282 Field Museum of Natural History — Zoology, Vol. IX. 



Family GAVTID^. Loons. 



The Loons are a small family, consisting of one genus and five 

 species, three of which occur on Lake Michigan. They feed prin- 

 cipally upon fish and are expert divers and swimmers, rarely leaving 

 water, except during the nesting season. 



Summer 



Loons. 



Winter. 



Genus GAVIA Forster. 



7. Gavia immer (Brunn.). 

 Loon. 



Urinator imber (Gunn.), A. O. U. Check List, 1895, p. 3. 



Distr.: Ranges throughout the northern part of the northern 

 hemisphere, breeding from the northern United States northward; 

 south in winter to the Gulf of Mexico and Lower California. 



Adult in summer: Head and neck, black, showing green in some 

 lights; a patch of white, streaked with black, on the throat and sides 

 of the neck; under parts, white; back, streaked and spotted with white. 



Adult in winter, and immature: Head, grayish; throat, white or 



