ECOLOGY OF ISLE ROYALE. 115 



less bodies of birds thrown up by the waves. During the fall of 190."), 

 birds were several times reported as lighting- on the ships coming injo 

 the island, aud the fishermen secured several which lit on their small 

 boats after a stormi, when about two miles from land. They reported 

 the birds as very tame and allowing themselves to be handled freely. 

 The birds secured were several small sparrows, Tennessee and Palm 

 Warblers, a Saw-whet Owl, and one adult Robin. These birds were 

 all encountered near the southwestern end of the island. They had 

 probably been blown out of their course and were striving to reacli 

 the nearest point of land, as no birds would be coming from the south 

 at this time of year nor would any so completely exhausted have at- 

 tempted to leave the island. 



2. Natural Enemies. Without doubt the greatest natural enemies 

 of the birds during migration were the Sharp-shinned and Sparrow 

 Hawks. At times the Pigeon Hawk made great havoc among the 

 smaller birds, and the Owls also played a small j>art. Probably weasels 

 and minks fed to some extent on the migrants, which they caught while 

 the birds were resting. These animals, however, only destroyed com- 

 paratively few, as remains of their victims were seldom found. Like- 

 wise the Owls probably destroyed only those which came directly in 

 their path, the abundance of tlie Varying Hare furnishing a food much 

 easier tO' procure. This undoubtedly saved a large number of migrants. 

 Of the other animals, the Lynx also fed largely on the Hares and so 

 probably molested the birds very little, whiTe the family of house cats 

 kept at the club-house were more than supplied by the number of small 

 birds which met death striking against the windows, etc. 



The early migrants were preyed upon very little by the hawks, prin- 

 cipally because the Sharp-shinned Hawk had not arrived in any ap- 

 preciable numbers, and secondly, the gi'eat swarms of grasshoppers fur- 

 nished an abundance of appetizing food. As the season advanced and 

 both species of hawks grew more numerous, their effect on the bird 

 life increased. None of the smaller birds were safe, away from the 

 protecting boughs of the conifers and alders, and therefore were con- 

 fined almost exclusively to the edge of the clearings. The Sparrow 

 Hawks fed both on gi'asshoppers and on warblers and sparrows, while 

 the Sharp-shinned fed almost entirely on the latter. During the bird 

 waves the hawks became more numerous, this being esjiecially true for 

 the gre^t wave of September 12. On this date great numters of both 

 Sharp-shinned and Sparrow Hawks made their appearance, as well as 

 many of the Pigeon and a few Cooper's and Broad-winged Hawks. 

 The Pigeon Hawks in particular timed tbeir migration to that of their 

 victims, appearing and disappearing with each successive wave, very 

 few remaining on the island. The majority of the Sharp-shinned also 

 kept pace with the retreating birds and by the time the bulk of the 

 warblers and sparrows had passed they too had gone on. Among the 

 birds which suffered most heavily may be mentioned the Tennessee, 

 Blackpoll, and Palm Warblers, the Wilson's, Olive-backed, and Gray- 

 cheeked Thrushes, and the Chipping and Savannah Sparrows. Great 

 daring was shown by the Sharp-shinned Hawks. Sometimes so eager 

 were they in pursuit of their prey that they would dart within a few 

 inches of one's head. 



