SHIRAS EXPEDITIONS TO WHITEFISH POINT. 159 



trout, common pike, and sculpins Avere found eating other fish. Of 

 these the most important destroyers seem to be the common pikes, for 

 they are numerous and often of a large size. Sculpins a])pear to eat 

 other fish extensivch' in the region, including members of their own 

 species. Some fish-eating ])irds are common. These are loons, blue- 

 herons, night herons, bitterns, kingfishers, mergansers, and grebes. 

 Kingfishers frequentl}^ attack schools of small fish. Minks are con- 

 sidered common in the region. If they are, many fish are probably 

 eaten by them. Fish probably to some extent destroy other verte- 

 l)rates for large pikes are said to catch young muskrats and young 

 ducks in the marsh lakes. 



Fish affect each other through competition for food. A conspicuous 

 instance of this in the Whitefish Point region is in the case of the hosts 

 of nine-spine sticklebacks eating the same food as the much-less num- 

 erous little whitefish and herring and other species of the shallow water. 



Most of the species of fish in the Whitefish Point region influence man 

 in unimportant ways. Whitefish, herring, and brook trout, furnish food 

 for residents and the first two are of much commercial value at White- 

 fish Point, where many tons of them are taken each year and are the 

 cause of a very important fishery there. ]\Ian and the beaver have 

 varied the character of the fish habitats through dams, channels, and 

 other structures that they have built about the marsh lakes. 



BIBLIOGRAPHY. 



Aljbott, C. C. 1875 



1875. Notes on Some fishes of the Delaware River. Report of the 

 Comm. of Fish and Fisheries, 1875-1876; 825-845. 

 Adams, A. L. 



1873. The Lake Trout. Report of the Comm. of Fish and Fisheries, 

 1872-1873; 357-362. 

 Adams, C. C. and others 



1906. An Ecological Survey in Northern ^Michigan. Report of the 



State Board of Geological Survey of Michigan for 1905. 

 1909. An Ecological Survey of Isle Royale, Lake Superior. Report 



of the State Board of Geol. Survey of ^Michigan, for 1908. 

 1913. Guide to the Study of Animal Ecology. The Macmillan Co., 

 New York. 

 Agassiz, L. 



1850. Lake Superior: its Physical Character, Vegetation and 

 Animals compared with th()s(^ of other and ,-iniilar Regions. 

 Boston. 

 Allen, A. A. 



1913. The Red-winged Blackbird. A Study of the Ecology of a 



