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Show 1873.] DISTRIBUTION OF ASIATIC BIRDS. 657 The Himalaya mountains were divided by Hodgson (see J. A . S. B. 1835) into three zones of elevation, each of which has a more or less distinct fauna; and as these three faunas are characteristic of three different zoological provinces, they are no doubt very natural ones. The lowest, from the level of the plains up to about 3000 or 1000 feet, including the Terai, is a region of dense jungle, marshy plains at the foot of the hills, steep forest-clad spurs and deep valleys, which preserve the tropical character of their fauna and flora for a long distance into the interior. It is rich in all the most characteristic Indo-Malayan genera, such as Hornbills, Barbets, Kingfishers, Fruit-Pigeons, Bulbuls, and Woodpeckers, the latter in particular being so numerous that, out of eighteen species found in Sikim, all but three occur in the lowest zone. A few representatives of other genera which are more numerously represented in the Malay sub-region also occur, as Hierax eutolmus, Harpactes hodgsoni, Psarisomus dalhousiee, Pitta cucullata, Hydrornis nipalensis, and Poly-plectron chinquis (not found west of the Tista). Along the edge of the forest, and where cultivation has encroached ou its limits, some of the commoner birds of the plains are found, whilst on the rivers and marshes many wading birds and waterfowl spend the winter. These, however, rarely enter the hills, though they must pass over them at the period of their migrations. Many Warblers which breed in the upper and middle zones descend during the cold weather to the lower hills and plains, wandering over a great part of India, and in some cases, perhaps, breeding in the higher mountains of the peninsula. Several species of Ruticillinee, Motacillince, and Cuculidce also descend to this zone in winter ; but if we exclude the wading and water birds, it has not so many species as the zone above it, the numbers being, as well as I can estimate them, about 130 to 260. In this zone the fauna is very much the same in character as that of the Malabar coast, Burmah, and Assam, and, though possessing many peculiar species of birds, has hardly any genera which are not also found in those countries. The transition from the lower zone to the middle is both gradual and irregular, depending much on the peculiarities of different valleys and localities. For instance, at an elevation of 3000-4000 feet in the valley of the little Rungeet, and in that part of the Tista valley which is at a distance from the plains, many of the tropical forms are replaced by birds of the middle zone ; but it is on the whole undoubtedly true that the birds of the middle zone from 3000-4000 to 10000-11000 feet have a decidedly different character. Here the forest becomes dark and gloomy; oaks, magnolias, and rhododendrons densely covered with mosses and fern replace the saul trees, plantains, and giant bamboos of the lower region. In many places the mountains from about 7000 to 9000-10,000 feet are covered by a forest of hill bamboo, so dense that it is impossible to go off the beaten path without clearing a way with the knife. Among these small bamboos, and in the rhododendron-woods which are such a characteristic feature of the middle zone, are found P R O C . Z O O L . S o c - 1 8 7 3 , N o . XLII. 42 |