' Long-tailed Duck 115 
ness be called a semi-eclipse plumage. The result of my investigations on the change that 
takes place is as follows : — 
During August the male Long-tailed Duck completely changes the wing, tail, back, and 
black portion of the mantle and black breast-band, these parts being replaced by the new 
winter plumage. The head, neck, and upper mantle, showing worn and faded plumage 
feathers, remain until shed at the end of September. The elongated scapulars are shed 
and not renewed until late September, but in late July a considerable number of new 
blackish and brown feathers come into the upper scapulars and mix with the old worn 
summer plumage feathers, whilst a number of new dark-grey feathers, similar to those 
worn by the Scaup, Tufted Duck, and Golden-Eye male in eclipse, come into the flanks and 
remain until shed again in early October. 
The reason of this, I take it, is that since Nature abhors sudden changes of colour from 
dark to light, whilst the landscape is still under the warm colours of summer and autumn, 
the male Long-tail only renews those parts of its plumage to the full winter dress which 
are directly in harmony with its surroundings, adding, however, temporary feathers, as it 
were, to carry it over the three temperate months when it hides in the shadows of banks 
or rocky inlets. Thus all the dark parts of its plumage are renewed once, and once only, 
and the light parts which would be noticeable are delayed by a temporary makeshift until 
such a time as concealment is no longer necessary. In point of fact the winter dress of 
the male Long-tail, who lives amongst the white-lipped waves of troubled waters, is as 
suitable a dress from the point of view of assimilation to the surroundings as the rich 
dress of summer or the sombre black of autumn. I conclude, therefore, that it is not 
correct to call the brown plumage of April the "eclipse dress," but rather think that it 
should be known as the "summer plumage." 
Length (including elongated tail-feathers), 22-26 inches ; wing, 8.8 inches ; bill, i inch ; 
tarso-metatarsus, 1.25 inch; the beak at the tip and base black, the middle portion being 
of a red rose colour ; feet, slate ; webs, dusky-black ; irides, hazel. 
The top of the bill of the male Long-tailed Duck joins the skull in a somewhat peculiar 
manner. The highest point of the bill is extended slightly above the part of the long struc- 
ture, and there is a distinct dip in the front of the crown, lower than the highest part of the 
bill, before it rises to the crown. Mr. Hugh Wormald, who first called my attention to this 
point, emphasises the fact that the top of the bill stands out clearly as a ridge above the 
feathers, but this can only be observed on close examination, and does not seem apparent 
in life. 
Immature Female. — In first plumage the immature female closely resembles the 
young male, except that the colour is somewhat paler. They are also easily recognised by 
October by the incoming feathers of the respective sexes. In the case of the young female 
the advance of plumage is somewhat slower than that of the male, and she only obtains a 
few of the winter dress feathers. In April the greater part of the adult summer plumage 
is assumed, but there is little or no change on the back, breast, and lower parts, whilst the 
wings and tail are not shed at all until the principal moult in July and August. The young 
female then gradually assumes her winter dress, which is complete in October. She is thus 
adult at sixteen months, and will pair and breed the following summer. 
A dult Female. — Winter plumage : Crown and hinder parts of the cheeks, dark brown ; 
