40 MICHIGAN BIRD LIFE. 
Fig. 2. Nest and Eggs of Pied-billed Grebe. 
From photograph by Thos. L. Hankinson. 
Family 2. GAVIIDAt.—Loons. 
KEY TO SPECIES. 
A. Tarsus shorter than middle toe without claw.—B, BB. 
B. Depth of bill at base .90 inch or more.—Common Loon. No. 4. 
BB. Depth of bill at base .80 inch or less.—Black-throated Loon. (Ap- 
pendix.) 
AA. Tarsus longer than middle toe with claw.—Red-throated Loon. No. 5. 
4. Loon. Gavia immer (Brunn). (7) 
Synonyms: Great Northern Diver, Walloon, Ring-necked Loon, Black-billed Loon, 
Guinea Duck, Greenhead.—Colymbus immer, Briinnich, 1764.—Colymbus imber, Gunn., 
1761.—Urinator imber, Stejn., 1885.—Colymbus torquatus and Colymbus glacialis of 
most of the older writers. 
Figure 4. 
Readily recognized by its large size, and, in summer, by its green head, 
checkered black and white back, and white under parts. Largest of our 
divers. 
Distribution.—Northern part of Northern Hemisphere. In North 
America breeds from the northern tier of states northward; ranges in 
winter south to the Gulf of Mexico and lower California. 
In Michigan most abundant during migration, but generally distributed, 
so that there is hardly a stream or pond on which Loons are not seen each 
season. Formerly it nested abundantly on most of the ponds and lakes 
of the state, even to the southernmost border, but of late years it is much 
