Savannah Finch, or Yellow-shouldered Bunting (Fringilla savanarum, Gmel.) Nuttall, Manual, part i. p. 494.
Bill short, conical, acute; upper mandible slightly convex in its dorsal outline, angular, and encroaching a little on the forehead, of the same breadth as the lower, with sharp and inflected edges; lower mandible also inflected on the edges; gap-line slightly deflected at the base. Nostrils basal, roundish, open, concealed by the feathers. Head rather large, neck short, body full. Feet of moderate length, slender; tarsus covered anteriorly with a few longish scutella, acute behind; toes free, scutellate above, the lateral ones nearly equal; claws slender, compressed, acute, slightly arched, that of the hind toe elongated.
Plumage soft and blended, slightly glossed. Wings shortish, curved, rounded, the first and second primaries longest, the third scarcely shorter; the secondaries long, but less so than in the Henslow Bunting, which belongs to the same group. Tail short, small, rounded, slightly emarginate, of twelve narrow, tapering feathers.
Bill flesh-coloured beneath, dusky above. Iris dark brown. Feet light flesh-coloured. The general colour of the upper parts is light greyish-brown, mixed on the neck with ash-grey tints, the central parts of the feathers brownish-black, the margins of those of the back bright chestnut. The upper part of the head brownish-black, with a longitudinal central line of brownish-white. Secondary coverts dusky, margined with greyish-white; along the flexure of the wing the small feathers are bright yellow, whence the name of the species. Quills wood-brown, margined with pale yellowish-brown. Tail-feathers of the same colour, the outermost much paler. The under parts pale yellowish-grey, the breast of a richer tint, being of a light yellowish-brown, its sides anteriorly spotted with brownish-black.
Length 4 10⁄12 inches, extent of wings 8; bill along the ridge 5½⁄12, along the edge ½; tarsus ⅔, middle toe a little more than ⅔, hind toe 7⁄12.
This species forms part of a group more allied to the Buntings than to the Finches, and composed of Henslow's Bunting or Finch, the Savannah Finch, and the Yellow-winged Sparrow. They are all very closely allied, so that it is somewhat difficult to distinguish them.
Let us compare the Yellow-winged Sparrow in the first place, with the Henslow Bunting, described at [p. 360 of Vol. I].
In Henslow's Bunting the bill is smaller, and has the margin less sinuous; the tarsi are shorter, being only 7⁄12 (erroneously ⅔ in the description), while those of the present species are ⅔. The feet of the latter are also stronger, and the toes a little longer. The colouring of the upper parts is very similar; but the present species has a distinct white line along the middle of the head, whereas the other has the same part of the general olivaceous tint of the hind-neck, the quills are differently coloured on their margins, and while the present species is unspotted on the breast and sides, the other is distinctly streaked.
But besides these differences the feathers present others still more decisive. The tail of Henslow's Bunting is 2⅛ inches long, graduated, with narrower feathers, which taper to a point, while that of the Yellow-winged Sparrow is only 1 10⁄12, rounded, much stronger, with broader (though still very narrow) feathers, having a narrow rounded point. Then in the first the secondaries are so long as to be only 2⁄12 shorter than the longest primary, whereas in the second they are ½ inch shorter. In the first the third quill is longest, while in the second the first exceeds the others, although in neither is there any great difference between the first three quills in length.
But the Yellow-winged Sparrow is much more closely allied to the Savannah Finch than to Henslow's Bunting.