52 MICHIGAN BIRD LIFE. 



TECHNICAL DESCRIPTION. 



One of the largest gulls found within our limits. The tail always even, that is, neither 

 rounded nor forked, the head always white in the summer adult. Primaries pale pearl- 

 gray, becoming pure white at tip. Mantle pale pearl-gray. Some specimens are pure 

 white all over. In winter the adult is very similar, but the head and back of neck are 

 marked with more or less light brownish. Immature birds as large as the adults 

 never have the pure white plumage, but are more or less mottled with reddish-brown, 

 sometimes almost uniformly dark brown below, and the mantle also dark brown. The 

 bird can usually be told in any plumage by its size and the absence of any clear black in 

 any part of the plumage. 



Length, 20 to 32 inches; wing, 16.75 to 18.75; tail, 7.40 to 8.50; culmen, 2.30 to 2.70. 



12. Iceland GuU. Larus leucopterus Faber. (43) 



Synonyms: White-winged Gull. — Larus leucopterus of most authors. 



Not distinguishable from the preceding species except by careful measure- 

 ment. 



Distribution. — Arctic regions, south in winter to Massachusetts and the 

 Great Lakes, occasionally much farther south. 



This bird is precisely like the Glaucous Gull in plumage, habits, and dis- 

 tribution, differing only in size, the present species averaging decidedly 

 smaller than the Glaucous Gull. Its nesting habits and eggs are also 

 similar, except that the eggs are smaller, averaging 2.79 by 1.89 inches. 

 The impression seems to prevail that this bird is less rare than the Glaucous 

 Gull on the Great Lakes, and several authorities state this as a fact. Kum- 

 lien and Hollister (Birds of Wisconsin, 1903) call it a regular winter visitant 

 on Lake Michigan, but by no means common, although occurring more 

 frequently than the Glaucous. Nelson (Bull. N. O. C. Vol. I, p. 41) says 

 "A regular winter visitant on Lake Michigan." Dr. Brayton also says 

 it is a "not uncommon winter resident on Lake Michigan." The only 

 absolute record which we have is that of a specimen collected at Sault Ste. 

 Marie, Mich, in 1901, by Mr. John Graham, and now in the High School 

 collection at that place. A photograph and measurements furnished by 

 Mr. W. P. Melville confirm this identification. 



TECHNICAL DESCRIPTION. 



Almost exactly like the Glaucous Gull in everything but size; the bill, however, is not 

 as heavy, and particularly not as deep. Its average depth at the deepest part being only 

 about .02 of an inch, while tliat of the Glaucous Gull at the same point is from .80 to 1.00 

 inch. Length, 24 to 26 inches; wing, 14.75 to 16.50; tail, 6.00 to 0.70; culmen, 1.60 to 1.70. 



13. Black-backed Gull. Larus marinus Lirm. (47) 



Synonyms: Great Black-backed Gull, Saddle-back, Coffin-carrier. — Larus marinus of 

 most authors. — Larus maximus, Leach. 



Largest of our gulls, or at least one of the two largest, the adult always 

 recognizable by the black back which gives it the name; the immature 

 bird, however, may be confounded easily with the young of the other species 

 and can be identified only by the expert. 



Distribution. — The coasts of the North Atlantic; south in winter to 

 Long Island and Italy. 



A rare bird in Michigan waters, but undoubtedly occurs once in a while, 

 although captures must be very rare. "One was shot on the Detroit River 

 in March, 1904, and mounted by C. Campion of Detroit" (B. H. Swales, 

 MS. List of Birds of S. E. Michigan, 1904). Specimens have been recorded 

 from Wisconsin, Illinois and Indiana; and it has been reported in Michigan 



