THE BLUE YELLOW-BACKED WARBLER.
Sylvia americana, Lath.
PLATE XV. Male and Female.
This pretty species enters Louisiana from the south as early as spring appears, at the period when most insects are found closer to the ground, and more about water-courses, than shortly after, when a warmer sun has invited every leaf and blossom to hail the approach of that season when they all become as brilliant as nature intended them to be. The little fellow under your eye is then seen flitting over damp places, such as the edges of ponds, lakes, and rivers, chasing its prey with as much activity and liveliness as any other of the delicate and interesting tribe to which it belongs. It alights on every plant in its way, runs up and down it, picks here and there a small winged insect, and should one, aware of its approach, fly off, pursues it and snatches it in an instant.
I have placed a pair of these Warblers on a handsome species of Iris. This plant grows in the water, and in the neighbourhood of New Orleans, a few miles below that city, where I found it abundantly, and in bloom, in the beginning of April. Several flowers are produced upon the same stem. I have not met with it anywhere else, and the name of Louisiana Flag is the one commonly given it.
As soon as the foliage of the forests begins to expand, the Blue Yellow-backed Warbler flies to the tops of the trees, and there remains during the season, gleaning amongst the leaves and branches, in the same active manner as it employed when nearer the ground, not leaving off its quick and short pursuit of small insects on the wing. When on the branches, it frequently raises its body (which is scarcely larger when stripped of its feathers than the first joint of a man's finger) upwards to the full length of its legs and toes, and is thus enabled to seize insects otherwise beyond its reach.
Its flight is that of a true Sylvia. It ascends for a while in a very zigzag manner, and returns suddenly to nearly the same place, as if afraid to encounter the dangers of a prolonged excursion. I do not think it ever flies to the ground. It hops sidewise as well as straight forward, hangs like a Titmouse, and searches the cups of even the smallest flowers for its favourite insects.
I am inclined to think that it raises two broods in a season, having seen and shot the young on the trees, in Louisiana, early in May, and again in the beginning of July. The nest is small, formed of lichens, beautifully arranged on the outside, and lined with the cottony substances found on the edges of different mosses. It is placed in the fork of a small twig, and so far towards the extremity of the branches as to have forced me to cut them ten or fifteen feet from it, to procure one. On drawing in the branch carefully to secure the nest, the male and female always flew toward me, exhibiting all the rage and animosity befitting the occasion. The eggs are pure white, with a few reddish dots at the larger end, and were in two instances four in number. It was several years before I discovered one of these nests, so small are they, and so difficult to be seen from the ground.
This species is found throughout the United States, and may be considered as one of the most beautiful of the birds of those countries. It has no song, but merely a soft, greatly prolonged twitter, repeated at short intervals. It returns southward, out of the Union, in the beginning of October.
Adult Male. Plate XV. Fig. 1.
Bill longish, depressed at the base, nearly straight, tapering to a point. Nostrils basal, oval, half concealed by the feathers. Feet of ordinary length, slender; tarsus compressed, covered anteriorly with a few long scutella, acute behind, longer than the middle toe; toes scutellate above, free; claws arched, slender, compressed, acute.
Plumage blended, glossy. Wings longish, little curved, the first quill longest. Tail slightly forked, of ordinary length, the twelve feathers rather narrow and obtuse. A few longish bristles at the base of the upper mandible.
Bill brownish-black above, yellow beneath. Iris dark brown. Feet and claws dusky. Front and lore black. Head and back part of the neck bright rich blue, including the eye, above and beneath which is a slight streak of white. Back yellowish-green; rump pale blue. Quills blackish, margined externally with bright blue, of which colour are the wing-coverts, the tips of the first two rows of which are white, forming two bands of that colour on the wings. Tail-feathers blackish, the outer webs blue, a white spot on the inner webs of the three outer, towards the end. Throat whitish, spotted with yellow; a lunulated blackish spot on the lower neck in front; breast yellow, spotted with orange; the rest of the under parts yellowish, fading into white on the abdomen and under tail coverts.
Length 4⅙ inches, extent of wings 6½; bill along the ridge ⅓, along the gap ½; tarsus ¾.
Adult Female. Plate XV. Fig. 2.
Beak and feet of the same colour. Upper parts similarly coloured but paler, the frontal band wanting. Throat, fore neck and breast, yellow, without the orange spots, or black lunule. The other parts as in the male, but fainter.
Length 4 inches.
The Coppery Iris, or Louisiana Flag.
"Beardless, the stem equal in height to the leaves, which are broadly ensiform, the stigmas linear and short, all the petals emarginate, reflected, and obovate, the inner shorter, the capsules large and hexagonal. Found on the banks of the Mississippi near New Orleans. Flowers of a beautiful copper colour, veined with purple."