ECOLOGY OF ISLE KOYALE. 107 



wind blowing about 4 miles per hour. The Palm Warblers continued to 

 come in large flocks and were by far the most abundant bird at the 

 Harbor. The vanguard of the migrating host of Savannah Sparrows 

 appeared early on the morning of the 31st, and by evening the clearing 

 was fairly covered with them; more came during that night and all 

 the next day large flocks were arriving at the first clearing. There was 

 no appreciable increase during the four succeeding days among the bird 

 migrants. The third day of the wave (September 1) the barometer stood 

 30.1 inches, temperature 52°, with a northeast wind and a cloudy sky. 

 This day marked the close of this wave both of birds coming to and 

 leaving the island. This wave might have been checked either by the 

 gales which followed or the change of the wind from north to northeast. 

 A few birds attempted to cross during these succeeding days, as many 

 were killed by striking the lighted windows, etc., or were found in an 

 exhausted condition. These were probably part of that steady stream of 

 migi'ants which continues to pass south during the fall, without any 

 marked wave and in general disregard of the weather conditions. 



o. Third Wave. This wave was noticed first on September 5 when the 

 bulk of the Chipping, White-throated, and Savannah Sparrows left the 

 island, and on September 6 the first real migration of the Robin com- 

 menced. I have considered these two days as parts of one wave, con- 

 trolled by the same conditions, for probably the same influences acting 

 at the same time caused the sparrows to leave the island and the Robins 

 to leave their more northern home. The Meather conditions were such 

 as seem to be most favorable for fall migration. On September 5 the 

 high pressure had advanced to an area lying from Winnipeg on the north 

 to Memphis on the south, and extending east nearly to Duluth. The 

 barometer stood at 30.1 (high) with a northwest wind blowing six 

 miles per hour and a temperature of 39°. The day was partially cloudy, 

 but no rain fell. On the 6tli an area of high pressure had formed over 

 the region directly to the north and northeast of the island. A moderate 

 northwest wind prevailed with the barometer at 30.1 inches, and ther- 

 mometer 42°, and the weather was clear. A few Robins had been noted 

 before this, but these were only scattered individuals or pairs, but on 

 this date a large number came to the island, both young and adults being 

 seen, although the latter greatly predominated. 



4. Fourth Wave. On September 12 the largest wave of the season 

 occurred. For number of species as well as individuals it could scarcely 

 be compared to the other large waves, a total of 41 species being ob- 

 served in actual migration on this day. On the previous day the low 

 area was central over Lake Erie, and a similar area was formed over 

 the Dakotas. The barometer stood at 29.8 inches, the temperature at 

 52°, with a north wind and a clear sky. It was cloudy, however, on the 

 north shore. On the morning of the 12th the low area was central over 

 New England, while the western one had moved south and had been 

 followed by an area of high pressure central over the Dakotas and 

 Western Minnesota. The island lay between the isobars of 30.1 and 30.2 

 inches, with a temperature of 42°, and a northwest wind averaging 8 

 miles per hour. The day was clear and seemed perfect in every way. 

 'The birds were so plentiful in the clearing at 6:30 A. M., as to attract 

 ipiy attention from the windows. Unlike the other bird waves, the 



