538 BULLETIN 2 03, UNITED STATES NATIONAL MUSEUM 



(1938) have this to say about the prenuptial molt: "In February and 

 March there is a body molt, apparently much more extensive in the 

 young than in adults. The former at this time take on the bluish head 

 and chest of maturity. There is some individual variation, but in 

 general it may be said that the extreme richness of coloration is not 

 attained until the second year. The spring plumage of older birds is 

 the result of a limited renewal plus the wearing away of the paler 

 colored tips of the fall plumage. It takes place in February and March 

 at the same time as that of the younger birds." 



Food. — Mrs. Bailey (1928) lists in the food of this warbler "insects, 

 including the click beetle, dung beetle, flea beetle, caterpillars, and the 

 alfalfa weevil." No comprehensive study of its food seems to have 

 been made. 



Behavior. — MacGillivray's is the same timid, shy, and elusive little 

 bird as its eastern counterpart, the mourning warbler. Gabrielson and 

 Jewett (1940) write: "The birds are much in evidence in their chosen 

 haunts in late April and early May while the courtship is in progress, 

 but when household cares occupy the daylight hours they become as 

 elusive as field mice, slipping about through the thickets like shadows, 

 only the sharp alarm note betraying their presence to an intruder." 



Voice. — Rathbun says in his notes : "Its song begins with three or 

 four quickly given notes on nearly the same key, followed by several on 

 a lower key, but this may be varied at times. It is a quite distinctive 

 song and when once learned is not easily forgotten. Throughout there 

 seems to be a minor key ; the song lacks smoothness and when heard at 

 a distance has somewhat of a roughness ; but, like so many of the songs 

 of birds, it is heard at its best when one is close to the singer. Should 

 its chosen territory be infringed upon, the intruder becomes aware of 

 its presence by hearing a rapid, harsh alarm note, which may be 

 repeated many times." Du Bois tells me that the song of MacGilliv- 

 ray's warbler "resembles the syllables te-te-te-te-cheweet-cheweet- 

 cheweet., the first part being about a note higher than the latter part. 

 It is uttered rapidly, the whole song requiring about a second and a 

 half. Sometimes there are only three ^e's, followed by four cheweefs.^'' 



Mrs. Amelia S. Allen writes to me : "The song of the Tolmie warbler 

 is more musical than most warbler songs. The first half of the song is 

 composed of double notes with a rising inflection ; the second half with 

 a falling inflection : Swee-eet^ swee-eet^ swee-eet^ peachy^ peachy^ 

 peachy. But I hear also : Peachy^ peachy, peachy, twit twit twit, the 

 first half with a falling inflection." Grinnell and Storer ( 1924) write : 



At Hazel Green, on May 14, 1919, a bird was observed fully 50 feet above the 

 ground on one of the lower branches of a large incense cedar. * * * This bird 

 sang ten times in two minutes, changing position usually after singing twice on 

 one perch. The song was rendered by the observer sizik, sizik, sizik, lipik, lipik, 



