LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 69 
Plumages.—The downy young is plainly colored; the short thick 
down, with which it is covered, is “light seal brown” on the back, 
“clove brown” on the sides, head, and neck, and “ light drab” on the 
breast and belly. A specimen in the American Museum, in New 
York, collected in northeastern Siberia on September 16, 1901, shows 
the change from the downy stage into the first winter plumage. This 
is similar to the corresponding plumage of the common loon, but this 
species can be recognized by its smaller size. In the first winter 
plumage the under parts are pure white, the throat and sides of the 
head are largely white, more or less streaked or mottled with dusky, 
and the upper parts are dark blackish brown; the characteristic fea- 
ture of this plumage is that the feathers of the back are broadly 
margined with light gray, giving it a scaly appearance. This 
plumage is worn during the winter and part of the following spring; 
when the bird is nearly a year old it begins'to show progress toward 
maturity by a partial molt. Macgillivray (1852) quotes Temminck’s 
description of this stage in the European bird, as follows: 
The young, when a year old, have the head and hind neck pale gray; the 
throat and fore part of the neck white; but on the throat and sometimes on 
the fore part of the neck, there appear some violet-black feathers mixed with 
white feathers; the longitudinal streaked band of the sides of the neck begins 
to form; the streaks of the lower part of the neck equally appear, and some 
black feathers without spots, appear on the back, rump, and sides. 
A complete, first, postnuptial molt takes place in the latter part of 
the summer, producing a second winter plumage which is similar to. 
and probably indistinguishable from the adult winter plumage. 
During the winter and spring further progress toward maturity is 
made, -producing a second nuptial plumage, of which Macgillivray 
(1852) gives Temminck’s description, as follows: 
At the age of 2 years the gray of the head and nape become deeper, and 
assume a blackish tint, but only on the forehead; the violet black of the throat 
and forepart of the neck appear, but are variegated with some white feathers ; 
the longitudinal bands are formed; the feathers of the sides and of the upper 
part of the back, the scapulars, and wing coverts assume the white bands and 
spots; the upper mandible becomes blackish, but its base, as well as a portion 
of the lower mandible, are still of a gray color. 
Perhaps some individuals may require another year to reach the 
full maturity of plumage, but probably most birds may be consid- 
ered adult and acquire their full plumage at an age of 2 years. 
Certainly during the third autumn, and probably during the second, 
the adult winter plumage is assumed. This differs from the first 
winter plumage in being uniformly dark blackish brown above, with- 
out any lighter margins on the feathers of the back; the throat and 
lower half of the head are also purer white, without any dusky mark- 
ings. The prenuptial molt involes practically all of the contour 
feathers and the postnuptial molt is complete. 
