104 MICHIGAN SURVEY, 1908. 



They were preying principally on the sparrows, and were creating 

 great havoc among them. Coming with the great wave they remained 

 throughout the day and passed on with it that night, only one being 

 seen the next morning. 



The migration of the hawks is thus seen to have been intimately con- 

 nected with the migi'atiou of the smaller birds upon which they preyed, 

 and seems to give at least one instance of bird migration being in- 

 fluenced by the food supply. 



During cold, rainy mornings the hawks rai'ely appeared in the open, 

 usually not until about 9 o'clock. This, however, was the time the 

 warblers appeared on such days, and this may also have determined 

 their appearance. 



d. Owls. Only two species, the Great Horned and Acadian Owls, 

 were seen. These were residents at this time and only concerned mig- 

 ration in that they sometimes preyed upon the migrants. Their effect 

 was probably slight. 



e. Thrushes. Six species were observed migrating, the Bluebird, 

 Robin, Wilson's, Olive-backed, Gray-cheeked and Hermit Thrushes. A. 

 pair of Blue Birds nested in a dead Birch at Wendigo, and this family 

 left the island about August 22. On the 24th a small flock probably 

 consisting of two families appeared at the first clearing and remained 

 about the tangled brush until August 31, when they also left. No others 

 were seen except on September 11 and 12. Robins were seen twice 

 during August, but on Septemljer 6, the first real migratory move- 

 ment was initiated, and from then on the number rapidly increased. 

 Small flocks numbering a dozen or so wandered about the clearings 

 and open woodland. ]Mauy disappeared on the night of September 12, 

 but the number was soon replenished, and at the time the observations 

 were closed the Robins were quite abundant. 



The most commgn of the Thrushes was the AVilson's. They bred on 

 the island and showed no indications of the migrating spirit until the 

 latter part of August, when they gradually increased in numbers and 

 moved about to a greater extent. After September 6 they became 

 rather scarce, and none were seen after the 14th. Their place was 

 taken by the Olive-backed, and later the Gray-cheeked became abundant. 

 Many immature Olive-backed were seen but this species had nearly 

 disappeared when the great flocks of Gray-cheeked arrived on September 

 12. They showed little fear and did not seem to be frightened at the 

 report of a gun. The flocks of the Gray-cheeked were made up of 

 immature and adult birds, all in perfect fall plumage. 



f. Other Birds. Following the breeding season the woodpeckers wan- 

 der about the island making what might be called a local migration. 

 Perhaps some of these birds leave the island in the fall and probably 

 others come in from the north. In one instance, that of the Flicker, 

 their numbers are enormously increased during the latter part of 

 August and all through September. It is very improbable that any of 

 these latter birds winter on the island. Flickers were seen evei'y day, 

 but the number greatly increased toward the last of September, and 

 from the report of residents the number continues to increase until late 

 October when they appear to leave the island. Many were found dead 

 without any apparent cause, and it was reported that in the latter 



