Scaup Duck 
65 
with often beak yellowish ; under mandible, yellow." The female young in down is 
said by Naumann to be distinguished by a greenish tinge on the under parts. 
Immahtre Male. — In first plumage in September the young male and female are 
very similar, except that the upper part of the wings of the young male, instead of being 
uniform brown, is slightly vermiculated with greyish-white; the head, neck, chest, nape, 
and mantle are dull brown, and in both sexes there is a space of dull whitish-brown 
about half-an-inch broad behind the upper mandible. The brown chest feathers are above 
edged with sandy-brown, and below, where they join the under parts, edged with white ; 
lower belly, vent, and under tail-coverts, mottled with pale-brown ; under parts, white : 
back and rump, very dark brown, the back feathers being finely vermiculated with whitish- 
grey ; primaries as in adults, only paler; secondaries, white and edged with dark brown, 
the dark marking increasing as they join the wing-coverts, which are very dark brown ; 
upper parts of wings, dark greyish-brown, and slightly vermiculated ; tail, dark brown. 
By the middle of October there is a very considerable advance in the plumage of the 
young male ; the dark brownish-white space on the lores is also interspersed with blackish- 
green feathers, which extend all over the head and neck ; the brown mantle and back are 
moulted to grey, heavily vermiculated with dark brown ; whilst the scapulars show the first 
adult white feathers more finely barred. There is a very distinct colour change in the 
pale-brown flanks, which, although not yet moulted, now show pale-grey vermiculations ; 
as yet there is no change in the chest. At the end of October the first black feathers appear 
on the lower chest, and in some instances the young males have nearly lost the whitish 
feathers on chin and lores. So the plumage goes on advancing through November and 
December, principally on the back, scapulars, mantle, and upper chest, whilst the head 
and neck is often complete in the end of the latter month. These advances are, however, 
by no means regular, and are doubtless due to the early or late hatching of the young bird, 
for I have often shot young males in February, which have not yet cast the last white 
feathers of the lores. 
The lower chest is generally the last part of the immature plumage to be cast, and this 
portion of the plumage is often still unshed by the beginning of May, whilst all the rest 
of the plumage is similar to that of the adult male (see Fig. 8). The wings too are also 
variable, some young males moulting all the upper parts in March and April, others 
not doing so until the principal moult in July and August. The young male Scaup do 
not pair and breed as some of the other members of the genus do in their first spring, 
but remain in parties on the breeding grounds, shedding the last of their immature plumage 
in July, and assuming an eclipse similar to the adult male. They are therefore only 
mature at twelve months. In the second spring the male pairs and breeds, but its full 
beauty is not assumed until the third season. 
Adult Male. — Head, neck, upper breast, nape, and mantle, black; the head and upper 
neck glossed with green and purple ; back and scapulars white, and narrowly barred with 
black, line markings being fainter as spring approaches ; lower breast, under parts, and 
flanks, white ; vent and last flank feathers vermiculated with fine black lines ; rump 
and under tail-coverts, black ; tail, dark brown ; wing-coverts, black, finely vermiculated 
with white; primaries, blackish-brown, with whitish area on the inner web; secondaries, 
white, and margined with a black band, sometimes flecked with white ; upper wing-coverts 
VOL. I. I 
