42 
billed the cuiinen line is almost straight, whereas in the Common Loon it is slightly arched 
(Figure 78, compare with Figure 77). This will probably separate all specimens except 
those that have not quite acquired their growth. 
From the Arctic or the Red-throated Loons size is sufficient distinction. 
Field Marks. Large size and conspicuous yellowish white bill are said to make excel- 
lent field marks for the adult. 
Nesting. Practically unknown, but probably similar to that of the other Loons. 
Distribution. The northwest Arctic coast and the great lakes of Mackenzie, probably 
nesting on the ponds of the tundras where no one goes in summer time. 
The migrations and breeding range of the Yellow-billed Loon are 
among our unsolved ornithological problems. It evidently winters in some 
numbers, at least occasionally, on the south Alaskan coast, but we have no 
British Columbia records. It should be looked for there with care, but 
identified with caution. 
9. Arctic Loon (Including Black- throated Loon and Pacific Loon). Gama 
arctica. L, about 24. Similar to, but smaller than, the Common Loon, from which 
it differs in colour principally on the crown and hindneck 
(Figure 79), which is dark grey on the forehead but gradually 
becomes a light smoky ash down the hindneck. 
Distinctions. General colour as above, in adults. Juveniles 
are distinguished from the Common Loon by their distinctly 
smaller size and from the Red-throated Loon, with which they 
agree closely in that particular, by the general coloration; in 
juvenility and winter plumages, by the lack of fine V-shaped 
white specklings on the back. 
Field Marks. The grey hindneck and black throat and 
foreneck should make excellent field marks in life. In juvenile 
plumage, size separates from the two big Loons and, when deter- 
minable, the unspeckled back from the Red-throated. 
Nesting. Similar to the other Loons. 
Distribution. In summer an inhabitant of the far north from lake Athabaska north- 
ward. In migration rarely down through the prairies, but wintering in numbers on the 
British Columbia coast. 
S UBSPECIES The Arctic Loon is a circumpolar species. The common American 
form is the Pacific Loon Gavia arctica padfica , given in the Check-list as a full species, 
but now generally acknowledged to be only subspecifically distinct from the Black-throated 
Loon of Europe that has crown and hindneck uniformly coloured. A third, Asiatic race, 
G. artica viridigularis, has been described recently and should be looked for on the west coast. 
It is characterized by having green instead of purple reflections on the throat. 
Figure 79 
Arctic Loon; scale, 
11. Red-throated Loon. Gavia slellala. L, 25. This is similar in Bize to the 
Arctic Loon and decidedly smaller than the Common Loon. It is without the intensely 
black and white colour pattern of either. The head and neck of 
the adult are of soft, even slate grey with a maroon-red throat patch 
(Figure 80). The back is an even greyish brown, the rest of the 
body being white. 
Distinctions. The colour pattern is absolutely distinctive in 
the adult. Juveniles and winter birds are without the grey neck 
and red throat, these colours being replaced by white which con- 
tinues unbrokenly from the underparts, producing a coloration 
very similar to the Arctic except that the back is sprinkled with small 
white specklings instead of grey feather edgings. The species is 
so much smaller than the two large Loons that there can be little 
confusion with them. 
Field Marks. The grey head and neck, red throat patch, and 
evenly coloured back make good field marks for the adult. In 
juvenility and in winter, size should separate it from all except the Arctic Loon; when it can 
be seen the finely speckled back is conclusive. 
Nesting. Similar to the preceding species. 
Distribution. Ranges over the whole of Canada, scarce in the interior, more common 
on either coast. Breeds north of regular settlement to the Arctics. 
Figure 80 
Red-throated Loon; 
scale, about |. 
