46 KoPMAN, Bird Migration in the Lower Miss. Valley. \_]m 



the evening had made the conditions excellent for migration. 

 The tremulous whistle was caught up as frequently as the notes 

 of Yellow Warblers, Indigo Buntings, Sandpipers, Green Herons, 

 and Night Herons. More than nine years later, May 9, 1903, I 

 settled the mystery that had perplexed me more than any ques- 

 tion that had come up in my experience. I caught one of the 

 birds making the same note in the day-time. It was a Wilson's 

 Thrush. Of all the guesses I had made, I had been unsuspi- 

 cious of the thrushes. The abundance of the birds heard in 

 night migration had led me off the track. As a bird of the 

 woodland, the Wilson's Thrush is so retiring, and therefore seen 

 so infrequently that one would scarcely hit upon it as the inces- 

 santly heard migrant. Once I had heard the note, however, I won- 

 dered that I had not before recognized the famous whew or whoit 

 by which John Burroughs characterizes the voice of the Veery. 

 It was dumbfounding to think that while in all my ornithological 

 observations in this section I had never seen a score of Veeries 

 in the course of ten springs, I had heard countless hundreds. 

 Since the spring of 1897 I had known that both the Gray-cheeked 

 and Olive-backed, especially the former, might appear in astonish- 

 ing numbers as transients in late April and the first week of May. 

 In hedges, weedy places, and willow thickets in pastures and 

 other open places, I had seen scores of Gray-cheeked Thrushes in 

 a single day the early part of May, but the Wilson's Thrush had 

 been a consistent rarity. For the latter part of spring, in this sec- 

 tion, it may be stated as a general proposition that these three 

 transient thrushes will be found migrating together. I have cotne 

 across heavy waves of the Gray-cheeked and the Olive-backed on 

 various occasions the latter part of April and the early part of 

 May. Usually at the same times the note of the Veery may be 

 heard in night migration. The past spring I observed both the 

 Gray-cheeked and the Wilson's together in a thicket of willows 

 and hackberries between the new and the old levee at Audubon 

 Park, New Orleans. The birds were detained by a slight tempo- 

 rary fall in the temperature that first became apparent May 9. 

 I spent half a morning watching just these thrushes, and it was 

 after watching for some time that I first heard the note of the 

 Wilson's. The first day I could not see any of the Wilson's 



