough to have reached her with his hands. She too flew over the man’s head in somewhat close proximity, uttering frequent cries of distress, but made no effort whatever to attack him.

The nest was found to contain no egg, and but a single bird, apparently about a fortnight old. It was some six or seven inches in length, its weight between one and two pounds, and its head and claws disproportionately large. It was covered uniformly with a thick, close, and soft downy plumage, which was of a clean deep straw-color. There was not the least admixture of gray or brown. The young bird was completely helpless, and uttered almost constant cries for food. It ate readily whenever fish or meat was offered it, but was unable to support itself upon its legs. It was taken to my host’s house, where it was well cared for, and for a while, with careful attention, it did well and grew apace, manifesting a most inordinate and insatiable appetite.

The nest was described to me by my assistant as a platform between five and six feet in diameter, and at least four in thickness. It was constructed of regular layers of large sticks, each several feet in length, and from an inch to an inch and a half in thickness. Its surface was perfectly flat, and was “finished off,” to use his expression, with tufts of grass, dry leaves, mosses, lichens, small twigs, etc., etc. He found in it, by the side of the young Eagle, four or five large eels, each of which was about two feet in length, showing that the parent birds provide liberally for their own wants and those of their young.

Estimating the age of the young Eagle at ten days, and allowing four weeks for incubation, and at least one week’s interval between the deposition and the commencement of the parent bird’s sitting upon it, we have very nearly the exact period at which the egg was laid, March 13.

This occurred at the coldest period of the season, when the ground was covered with snow to an unusual depth, and when the thermometer indicated a temperature at that time frequently as low as 15° below zero.

The nest is usually of great size, composed of sticks from three to five feet in length, pieces of turf, weeds, and moss. Its diameter is about five feet, and its depth is not unfrequently as great. In the warmer localities, where it breeds, the pair usually frequent the same nest throughout the year, and make it their permanent place of resort. This is also true, probably, wherever this Eagle remains throughout the year. Mr. T. H. Jackson, of West Chester, Pa., informs me that he met with three fresh eggs of this species in Maryland, on the 11th of February, 1871.

The eggs are usually two, sometimes three or four, in number; they are nearly spherical, equally rounded at either end, and more or less granulated on their surface. Their color is a dull white, unspotted, but often stained by incubation to a dirty white or a light soiled drab. Two eggs in my collection present the following measurements: Length 3 inches, breadth 2.75; length 2.88 inches, breadth 2.80. The first was obtained in New Jersey by Alexander Wilson, the ornithologist; the latter by Dr. Trudeau, in Louisiana.

Another, taken from a nest in Texas by Dr. Heermann, measured 2.80 by 2.20 inches. A fourth, from Sitka, measures 2.75 by 2.25 inches. These measurements, so far as they may be taken as typical, exhibit but little variation in size between the most northern and the most southern specimens.

Several nests were met with and the eggs taken by Mr. MacFarlane near Anderson River. They were generally built in high trees not far from river-banks. In a few instances the parents made hostile demonstrations when their nests were robbed, but generally kept at a safe distance, uttering loud and discordant sounds. The nests were built of dry sticks and decayed branches, and lined with deer’s hair, mosses, hay, and other similar soft materials.

Mr. Dall was informed by the Indians that this species breeds among the Alaskan mountains on inaccessible cliffs. This statement, however, may have had reference to the Golden Eagle.

Falco communis (Europe), p. 138.

Family CATHARTIDÆ.—The American Vultures

Cathartidæ, Gray, 1842.—Huxley, P. Z. S. 1867, p. 463. Cathartinæ, Lafr. 1839. Sarcorhamphidæ, Gray, 1848. Gryphinæ, Reich. 1850.

The characters of this family have been given in sufficient detail (III, 1), so that a short diagnosis, showing its most readily observable peculiarities, will here be sufficient.

Char. Whole head, and sometimes the neck, naked; eyes prominent, and not shaded by a superciliary shield. Cere much elongated, much depressed anteriorly below the very arched culmen; nostrils longitudinal, horizontal, the two confluent or perforate. Middle toe very long, and the hind one much abbreviated. A web between the base of the inner and middle toes.

The family Vulturidæ,⁹⁴ as long recognized, included all the naked-headed, carrion-feeding Raptores of both the Old and the New World. The later researches of science, however, have shown the necessity of separating the Vultures of the latter continent from those of the former, and ranking them as a distinct family, while at the same time the Old World Vultures are found to be merely modified Falconidæ. The resemblance between the Cathartidæ and the vulturine Falconidæ is merely a superficial one of analogy, and not one of affinity. Being the scavengers of the countries they inhabit, the latter thus perform the same office in nature as the former, and for adaptation to a similar mode of life their external characters are modified to correspond. Close, however, as is the external resemblance between the two groups, their osteological structure and internal anatomy is entirely different.

The Cathartidæ differ from the Vulturinæ⁹⁵ as to their external structure in the following particulars, the osteological structure being entirely different in the two groups, the latter being like the Falconidæ in all the characters which separate the latter family from the Cathartidæ.

Cathartidæ. Nostrils horizontal, perforate; a well-developed web between the inner and middle toes, at the base.

Vulturinæ. Nostrils vertical, not perforate; no trace of web between inner and middle toes.

In habits, the Cathartidæ resemble the vulturine Falconidæ of the Old World. “They lack the strength and spirit of typical Raptores, and rarely attack animals capable of offering resistance; they are voracious and indiscriminate gormandizers of carrion and animal refuse of all sorts,—efficient and almost indispensable scavengers in the warm countries where they abound. They are uncleanly in their mode of feeding; the nature of their food renders them ill-scented, and when disturbed they eject the fetid contents of the crop. Although not truly gregarious, they assemble in multitudes where food is plenty, and some species breed in communities. When gorged, they appear heavy and indisposed to exertion, usually passing the period of digestion motionless, in a listless attitude, with their wings half spread. But they spend most of the time on wing, circling high in the air; their flight is easy and graceful in the extreme, and capable of being indefinitely protracted. On the ground, they habitually walk instead of progressing by leaps. Possessing no vocal apparatus, the Vultures are almost mute, emitting only a weak hissing sound.” (Coues.)

The Cathartidæ all belong to the tropical and warm temperate portions of the continent, only one species (Rhinogryphus aura) extending its range as far as the border of the colder regions. The famous Condor (Sarcorhamphus gryphus) of the Andes and the equally large California species (Pseudogryphus californianus) are among the largest birds of flight in the world, being exceeded in size by none, and rivalled but by one or two of the Vultures of the Eastern Hemisphere.

The following diagnoses based upon the external structure are sufficient to characterize the very well-marked genera and subgenera of this family. The distinctive osteological characters which accompany these external features afford still more decided differences, and are illustrated by the figures.

S. gryphus, ♂, Chile. ¼ nat. size.

S. papa, ♀, Mazatlan. ¼ nat. size.

Genera and Subgenera

A. Crop naked. Male with a fleshy crest, or lobe, attached to the top of the cere. Bill very robust and strong, its outlines very convex; cere much shorter than the head.

1. Sarcorhamphus. Entire neck bare; nasal cavity entirely open; posterior claw very thick and strongly curved. Tail even.

Sexes different, the female lacking any fleshy caruncles, or appendages, on the head and neck. Frontal lobe, or fleshy crest of male, extending from the anterior border of the cere to the middle of the crown; throat with a median wattle, or “dewlap”; side of the neck with a somewhat convoluted or twisted caruncle, extending from the side of the occiput obliquely downward, across the neck to near the lower extremity of the gular wattle; lower part of the foreneck with a pendent fleshy appendage. Plumage beginning below the neck by a crescentic ruff of soft white down, or cottony feathers, around the posterior portion. Primaries longer than the secondaries; front of the tibio-tarsal joint feathered … Sarcorhamphus.⁹⁶

Sexes alike, the female possessing the caruncular appendages of the head as well as the male. Frontal lobe attached to only the middle portion of the cere, above the nostril; throat without a median wattle; side of the neck without any caruncles; no appendage on the foreneck; auricular region with longitudinal corrugations, and occiput densely haired. Plumage beginning below the neck by a ruff of broad, well-developed, normal feathers. Primaries not longer than the secondaries. Front of the tibio-tarsal joint naked … Cathartes.⁹⁷

B. Crop feathered. Male without a fleshy crest, or other appendages, on the head. Bill less robust, variable as to strength, its outlines only moderately convex; cere nearly equal to the head in length. Sexes alike.

a. Entire neck bare; plumage commencing abruptly in a ruff of lanceolate, or penicillate feathers, these continued on the breast and abdomen. Head much elongated, the upper outline a slightly convex plane, the forehead depressed below the level of the very elevated dorsal outline of the cere. Posterior claw very thick and strongly curved.

2. Pseudogryphus. Nostril occupying only the posterior third of the nasal orifice, its anterior end acute. Bill weak, the terminal hook only slightly developed, the mandibles broader than deep, the lower as deep as the upper. Head and neck without corrugations or caruncles. Tarsus slightly longer than the middle toe; fourth or fifth quill longest; extremities of the quills reaching to or beyond the end of the tail. Tail even. (P. californianus.)

b. Only the upper half, or less, of the neck bare; plumage commencing gradually with normal, broad feathers; feathers of breast and abdomen broad and normal. Head only moderately elongated, the upper outline irregular, the forehead elevated above the dorsal outline of the cere. Bill strong, the terminal hook well developed. Posterior claw weaker, less curved.

3. Rhinogryphus. Nostril occupying the whole of the nasal cavity, its anterior end broadly rounded; cere as deep as broad, the upper and lower outlines divergent posteriorly, the former considerably arched; lower mandible much less deep than the upper. Skin of the neck without corrugations; a semicircular tuft of antrorse radiating bristles in front of the eye. Wing very long, the primaries reaching to or beyond the end of the tail. Tail much rounded. (R. aura and R. burrovianus.)

4. Catharista. Nostril occupying only the posterior half of the nasal cavity, its anterior end contracted and acute; cere depressed, much wider than deep, its upper and lower outlines parallel, the former not perceptibly arched; lower mandible as deep as the upper; skin of the neck transversely corrugated; no tuft of bristles in front of the eye. Wing short, the primaries reaching scarcely to the middle of the tail. Tail even, or slightly emarginate. (C. atratus.)