(2288) Mergus merganser orientalis.
The Eastern Goosander.
Mergus orientalis Gould, P. Z. S., 1845, p. 1 (Amoy, China). Merganser castor. Blanf. & Oates, iv, p. 409 (part.).
Vernacular names. None recorded.
Description. The Eastern Goosander differs from the "Western bird principally in being distinctly smaller; in addition the male has the black on the inner secondaries and scapulars greater in extent, the lower back and rump are paler grey and more thickly freckled with white; the crest is also usually thinner and more scanty bat this is not always the case, the salmon-pink tinge on the lower plumage is very pronounced.
Colours of soft parts as in the typical form.
Measurements. Wing, 243 to 284 mm., 189 to 257 mm.; culmen, 49 to 54 mm., 40 to 47 mm.
Males in eclipse, young males and females differ from the adult male in the same way as they do in the preceding bird.
Nidification. The Eastern Goosander breeds on the larger lakes of the Himalayan plateaus in May and June. Osmaston says it breeds regularly in Ladak, on the lakes in Rupshu and the Pangong Lake in late June, and that it also breeds on the Indus at about 13,000 feet. In Tibet it breeds in great numbers between 12,500 and 15,000 feet on or near most of the larger lakes. Here the birds breed in holes in cliffs and steep, high banks, sometimes at considerable distances from the water. Two nests obtained for me near Hram-Tso Lake were made in hollows or crevices in rocks in a crumbling cliff. There appears to have been no material in either of the hollows, though there was a good deal of rubbish, moss, earth etc. filling up the bottoms below the eggs, which rested in very thick beds of down which completely buried them. The down when sent home was half, the part which formed the walls, clean and fluffy; the other half, forming the bed, full of moss, dirt etc. and required much cleaning and baking. When cleaned it became a pale grey, of the same very fluffy character as that of the Common Goosander Each nest contained seven fresh eggs, one being taken on the 7th and the other on the 8th of June. The eggs are like those of M. m. merganser but smaller. Twenty eggs average 64.6 x 44.8 mm.: maxima 67.0 X 44.2 and 64.0 x 45.0 mm.; minima 62.8 x 44.8 and 64.0 x 43.5 mm.
Habits. The Eastern Goosander is a not very common resident from Afghanistan and Baluchistan to Kashmir, occurring in corresponding numbers in Winter on the plains immediately adjacent. From Ladak to Setchuan it is a very common bird and in Winter visits the foot-hills of Behar, Sikkim, Bhutan and Asssm in very large numbers, though these diminish rapidly as the plains extend into Bengal, Orissa and Burma. In Assam Goosanders associate mostly in small flocks of a dozen to thirty or forty birds, but these collect in the early mornings and evenings and together wend their way down to their fishing-ground, so that several hundred may be seen passing up and down a river in a very short time. They seem to be equally at home in the deep slowly-moving pools or in the wildest torrents and it is a most beautiful sight to see a party of these birds playing in either kind of water. At other times they may be seen fishing, a whole party working in concert, forming a wide semi-ring and driving the fish into a backwater. Although the birds dash hither and thither, both on and under water, with almost incredible speed, the formation is never broken and the end is always a holocaust of small fish after the shallows are reached. The gorging ended, the birds sit on some sand-bank so full that when disturbed they have to disgorge before moving. They run well on land in a very upright position but if pressed tumble about in all directions and, normally, they prefer to shuffle along on their breasts down to the water. They are very wary birds and even when replete one or more are always on sentry duty to warn the flock on the approach of danger.
In Assam they keep entirely to swiftly-flowing rivers but after they reach the land of sluggish, muddy waters they take to the clearer lakes and ponds if such are to be found.