128 BiCKNELL on ike Singing of Bii-ds. [April 



mon. Dates of last songs fall between October 21 and November 

 I. In two years I have no record later than the 8th, but it seems 

 not unlikely that in these years transient final days of song were 

 missed. It is, however, not improbable that, if subsequent to 

 the beginning of autumn song the weather should prove unfavora- 

 ble, the second song-period may be allowed to lapse. 



Through the latter part of August many Robins may be seen 

 flying about, minus remiges and rectrices, in varying number. 

 Adults of both sexes taken in the second week of October have 

 the new plumage perfected with the exception of some of the 

 smaller feathers. 



Turdus mustelinus. Wood Thrush. 



This most admirable song-bird is in voice from its aiTival, in 

 late April or early May, until about the middle of August. But 

 towards the end of July singing becomes less universal with 

 members of the species, and soon after has come to be inconstant 

 and confined to the earlier and later hours of the da}^ Songs 

 are usually to be heard through the first week of August, and 

 sometimes for a week later (August 6-15), when singing some- 

 what abruptly ceases, seven or eight weeks before the final depart- 

 ure of the species.* 



After the cessation of singing these Thrushes become shy and 

 inactive, afiecting the most retired parts of the woods, and only 

 the careful observer will discover that they have not disappeared. 

 Even their call-notes almost have been* discontinued, and when 

 heard are so low in tone and so brief as almost to seem as if 

 accidentally uttered. Before their departure, however, though 

 they do not again sing, voice is partially regained ; and in October, 

 even so late as the middle, or rarely last of the month, their call- 

 notes may sometimes be heard uttered with the same vehemence 

 as in the spi'ing. 



The suspension of song by this bird during two months preced- 

 ing its departure can be accounted for, according to the probabili- 

 ties earlier adduced, by physiological activities antagonistic to 

 song operating during that time. In late August adults are 



*An exceptionally late date for song is August 23, 1883. On that day I for some 

 minutes listened to the singing of a Wood Thrush which was of a very unusual charac- 

 ter. Though all the notes of the normal song were given, they were so faintly uttered 

 and separated by such distinct pausesi as to make it seem probable that they resulted' 

 from the first trial of a young bird. 



