18 MICHIGAN SURVEY, 1905. 



collecting birds. Mr. McCreary devoted his time to the study of the habitats 

 of the birds and to the collecting of ants, and Mr. Maclean to collecting 

 vertebrates alone. The invertebrates and cold blooded vertebrates were 

 collected by the writer, with the assistance of the other members of tjie 

 party. 



Except in the case of the molluscs and birds, no attempt was made to 

 make exhaustive lists of the different groups, owing to the lack of time. 

 The collections include principally the representative forms in the different 

 habitats, as is indicated in the description of the stations and in the annotated 

 lists. 



While running the line of survey and establishing the stations, the de- 

 pendence of the biota on the environmental conditions, and the adjustment 

 between these conditions and the plant and animal societies was given 

 special attention. Much light was thrown on the interpretation of these 

 interrelations by considering the physiography in its dynamic or unstable 

 aspect. The physiography is the resultant .of the geological formations 

 and the agencies constantly at work modifying them. Since the biota is 

 dependent on the physical conditions in the different habitats, it is also un- 

 stable. A knowledge of the present and past conditions, which can only 

 be obtained through a knowledge of the processes involved, is therefore 

 necessary to explain the origin and distribution of the life of this region. 



Both of the localities worked are favorable for study from the ecological 

 standpoint, for the primitive and natural order of life prevails practically 

 free from the disturbing influences of man. The forests have not been 

 lumbered, and, although mining has been done both in the Porcupines 

 and on Isle Royale, the workings were all early abandoned, and the con- 

 ditions of nature have reverted so nearly to their primitive order that the 

 only evidences now remaining are caved-in shafts, and occasional growths 

 of aspen and birch which mark the site of old clearings. The whole region 

 is wilderness and practically uninhabited. For this reason, field head- 

 quarters were established in order to have a suitable place where provisions 

 could be stored, and where the specimens could be properly cared for. Owing 

 to the nature of the woods, travel was arduous and all extended trips had 

 to be made with packs, making it difficult to care for specimens more than 

 two days' journey from camp. This difficulty, in the Porcupine Mountains, 

 was counterbalanced by the rough nature of the topography that made it 

 possible to get a large variety of habitats within a comparatively small area. 

 The territory covered by the survey was, therefore, limited to about twelve 

 square miles, in order that representative habitats might be worked in 

 some detail. On Isle Royale, the low relief made it necessary to extend 

 the line much farther in order to get a variety of habitats. It was, for this 

 reason, impossible to cover the ground in as much detail. 



It is well at this time to acknowledge our indebtedness to Mr. David 

 Allie, caretaker of the Carp Lake Mining Property in the Porcupine Moun- 

 tains, who placed at our disposal a large double shack furnished with bunks, 

 stove and dishes, and aided us in many other ways. We are also indebted 

 to Mr. Charles Preulx and Michael Hollinger, caretakers of the grounds 

 of the Washington Club, Isle Royale, who also assisted us in many ways- 



