Madras Journal of Literature and Science/Series 1/Volume 6/On the Structure and Habits of the Elanus Melanopterus

by Brian Houghton Hodgson

VIII.—On the Structure and Habits of the Elanus Melanopterus.—By B. H. Hodgson, Esq. British Resident in Nipal.

To the Editor of the Madras Journal.

Sir,—The following details relative to the structure and habits of Elanus Melanopterus will prove interesting to all persons engaged in the noble attempt to classify birds according to their natural affinities, or, in other words, according to their essential conformation and manners.

Whether this attempt will succeed in the hands of such as, for the moat part, have no adequate means of knowing more of habits and economy, than can be gleaned from the random notices of merely casual observers, nor any more of structure than can be elaborated from dry skins, remains to be seen. But I return to my subject.

MILVINÆ.
Genus. Elanus.
Species. Elanus Melanopterus.

The Chanwa and Chanwa Musaher of Hindosthan. Form. The female is 13 inches long, by 35 in expanse of wings, and 8½ oz. in weight. The male is about 1 inch smaller, and seldom weighs above 7½ oz. Both have the same aspect. The following is a detail of the dimensions of a male:—

inches. parts.

Tip bill to tip tail 12 ½

Bill, length, from gape 1 1/16

Bill, length, from brows 0 13/26

Bill, basal height... 0 10/(illegible text)

Bill, basal width 0 15/16

Length of tail 5 (illegible text)

Expanse of wings 34 0

Length of a closed wing 10 ½

Length of tarsus, to sole 1 7/16

Length of central toe 1 {{illegible/16

exclusive of talons.

Length of inner fore toe 0 13/16

Length of outer fore toe 0 11/16

Length of hind toe..... 0 9/16

Length of hind talon (straight) 0 11/16

The bill, from the gape, is as long as the head, that is, actually long: but from the brow it is more distinctly short: a peculiarity caused by the width of the mouth and by the advanced position of the frontal plumes. Both the bill and the head, from the nares to the occiput, are distinguished by great breadth; but the bill, before the nares, is much compressed and feeble. The bill is slightly curved from the base; its hook is long and sharp; its upper mandible has a conspicuous accipitrine festoon; and its lower one is rather abruptly truncated but not notched. The cere is of mean size, and is nearly hid by soft curling hairs which radiate from the four angle of the eyes and clothe the lores and orbits: the nostrils are oval, longitudinal, lateral, with a full and free membranous edge on the upper margin. The eye is large and is furnished with a conspicuous salient opercule. The wings are very ample, and usually exceed the tail by 1½ inch. Next to their length, their chief feature is the breadth and softness of the webs or vanes of the feathers. The second quill is invariably the longest; and the third is longer than the first, the former being about (illegible text), and the latter ⅝, of an inch less than the second. The primes exceed the tertials by more than a third of the entire length of the former. The first quill is moderately notched on the inner vane, about 1½ inch from its point: but the notch is less strong and more remote than in Falco. The scapulars are usually about 1½ inch shorter than the tertials. The tail is short, and, like the wings, noticeably soft, as is, indeed, the whole plumage. The tail is, upon the whole, nearly even; but there is a slight gradation from below in the extreme lateral feathers, and another from the centre above. The latter seldom exceeds half an inch, but still the tail may be said to be somewhat forked, though there be scarcely a trace of the divaricating structure, even in the extreme feathers. Shortness and thickness are the characteristics of the legs and feet : but the thickness is of that sort which the vulgar call 'gumminess'—not nervous strength. The tarsi are half plumed in front; their residue, and the toes, being very finely reticulated, with the exception of three digital scales next to each talon. The toes are short, unequal, and cleft, but the outer one, though free, can only act in front. The chief feature of the digits is the excess in length of the inner over the outer fore one. The central one has the average superiority over the others in length; and the hind one is just half as long as the central, or somewhat short but broad and stout. All the digits have nearly the same thickness. The soles of the feet are full and rounded, soft and unbailed. The talons are sufficiently large, strong and acute; the inner and hind being equal; the central as long almost but feebler ; and the outer fore, much the smallest. All the talons are rounded below, but none of them are compressed.

The ear, as well as the eye, is very noticeably large; and the gape reaches to the centre of the eye or more. The breadth of the head, and of the bill near it, have been already noticed; and these features, together with the amplitude of the wings, and the shortness of the tail and feet, seem to indicate (in the language of Mr. Swainson) a Natatorial or Fissirostral type. And, as there cannot, I suppose be two such types in the circle of the Mil vine?, it is difficult to imagine how Nauclerus and Elanus can continue distinct in this single circle.

But what the manners of Elanus? The birds of this genus are not, in India, migratory : they breed on (not in) trees, laying usually from 3 to 5 eggs in April, May, and rearing commonly from 3 to 4 young. The Chanwa or black wing quests chiefly in the morning and evening, feeding upon small birds, insects and mice. It does not usually seize upon the wing, though its hunting be, for the most part, by continuous questing. Commonly it is seen skimming the cultivation, like a Circus, occasionally poising itself on the wing for the purpose of getting a distincter view of some mouse, small bird or insect which has stirred on its beat and upon which, when clearly perceived, it stoops perpendicularly with the speed of lightning. After a while, it will resort to some low roost, and, when relieved, commence another excursion, or perchance sit and watch there for its prey. Its forward flight is easy, low, and silent, but very effective in evolution when exertion is required to capture such nimble game as mice, which constitute its ordinary food.

It frequently whips off insects from the stalks of standing grain, after the manner of the Brahmani Cheel or Halioetus(!) Pondicerianus; and this feat is, of course, accomplished on the wing. I have also seen the Chanwa pursue cuckoos and sparrows with uncommon energy, but I never witnessed it strike a bird in the air. Like the type of Circus, however, the Chanwa doubtless can, and sometimes does, seize its feathered prey on the wing. So that its manners are, upon the whole, sufficiently Fissirostral : perhaps as much so as its Raptorial affinities will admit of. Analogies and affinities are very fine abstract terms, which the quiet Orientals would be puzzled to deal with. But, as these words really import no more than remote and near resemblance of form and habits, one can hardly resist the presumption that (strongly as habits illustrate form), so observant and ancient a people as the Indians have probably reached some general conclusions as to the true relations of the animate beings of their own country, such as may be, oft-times, more worthy of a philosophical attention than the conclusions upon the same matters that have been elaborated in Europe out of dry skins, by dint of inference from structure so seen, to habits wholly unknown.

Now, it is remarkable enough that the people have, for ages past, been wont to approximate the Slant to the Harriers, but still without confounding the two. Is there any warrant for this approximation? It would seem so : for, both are twilight questers, flying in the same manner and seeking the same prey (mice). Both have large eyes and ears, soft plumage, long wings, wide gapes, large nostrils nearly hid by radiating hairs, bills much compressed and feeble before the cere, but furnished with a long sharp hook and an accipatrine festoon. In several of these common attributes there is an equal and conspicuous tendency towards the Strigine model, which tendency seems to give fresh authority to that approximation of the two groups to each other, so long familiar to the people of India, though bat yesterday, and still dimly, perceived by the towering ken of European science!