180 YEARBOOK. PUBLIC MUSEUM, MILWAUKEE [Vol. III. 



the Milwaukee Zoological Garden, where it is now being held and is 

 proving of much public interest. 



The bird was first observed by Mr. Frank McKone, on the Mil- 

 waukee River, February 10th, 1925. On the following day the speci- 

 men was easily taken by one of the employees of the Garden. 



While thousands of the common gulls swarm the rivers and lake front, 

 finding food everywhere, this extraordinary individual seemed an outcast. 

 It was so starved that it was nearly exhausted. Patches of plumage 

 were badly disarranged and mutilated, probably caused by the hector- 

 ing of other birds. It has been frequently observed that individuals 

 of a peculiar color phase, when found among those of the common 

 plumage, are mistreated. They are, as popularly termed, "black 

 sheep." 



Detailed information from the files of the Biological Survey indi- 

 cates that most of the Herring gulls seen as winter residents about Mil- 

 waukee, migrate from summer nesting grounds on Sister Island, Gull 

 Island, and Sand Island in the northern Great Lakes. It may, there- 

 fore, be fairly assumed that this bird also had its origin in that locality. 

 According to local records, black gulls have never been seen here. 



The occurrence of unusual color phases among all animals is only 

 occasional. The extremes are, albinism and pure melanism, with 

 many individuals showing partial tendencies to either. Partial ten- 

 dencies are observed in the second generation of the mating of the 

 color phase with the original type. Melanism is more frequently seen 

 in carnivores and rodents, while albinism is more common in native 

 birds than is melanism. This gull, being of the latter phase, is of 

 great interest and value. 



The adult Herring gull, of the usual coloration, during the winter 

 season is all white with the exception of the bluish grey back and 

 rump feathers, and the large black-tipped primaries. The mandible 

 is yellow and the legs are a yellowish flesh color. However, in addition 

 to the unusual coloration of this bird's plumage, its feet and legs are a 

 dull black. The bill, as shown in figure 98, is marked similarly to 

 that of the immature bird in normal plumage, but is much darker in 

 general color. The iris is j^ellow. 



In the common phase the grey and white coloring is due to the 

 structure of the feather, while in this melanistic form the coloration is 

 due to pigmentation. 



Although this specimen is at first sight apparently a pure melanistic 

 form, a scrutiny of the entire plumage reveals that this is not the case. 

 The tips of the contour feathers are a positive black, which, about 



