AMERICAN WAKBLF.US. 75 



Song. The earliest date that I have heard the Blue Yel- 

 low-backs sing is March 29. This was at Nassau in 1884. 

 They sing while migrating through Florida and northward; 

 thus they were in full song at Barnstable when I arrived there 

 the last week in June of this year, and they continued to sing 

 generally as late as July 15, after which date most of them be- 

 came silent, but I heard a single one give the full song on the 

 eighteenth of the month. 



The song is somewhat variable, but is always unmistaka- 

 ble, as it is peculiar in intonation as well as in method of deliv- 

 ery. The full song begins with three or four lisping or wheezy 

 notes, and ends with a sharp, almost lash-like note. The en- 

 tire song may be rendered by the syllables, " Svjee sivee swee 

 swee swee-zer''\ This entire song is not always given, for 

 often the two last notes are omitted, I noticed no difference 

 in the song from the first of the season to the last, and was 

 quite surprised to find that the birds had ceased singing with- 

 out any preliminary shortening or other change in their lay. 



Migration and Breeding Range. As separated from 

 the southern form by Mr. Brewster in 1896, the Northern Blue 

 Yellow-back is restricted to New England, New York, and 

 the northern tier of states, and northward into Ontario, Nova 

 Scotia, and New Brunswick. Through this range, however, 

 it actually breeds only where the usnea lichen occurs in sufific- 

 ient abundance to form long tufts on the trees. It thus oc- 

 curs commonly on Cape Cod, in Maine and in places in other 

 northern sections mentioned, and locally elsewhere, for where- 

 ever the lichen appears, even if it be confined to a single tree, 

 these warblers will usually find it and nest in it, A single red 

 cedar which stands near Hurd's Pond in Wayland, Massachus- 

 etts, was, some years ago, plentifully overgrown with the us- 

 nea lichen, and as long as this remained on the tree in any 

 quantity the Blue Yellow-backs nested in it. Unfortunately 

 my notes made before the separation of the sub-species do not 



