Argentine Ornithology Volume Ii Part 18

Herons, of all birds, have the slowest flight; but though incapable of progressing rapidly when flying horizontally, when pursued by a Hawk the Heron performs with marvellous ease and grace an aerial feat unequalled by any other bird, namely, that of rising vertically to an amazing height in the air. The swift vertical flight with which the pursued ascends until it becomes a mere speck in the blue zenith, the hurried zigzag flight of the pursuer, rising every minute above its prey, only to be left below again by a single flap of the Heron's wings, forms a sight of such grace, beauty, and power, as to fill the mind of the spectator with delight and astonishment.

When the enemy comes to close quarters, the Heron instinctively throws itself belly up to repel the a.s.sault with its long, crooked, cutting claws. Raptorial species possess a similar habit; and the a.n.a.logous correlation of habit and structure in genera so widely separated is very curious. The Falcon uses its feet to strike, lacerate, and grasp its prey; the Heron to anchor itself firmly to its perch; but for weapons of defence they are equally well adapted, and are employed in precisely the same manner. The Heron, with its great length of neck and legs, its lean unballasted body, large wings, and superabundance of plumage, is the least suited of birds to perch high; yet the structure of the feet renders it perfectly safe for the bird to do so. Thus the Heron is enabled to sit on a smooth enamelled rush or on the summit of a tree, and doze securely in a wind that, were its feet formed like those of other Waders, would blow it away like a bundle of dead feathers.

Another characteristic of Herons is that they carry the neck, when flying, folded in the form of the letter S. At other times the bird also carries the neck this way; and it is, indeed, in all long-necked species the figure the neck a.s.sumes when the bird reposes or is in the act of watching something below it; and the Heron's life is almost a perpetual watch. Apropos of this manner of carrying the neck, so natural to the bird, is it not the cause of the extreme wariness observable in Herons?

Herons are, I think, everywhere of a shy disposition; with us they are the wildest of water-fowl, yet there is no reason for their being so, since they are never persecuted.

Birds ever fly reluctantly from danger; and all species possessing the advantage of a long neck, such as the Swan, Flamingo, Stork, Spoonbill, &c., will continue with their necks stretched to their utmost capacity watching an intruder for an hour at a time rather than fly away. But in the Herons it must be only by a great effort that the neck can be wholly unbent; for even if the neck cut out from a dead bird be forcibly straightened and then released, it flies back like a piece of india-rubber to its original shape. Therefore the effort to straighten the neck, invariably the first expression of alarm and curiosity, must be a painful one; and to keep it for any length of time in that position is probably as insupportable to the bird as to keep the arm straightened vertically would be to a man. Thus the Heron flies at the first sight of an intruder, whilst the persecuted Duck, Swan, or other fowl continues motionless, watching with outstretched neck, partic.i.p.ating in the alarm certainly, but not enduring actual physical pain.

Doubtless in many cases habits react upon and modify the structure of parts; and in this instance the modified structure has apparently reacted on and modified the habits. In seeking for and taking food, the body is required to perform certain definite motions and a.s.sume repeatedly the same att.i.tudes; this is most frequently the case in birds of aquatic habits. A facility for a.s.suming at all times, and an involuntary falling into, these peculiar att.i.tudes and gestures appears to become hereditary; and the species in which they are the most noticeable seem incapable of throwing the habit or manner off, even when placed in situations where it is useless or even detrimental. _Tringae_ rapidly peck and probe the mud as they advance; Plovers peck and run, peck and run again. Now I have noticed scores of times that these birds cannot possibly lay aside this habit of pecking as they advance; for even a wounded Plover running from his pursuer over dry barren ground goes through the form of eating by pausing for a moment every yard or so, pecking the ground, then running on again.

The Paraguay Snipe, and probably other true Snipes, possesses the singular habit of striking its beak on the ground when taking flight.

In this instance has not the probing motion, performed instinctively as the bird moves, been utilized to a.s.sist it in rising?

Grebes on land walk erect like Penguins and have a slow awkward gait; and whenever they wish to accelerate their progress they throw themselves forward on the breast and strike out the feet as in swimming.

The Glossy Ibis feeds in shallow water, thrusting its great sickle beak into the weeds at the bottom at every step. When walking on land it observes these motions, and seems incapable of progressing without plunging its beak downwards into imaginary water at every stride.

The Spoonbill wades up to its knees and advances with beak always immersed, and swaying itself from side to side, so that at each lateral movement of the body the beak describes a great semicircle in the water; a flock of these birds feeding reminds one of a line of mowers mowing gra.s.s. On dry ground the Spoonbill seems unable to walk directly forward like other birds, but stoops, keeping the body in a horizontal position, and, turning from side to side, sweeps the air with its beak, as if still feeding in the water.

In the foregoing instances (and I could greatly multiply them), in which certain gestures and movements accompany progressive motion, it is difficult to see how the structure can be in any way modified by them; but the preying att.i.tude of the Heron, the waiting motionless in perpetual readiness to strike, has doubtless given the neck its very peculiar form.

Two interesting traits of the Heron (and they have a necessary connexion) are its tireless watchfulness and its insatiable voracity; for these characters have not, I think, been exaggerated even by the most sensational of ornithologists.

In birds of other genera, repletion is invariably followed by a period of listless inactivity during which no food is taken or required. But the Heron digests his food so rapidly that, however much he devours, he is always ready to gorge again; consequently he is not benefited by what he eats, and appears in the same state of semi-starvation when food is abundant as in times of scarcity. An old naturalist has suggested, as a reason for this, that the Heron, from its peculiar manner of taking its prey, requires fair weather to fish--that during spells of bad weather, when it is compelled to suffer the pangs of famine inactive, it contracts a meagre consumptive habit of body, which subsequent plenty cannot remove. A pretty theory, but it will not hold water; for in this region spells of bad weather are brief and infrequent; moreover, all other species that feed at the same table with the Heron, from the little flitting Kingfisher to the towering Flamingo, become excessively fat at certain seasons, and are at all times so healthy and vigorous that, compared with them, the Heron is the mere ghost of a bird. In no extraneous circ.u.mstances, but in the organization of the bird itself, must be sought the cause of its anomalous condition; it does not appear to possess the fat-elaborating power, for at no season is any fat found on its dry starved flesh; consequently there is no provision for a rainy day, and the misery of the bird (if it is miserable) consists in its perpetual, never-satisfied craving for food.

316. ARDEA EGRETTA (Gm.).

(WHITE EGRET.)

+Ardea egretta+, _Scl. et Salv. Nomencl._ p. 125; _Durnford, Ibis_, 1877, p. 189 (Buenos Ayres), et 1878, p. 399 (Centr. Patagonia); _Gibson, Ibis_, 1880, p. 156 (Buenos Ayres); _White, P. Z. S._ 1882, p. 624 (Salta); _Barrows, Auk_, 1884, p. 271 (Entrerios, Pampas). +Ardea leuce+, _Burm. Syst. Ueb._ iii. p. 416; _id.

La-Plata Reise_, ii. p. 509. +Herodias egretta+, _Baird, Brew., et Ridgw. Water-B. N. A._ i. p. 23.

_Description._--White above and beneath; bill yellow; legs black; head not crested; side-plumes lengthened and decomposed: whole length 350 inches, wing 150, tail 60. _Female_ similar, but rather smaller.

_Hab._ North and South America.

The White Egret inhabits America from Nova Scotia to Patagonia, and is everywhere common, so that its breeding and other habits are very well known. On the pampas, owing to the absence of forests, its nesting-habits have been modified, for there it makes its nest amongst the reeds; as do also other species which elsewhere in America, North and South, build on trees. The following interesting account of a heronry on the pampas is from a paper by Mr. Gibson:--

"In November of 1873 I found a large breeding-colony of _Ardea egretta_, _A. candidissima_, and _Nycticorax obscurus_ in the heart of a lonely swamp. The rushes were thick, but had been broken down by the birds in a patch some fifty yards in diameter. There were from 300 to 400 nests, as well as I could judge; of these three fourths were of _A. egretta_, and the remainder, with the exception of two or three dozen of _N.

obscurus_, belonged to _A. candidissima_. Those of the first-mentioned species were slight platforms, placed on the tops of broken rushes, at a height of from two to three feet above the water, and barely a yard apart.

"The nests of _A. candidissima_ were built up from the water to the height of a foot or a foot and a half, with a hollow on the top for the eggs; they were very compactly put together, of small dry twigs of a water-plant. A good many were distributed amongst those of _A. egretta_; but the majority were close together, at one side of the colony, where the reeds were taller and less broken.

"The nests of _N. obscurus_ much resembled the latter in construction and material; but very few were interspersed amongst those of the other two species, being retired to the side opposite _A. candidissima_, on the borders of some channels of clear water; there they were placed amongst the high reeds, and a few yards apart from each other.

"The larger Egrets remained standing on their nests till I was within twenty yards of them, and alighted again when I had pa.s.sed. In this position they looked much larger than when flying. The smaller Egrets first flew up onto the reeds above the nests, and then immediately took to flight, not returning; while _N. obscurus_ rose and sailed away, uttering a deep _squawk, squawk_, long before one came near the nest.

"At one side of the colony a nest of _Ciconia maguari_, with two full-grown young, seemed like the reigning house of the place.

"It certainly was one of the finest ornithological sights I ever saw: all around a wilderness of dark green rushes, rising above my head as I sat on horseback; the cloud of graceful snow-white birds perched everywhere, or reflected in the water as they flew to and fro overhead; and the hundreds of blue eggs exposed to the bright sunlight.

"_A. egretta_ and _A. candidissima_ lay four eggs each, though the former rarely hatches out more than three. _N. obscurus_ lays and hatches out three. The eggs of all three species are of the same shade of light blue."

317. ARDEA CANDIDISSIMA, Gm.

(SNOWY EGRET.)

+Ardea candidissima+, _Scl. et Salv. Nomencl._ p. 125; _Durnford, Ibis_, 1877, p. 189 (Buenos Ayres); _Gibson, Ibis_, 1880, p. 158 (Buenos Ayres); _Barrows, Auk_, 1884, p. 271 (Entrerios).

+Garzetta candidissima+, _Baird, Brew., et Ridgw. Water-B. N. A._ i. p. 28. +Ardea nivea+, _Burm. La-Plata Reise_, ii. p. 509.

_Description._--White above and beneath; adult with a long occipital crest of decomposed feathers and dorsal plumes lengthened; lores and toes yellow; bill black, yellow at base; legs black, behind yellowish at the lower part: whole length 240 inches, wing 95, tail 40. _Female_ similar.

_Hab._ North and South America.

The Snowy Egret is common on the pampas, and throughout all the warm portions of North and South America; but does not range so far south as _Ardea egretta_. It is a very pretty bird in its dazzling white plumage, and is more active and social in its habits than most Herons, being usually seen in small flocks, and often a.s.sociates with Ibises and other aquatic species. An account of its breeding-habits has already been given.

318. ARDEA CaeRULEA, Linn.

(BLUE HERON.)

+Ardea caerulea+, _Burm. La-Plata Reise_, ii. p. 509. +Florida caerulea+, _Baird, Brew., et Ridgw. Water-B. N. A._ i. p. 43.

_Description._--Dark bluish plumbeous; head and neck purplish chestnut; bill blue, blackish at the end; feet black: whole length 200 inches, wing 90, tail 36. _Female_ similar.

_Hab._ North and South America.

This well-known North-American Heron extends far to the south. Natterer obtained examples at several places in the province of Sao Paolo, Brazil. Dr. Burmeister tells us that he met with it on the Rio Negro, and also near Mercedes in the Argentine Republic.

319. ARDEA SIBILATRIX, Temm.

(WHISTLING HERON.)

+Ardea sibilatrix+, _Temm. Pl. Col._ 271; _Scl. et Salv. Nomencl._ p.

125; _iid. P. Z. S._ 1869, p. 634 (Buenos Ayres); _White, P. Z.

S._ 1882, p. 624 (Salta); _Barrows, Auk_, 1884, p. 271 (Entrerios).

_Description._--Above grey; cap, occipital crest, and wing-feathers greyish black; large patch behind the eye rufous; upper wing-coverts rufous, striped with grey: beneath white, breast tinged with yellowish; bill reddish, tip black; feet black: whole length 220 inches, wing 115, tail 45, tarsus 34. _Female_ similar.

_Hab._ South America.

This is a beautiful bird, with plumage as soft as down to the touch. Its colours are clear blue-grey and pale yellow, the under surface being nearly white. In some specimens that I have obtained the rump and tail-coverts had a pure primrose hue. There is a chestnut mark on the side of the head; the eye is white, and the legs dark green in life.

Azara named this Heron "_Flauta del Sol_" (flute of the sun), a translation of the Indian term _Curahi-remimbi_, derived from the popular belief that its whistling notes, which have a melodious and melancholy sound, prophesy changes in the weather.