^°'' igui^"^] Tyler, Call-notes of Migrating Birds. 137 



able to watch the Thrushes drop from the sky into a small wood 

 where he could afterward examine the birds at short range. He 

 secured five specimens. x\lthough I have gone out-of-doors in 

 the morning twilight repeatedly in August on days when I have 

 heard the whistles in great numbers before dajdight, I have never 

 seen the birds (Veeries at this date) ; as soon as it has grown light 

 enough to make out a bird in the air, the calls have stopped and 

 no more birds have flown over. 



The Thrush calls heard during October, generally in the latter 

 part of the month, are very similar to the Veery whistle. This 

 third Thrush whistle is heard very irregularly, — on most nights 

 none at all, but on a few nights in very great numbers. At this 

 season of long evenings, it is not uncommon for the birds to start 

 on their night flight as early as six o'clock. In tone of voice this 

 note, a soft nasal whistle, resembles the Bluebird's call. It has, 

 however, but one syllable and is inflected downward in pitch very 

 slightly, — often not at all. The letters "Per" or "Ter" suggest 

 the call. On October 29, 1913, I saw a company of half a dozen 

 Hermit Thrushes repeat this note frequently as the birds flitted 

 about in a gray birch wood. When they uttered the note they did 

 not open the beak (at least at short range I could not see them do 

 so), but at each repetition the feathers of the throat were slightly 

 raised. During the previous night there had been a considerable 

 flight of Hermit Thrushes and just before sunrise (a misty morning 

 with a light S.E. breeze) I had heard numerous Thrush calls from 

 birds passing overhead. 



These three whistles heard respectively (roughly speaking) in 

 August, September, and October account satisfactorily, I think, 

 for the Veery, Swainson's, and the Hermit Thrush. The two other 

 Hylocichlse, the Gray-cheeked and Bicknell's, are of comparative 

 rarity in Eastern Massachusetts and their periods of migration 

 here coincide practically with the passage of the Olive-back. It is 

 very probable therefore that I have not distinguished the calls of 

 these rarer Thrushes because their voices vary little from the calls 

 of the abundant Olive-back. 



During the month from mid September to mid October there are 

 more nocturnal bird-notes to be heard than any other time. The 

 majority of these calls to my ear are identical to the common 



