Gulls. 



47. Great Black-backed Gull (Larus marinus). L. 

 29. Ads. , summer. Back and wings slaty black; wing 

 feathers tipped with white. Ads. , winter. Similar, but 

 head and neck streaked with dusky. Yng. Back 

 grayish brown margined with buffy white; rump whiter; 

 primaries black; below white more or less marked with 

 dusky. Notes. "A braying ha-ha-ha, adeepkeow, keow, 

 a short barking note, and a long-drawn groan, very 

 loud and decidedly impressive." (Brewster.) 



Range. — North Atlantic and northern Europe; breeds In North 

 America from Nova Scotia to Greenland; winters south to Great 

 Lakes and South Carolina. 



48. Slaty-backed Gull (Larus schistisagus). L. 26. 

 Ads. , summer. General appearance of No. 47; back 

 lighter; primaries as figured. Ads. , winter. Head and 

 neck streaked. Yng. Above brown margined with 

 buff and white; primaries brown; tail brown with little 

 or no mottling; below brown. 



Range. — "North Pacific, chiefly on the Asiatic side; Herald Island. 

 Arctic Ocean, and Alaskan coast of Bering Sea." (A. O. U.) 



49. Western Gull {Larus occidentalis). L. 24. Ads. , 

 summer. Head, neck, tail, and underparts white; back 

 slaty gray; outer primaries black, a large white spot 

 near tip of first one. Ads., winter. Crown and hind 

 neck streaked with brownish. Yng. Grayish brown 

 mixed with white; wings and tail fuscous. Notes. 

 Ooeek, ooeek, ooeek; ca-ca-ca, and other calls. 



Range. — Pacific coast; breeds and winters from Lower California to 

 British Columbia. 



57. Heermann Gull {Larus heermaui). L. 17. Ads., 

 summer. Bill red;head and throat white, shading into slate 

 above and below; -tail blackish, tipped with white; 

 primaries black. Ads., winter. Head and neck streak- 

 ed with grayish brown. Yng. Uniform grayish 

 brown. 



Range. — Pacific coast of North America; breeds from Mazatlan, 

 Mexico, north to Lower California; occurs regularly north to Van- 

 couver Island; winters south to Panama. 



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