[321.] ARDETTA INVOLUCRIS (Vieill.).
(VARIEGATED HERON.)
[Plate XVII.]
Ardetta involucris, Scl. et Salv. Nomencl. p. 125; iid. P. Z. S. 1869, p. 634; Hudson, P. Z. S. 1875, p. 624 (Buenos Ayres); Durnford, Ibis, 1877, p. 189, et 1878, p. 62 (Buenos Ayres); Gibson, Ibis, 1880, p. 159 (Buenos Ayres); Barrows, Auk, 1884, p. 271 (Entrerios).
Description.—Above pale fulvous; narrow stripe on the nape black; front, stripe on the back of the neck, bend of wing, and outer secondaries chestnut-red; back striped with black; wing-feathers dark cinereous with red tips: beneath paler, nearly white on the belly; neck, breast, and flanks with brown stripes, darker in the centres; bill yellow; feet brown: whole length 13·0 inches, wing 5·0, tail 1·5.
Hab. Paraguay and Argentina.
The Variegated Heron is the least of the family to which it belongs, its body being no bigger than that of the Common Snipe; but in structure it is like other Herons, except that its legs are a trifle shorter in proportion to its size and its wings very much shorter than in other species. The under plumage is dull yellow in colour, while all the other parts are variegated with marks of fuscous and various shades of brown and yellow. The body is extremely slim, and the lower portion of the neck covered with thick plumage, giving that part a deceptively massive appearance. The perching faculty, possessed in so eminent a degree by all Herons, probably attains its greatest perfection in this species, and is combined with locomotion in a unique and wonderful manner. It inhabits beds of rushes growing in rather deep water; very seldom, and probably only accidentally, does it visit the shore, and only when driven up does it rise above the rushes; for its flight, unlike that of its congeners, is extremely feeble. The rushes it lives amongst rise, smooth as a polished pipe-stem, vertically from water too deep for the bird to wade in; yet it goes up to the summit and down to the surface, moving freely and briskly about amongst them, or runs in a straight line through them almost as rapidly as a Plover can run over the bare level ground. Unless I myself had been a witness of this feat, I could scarcely have credited it; for how does it manage to grasp the smooth vertical stems quickly and firmly enough to progress so rapidly without ever slipping down through them?
The Variegated Heron is a silent solitary bird, found everywhere in the marshes along the Plata, as also in the reed-beds scattered over the pampas. It breeds amongst the rushes, and lays from three to five spherical eggs, of a rich lively green and beautiful beyond comparison. The nest is a slight platform structure about a foot above the water, and so small that there is barely space enough on it for the eggs, which are large for the bird. When one looks down on them they cover and hide the slight nest, and being green like the surrounding rushes they are not easy to detect.
When driven up the bird flies eighty or a hundred yards away, and drops again amongst the rushes; it is difficult to flush it a second time, and a third time it is impossible. A curious circumstance is that where it finally settles it can never be found. As I could never succeed in getting specimens when I wanted them, I once employed some Gaucho boys, who had dogs trained to hunt young Ducks, to try for this little Heron. They procured several specimens, and said that without the aid of their dogs they could never succeed in finding a bird, though they always marked the exact spot where it alighted. This I attributed to the slender figure it makes, and to the colour of the plumage so closely assimilating to that of the dead yellow and brown-spotted rushes always found amongst the green ones; but I did not know for many years that the bird possessed a marvellous instinct that made its peculiar conformation and imitative colour far more advantageous than they could be of themselves.