(2287) Mergus merganser merganser.
Mergus merganser Linn., Syst. Nat., 10th ed.; i, p. 129 (1758) (Sweden). Merganser castor. Blanf. & Oates, iv, p. 469.
Vernacular names. None recorded.
Description. - Male. Whole head, upper neck and long crest of narrow feathers black glossed with metallic green, showing purple in a bright light; the centre of the chin and throat gloss-less ; lower neck and underparts white; upper back glossy black; lower back, rump and upper tail-coverts grey, much vermiculated with white, especially on the sides ; the tail-coverts have dark shafts and sometimes paler edges; tail silvery-brown, paler and more grey on the under aspect; primaries and outer secondaries very dark brown ; inner secondaries white, with a narrow edging of black on the outer webs; greater secondary coverts white with black bases; primary coverts and edge of wing black; remaining coverts white; outer scapulars white with narrow black margins; the inner scapulars all black, one or two of those next the white ones being tipped with white and having irregular narrow white edgings.
In life the whole of the white underparts are suffused with a beautiful rosy-salmon, often very pronounced on the breast; this colour unfortunately fades very quickly after death and is therefore not apparent in museum specimens.
Colours of soft parts. Iris carmine or deep red, sometimes tinged with brown in the younger birds; bill vermilion, the nail black and sometimes the culmen rather dusky, especially in the non-breeding season ; legs and feet bright vermilion.
Measurements. Wing 283 to 298, once 300 mm.; tail 104 to 115 mm,; tarsus about 46 to 51 mm.; culmen 55 to 63 mm.
Female. Chin and throat white: the lores albescent-rufous; rest of head and neck dull rufous, the crown more brown;, primaries and first few secondaries dark brown; the next few white and the innermost grey with dark margins; upper parts grey, rather mottled in appearance and the upper tad-coverts with dark shafts; tail grey-brown with darker, browner shafts; some of the scapulars very dark brown; the lesser and median wing-coverts mottled grey and greyish-white; sides of neck and whole lower surface white, the flanks striped with grey.
Colours of soft parts as in the male but all duller; the irides. always brown.
Measurements. Wing 251 to 272 mm,; culmen 45 to 53 mm.
Young males are like the female but have shorter crests whilst the markings on the flanks are brown instead of grey; the dark and light of the scapulars contrast more. According to Witherby the scapulars of the young male are much longer than in the young female.
Colours of soft parts. Iris brown; bill orange-red, the tip and culmen dusky and the under mandible sometimes fleshy or yellowish-red; the legs and feet are orange-red or sometimes even orange-brown.
Males in eclipse plumage resemble the female but retain the white wing-coverts; generally the centre of the neck and breast are white; the soft parts are less brilliantly coloured than in the breeding-season.
Nestling. Upper parts brown or grey-brown, the crown and neck tinged with rufous and the rump and back darker and more brown than the sides; a white patch on the wings and a second an each side of the rump ; a third joining the white of the underparts on each side of the back ; a dark streak through the eye ; a small white patch above the eye, indefinite and often tinged tawny.
Distribution. Iceland and North Europe to Kamschatka; moving in Winter South to Northern Africa and South Asia. In India this bird occurs in Sind and on the Mekran coast but all the specimens occurring in the Himalayas, sub-Himalayas and Northern India appear to belong to the smaller Eastern race. A specimen from Oude has a wing of 298 mm. and must be of the Western race and another, equally big, from Bombay is the same.
Nidification. The Goosander breeds from the end of April in the most Southern latitudes to the middle or even end of June in the most Northern. The bird chooses as a site either a natural hollow in a tree, a hole in rocks, a rabbit-burrow or just a hollow in long grass or heather. The nest itself is of the slightest; when in a hole there is often nothing beyond the thick lining of greyish-white down, whilst even when made in grass and heather it consists merely of the beaten-down herbage with a few scraps of dry grass added. The eggs number six to fourteen, most often seven or eight and are a creamy-white to pale buff, distinctly lighter and paler than those of the Red-breasted Merganser. One hundred and fifty eggs average 68.3 x 47.1 mm.: maxima 74.5 X47.5 and 70.0 x 49.0 mm.; minima 63.0 x 45.0 and 68.0 X 41.0 mm.
In Finland, where all the small farmers keep a series of boxes round their farms for the ducks to breed in, this species often occupies them. The same is the case in the small islands round about the entrance to Helsingfors, where, however, the bird is not common.
Habits. This Goosander during the non-breeding-season is more of a sea than freshwater bird. It lives almost entirely by fishing and when thus employed comes a long way up rivers and streams and sometimes does an enormous amount of damage to fisheries. It is a most voracious feeder and during a day will easily devour and digest 100 small fish, for it generally confines itself to those of three to five inches, though when hungry it will take and swallow fish of much larger size. Under pressure Gossanders will also eat frogs, insects, larvae, worms etc. They are among the most expert of divers and swimmers. Normally they swim rather high in the water but they can at will sink themselves so that only the back is out of water or merely the head and neck. They often fish in company and then unite in forming a semicircle, driving the fish before them into a shallow, where it is more easy to capture them. They rise off the water slowly, splashing along the surface for some way, but once in the air can fly at a great pace. Their ordinary voice is a low, harsh croak but during the courting-season the male has a plaintive, soft whistle, which is also uttered by the female and young.