SHEATHBILL, a bird so-called by T. Pennant in 1781 (Gen. Birds, ed. 2, p. 43) from the horny case which ensheaths the basal part of its bill. It was first made known from having been met with on New-Year Island, off the coast of Staten Land, where Cook anchored on New Year's eve 1774. A few days later he discovered the islands that now bear the name of South Georgia, and there the bird was again found—in both localities frequenting the rocky shores. On his third voyage, while seeking some land reported to have been found by Kerguelen, Cook in December 1776 reached the cluster of desolate islands now generally known by the name of the French explorer, and here, among many other kinds of birds, was a Sheathbill, which for a long while no one suspected to be otherwise than specifically identical with that of the western Antarctic Ocean; but, as will be seen, its distinctness has been subsequently admitted.
The Sheathbill, so soon as it was brought to the notice of naturalists, was recognized as belonging to a genus hitherto unknown, and J. R. Forster in 1788 (Enchiridion, p. 37) conferred upon it, from its snowy plumage, the name Chionis, which has most properly received general acceptance, though in the same year the compiler Gmelin termed the genus Vaginalis, as a rendering of Pennant's English name, and the species alba. It has thus become the Chionis alba of ornithology. It is about the size of and has much the aspect of a Pigeon; its plumage is pure white, its bill somewhat yellow at the base, passing into pale pink towards the tip. Round the eyes the skin is bare, and beset with cream-coloured papillae, while the legs are bluish-grey. The second or eastern species, first discriminated by G. Hartlaub (Rev. zoologique, 1841, p. 5; 1842, p. 402, pl. 2) as C. minor, is smaller in size, with plumage just as white, but having the bill and bare skin of the face black and the legs much darker. The form of the bill's “sheath” in the two species is also quite different, for in C. alba it is almost level throughout, while in C. minor it rises in front like the pommel of a saddle. The western and larger species gathers its food, consisting chiefly of sea-weeds and shellfish, on rocks at low water; but it is also known to eat birds' eggs. As to the flavour of its flesh, some assert that it is wholly uneatable, and others that it is palatable. Though most abundant as a shorebird, it is frequently met with far out at sea, and has once been shot in Ireland. It is not uncommon on the Falkland Isles, where it breeds. C. minor of Kerguelen Land, Prince Edward Island, Marion Island and the Crozets, is smaller, with pinkish feet. The eggs of both species, though of peculiar appearance, bear an unmistakable likeness to those of oyster-catchers, while occasionally exhibiting a resemblance to those of the tropic-birds.
The systematic position of the sheathbills has been the subject of much hesitation, but they are now placed in a special family, Chionidae, amongst Charadriiform birds (see Birds), not far from the curious little group of “seed-snipes” of the genera Thinocorys and Attagis, which are peculiar to certain localities in S. America and its islands. (A. N.)
- A strange fallacy arose that this case or sheath was movable. It is absolutely fixed.
- Doubtless some of the earlier voyagers had encountered it, as Forster suggests (Descr. animalium, p. 330) and Lesson asserts (Man. d'ornithologie, ii. 343); but for all practical purposes we certainly owe its discovery to the naturalists of Cook's second voyage. By some error, probably of transcription, New Zealand, instead of New-Year Island, appears in many works as the place of its discovery, while not a few writers have added thereto New Holland. Hitherto there is no real evidence of the occurrence of a Sheathbill in the waters of Australia or New Zealand.
- In the Falkland Isles it is called the “Kelp-Pigeon,” and by some of the earlier French navigators the “Pigeon blanc antarctique.” The cognate species of Kerguelen Land is named by the sealers “Sore-eyed Pigeon,” from its prominent fleshy orbits, as well as “Paddy-bird”—the last doubtless from its white plumage calling to mind that of some of the smaller Egrets, so-called by the English in India and elsewhere.
- Lesson (loc. cit.) cites a brief but correct indication of this species as observed by Lesquin (Lycée armoricain, x. 36) on Crozet Island, and, not suspecting it to be distinct, was at a loss to reconcile the discrepancies of the latter's description with that given of the other species by earlier authors.