40 
The*Loons are probably even better divers than the Grebes, but they 
rise less easily from the water, and unless there is a good breeze that they can 
face, require a long splashing start over the surface before being wing-borne. 
Economic Status. Their food is composed almost entirely of fish, but 
owing to the small number of loons usual in any one locality, their direct 
economic importance is small. 
Figure 77 
Bill outline of Common Loon; scale, $. 
7. Common Loon. loon, great northern diver. Gavia immer . L, 32. Plate II A. 
Distinctions. The summer adult Common Loon is easily separated from any of the 
other Loons, except the Yellow-billed, by its marked coloration but young birds may be 
more difficult to differentiate. From the Yellow-billed, which is Dut slightly larger, adults 
may be separated by black instead of yellow bill and green instead of purple reflections on 
the throat. Juveniles and summer adults have rather pale bills and the shape, slightly 
arched instead of straight culmen (compare Figure 77 with Figure 78), is probably the 
best distinction. As the latter occurs regularly only in the far north there is little oppor- 
tunity for confusing these two. 
From the immature of the Red-throated Loon young birds may be told by size and their 
lack of small, sharply-defined white spots on the back. From the juvenile Black-throated 
or Arctic Loon, size appears to be the only reliable criterion in immaturity or winter. 
Field Marks. All black head, throat, and bill. In juvenility or in winter plumage, 
size, and unspotted back. Most of the Loons seen on our inland waters are this species. 
Nesting. On the boggy or rocky shores close to fresh water where, when alarmed, it 
can slide directly into the water. The rather bulky nest is built of decaying vegetable matter. 
Distribution . Over the whole of Canada, breeding wherever conditions are suitable 
and the birds are not disturbed. In many cases they remain in winter as long as the water 
is open. 
Most frequenters of our waterways and lakes are familiar with the 
long, loud laugh of the Loon. The Loon has many other strange wild 
notes; among them one beginning low, rising high, and then dropping 
suddenly. It is often noisy at night or just before a storm and birds 
frequently call to and answer one another across the water. 
Owing to the constant encroachments of settlement, and the conse- 
quent disturbance of its nesting places, the Loon has been growing scarcer 
of late years, and in many of its old haunts it is now seldom seen except 
during migration. However, there are still many lonely lakes in the 
great uninhabited north where it can live and breed undisturbed, and the 
immediate loss of this picturesque species need not be anticipated. Proper 
local protection, enforced by an awakened public opinion, would undoubt- 
edly restock our lakes and ponds in summer as well as augment the number 
that make passing visits. Loons are strictly protected at all times by the 
terms of the Migratory Birds Convention Act. They may be legally killed 
nowhere in either the United States or Canada. Under the terms of this 
treaty, only where their depredations are proved to be serious can permits 
be issued for their destruction. 
The damage to game fish charged against Loons by anglers may locally 
have some foundation in fact, but is often subject to exaggeration. The 
failure of fish supplies may commonly be attributed to every possible 
cause except the most important one, viz., human over-fishing. Too 
