ZOSTEROPS,[1] originally the scientific name of a genus of birds founded by N. A. Vigors and T. Horsfield (Trans. Linn. Society, xv. p. 235) on an Australian species called by them Z. dorsalis, but subsequently shown to be identical with the Certhia caerulescens, and also with the Sylvia lateralis, previously described by J. Latham. The name has been Anglicized in the same sense, and, whether as a scientific or a vernacular term, applied to a great number of species[2] of little birds which inhabit for the most part the tropical districts of the Old World, from Africa to most of the islands in the Indian and Pacific Oceans, and northwards in Asia through India and China to the Amur regions and Japan.
The birds of this group are mostly of unpretending appearance, the plumage above being generally either mouse-coloured or greenish olive; but some are varied by the white or bright yellow of their throat, breast or lower parts, and several have the flanks of a more or less lively bay. Several islands are inhabited by two perfectly distinct species, one belonging to the brown and the other to the green section, the former being wholly insular. The greater number of species seem to be confined to single islands, often of very small area, but others have a very wide distribution, and the type-species, Z. caerulescens, has largely extended its range. First described from New South Wales, where it is very plentiful, it had been long known to inhabit all the eastern part of Australia. In 1856 it was found in the South Island of New Zealand, when it became known to the Maories by a name signifying “Stranger,” and to the British as the “Blight-bird,”[3] from its clearing the fruit-trees of a blight. It soon after appeared in the North Island, where it speedily became common, and thence not only spread to the Chatham Islands, but was met with in considerable numbers 300 miles from land, as though in search of new countries to colonize. In any case it is obvious that this Zosterops must be a comparatively modern settler in New Zealand.
All the species of Zosterops are sociable, consorting in large flocks, which only separate on the approach of the pairing season. They build nests — sometimes suspended from a horizontal fork and sometimes fixed in an upright crotch — and lay (so far as is known) pale blue, spotless eggs, thereby differing wholly from several of the groups of birds to which they have been thought allied. Though mainly insectivorous, they eat fruits of various kinds. The habits of Z. caerulescens have been well described by Sir W. Buller (Birds of New Zealand), and those of a species peculiar to Ceylon, Z. ceylonensis, by Col. Legge (B. Ceylon), while those of the widely ranging Indian Z. palpebrosa and of the South-African Z. capensis have been succinctly treated by Jerdon (B. India, ii.) and Layard (B. South Africa) respectively.
It is remarkable that the largest known species of the genus, Z. albigularis, measuring nearly 6 in. in length, is confined to so small a spot as Norfolk Island, where also another, Z. tenuirostris, not much less in size, occurs; while a third, of intermediate stature, Z. strenua, inhabits the still smaller Lord Howe's Island. A fourth, Z. vatensis, but little inferior in bulk, is found on one of the New Hebrides; the rest are from one-fifth to one-third less in length, and some of the smaller species hardly exceed 312 in.
Placed by some writers, if not systematists, with the Paridae (see Titmouse), by others among the Meliphagidae (see Honey-Eater), and again by others with the Nectariniidae (see Sunbird), the structure of the tongue, as shown by H. F. Gadow (Proc. Zool. Society, 1883, pp. 63, 68, pl. xvi. fig. 2), entirely removes it from the first and third, and from most of the forms generally included among the second. It seems safest to regard the genus, at least provisionally, as the type of a distinct family—Zosteropidae—as families go among Passerine birds. (A. N.)
- ↑ The derivation is ζωστήρ-ηρος and ὤψ, whence the word should be pronounced with all the vowels long. The allusion is to the ring of white feathers round the eyes, which is very conspicuous in many species.
- ↑ In 1883 R. B. Sharpe (Cat. B. Brit. Museum, ix. pp. 146–203) admitted 85 species, besides 3 more which he had not been able to examine.
- ↑ By most English-speaking people the prevalent species of Zosterops is commonly called “ White-eye ” or “ Silver-eye.”