126 AMERICAN MIDLAND NATURALIST 



The last day I saw the species, a number of birds were bathing 

 in a lake late in the afternoon. Was this bathing preparatory for a 

 night flight? I can not say what determined the birds to leave 

 so many days ahead of their usual time for migrating. In fact 

 the more observations I make on the migration of birds, the 

 clearer it becomes to me that it is quite beyond our efforts to give 

 a satisfactory reason for the differences noted in the time of migra- 

 tion of most species. 



A species that is sure to leave in autumn within one or two 

 days of a certain date is the Baltimore Oriole. This regularity 

 is quite exceptional, for I can not find another species that shows 

 such nearness in its dates of migration. As in the cases of disparity 

 in the dates of migration so in this instance of regularity, I can not 

 say what was the determining cause of the birds' movements. 



A number of species were recorded but once in certain months, 

 this date being selected as the one before the day of migrating. 

 Such records were made of the Redstart, Crested Flycatcher and 

 Vesper Sparrow in September; House Wren, Flicker, vSapsucker, 

 Yellow Palm Warbler, Hermit Thrush, Sparrow Hawk, Greater 

 Yellowlegs and Red-breasted Nuthatch in October; Bluebird, 

 Purple Grackle, Cardinal, Canada Goose and Hairy Woodpecker 

 in November; Northern Shrike in December. The fact that these 

 species were seen but once would seem to indicate that the indi- 

 viduals were migrating birds. There is some probability that on 

 certain days the writer may have missed a number of these spec es, 

 and thus failed to obtain the true dates of their migration. 



The writer wishes to call attention to the only record he made 

 of the Hermit Thrush this autumn — October 13. In two previous 

 years, this species appeared late in August, making the date of 

 arrival this year 44 days later than the earliest arrival on August 

 29, 1 910. Who can furnish a clue to this case of remarkable dis- 

 parity in dates of migration? 



August. 



