424 BULLETIN 2 3, UNITED STATES NATIONAL MUSEUM 



season tliey may begin singing as mucli as 40 minutes before sunrise, 

 and they may sing until sunset. They will sing in spite of tempera- 

 tures as low as 25° F., and even a pouring rain may not stop them. 

 They sing wherever they are — in the trees, on the wing during a flight 

 from one tree to another (though their mouths may be full of insects 

 they are taking to the young) , on the ground (though this is rare) , and 

 even on a perch within a foot of their nest and young. When singing 

 most steadily, they commonly repeat the song about seven times a 

 minute. Early in the morning I have counted, during such singing, 

 237 to 250 songs per hour. 



None of the various syllabifications that have been used to describe 

 the song is very satisfactory. Perhaps this is not remarkable, for (as 

 shown by the sound-film record made by the Cornell party) there 

 may be more than 100 up or down slurs in one second, and pitch 

 changes of several tones in less than one-hundredth of a second. Ax- 

 tell (1938) very rightly compared the song with that of the northern 

 waterthrush {Seiurus novebo7'acensis) and the house wren {Troglo- 

 dytes aedon), saying that they "are the most likely sources of con- 

 fusion" in the identification of Kirtland's warblers by song. "The 

 Water-thrush's song starts high and descends; the Kirtland's starts 

 low, goes higher, and may end either high or low. As compared with 

 the wren, the warbler's song is shorter, of fewer notes, and has a more 

 definite beginning and ending." "The loudness of the song is one of its 

 most outstanding characteristics. In the bird's desolate jack-pine 

 haunts it may be heard from a quarter to a half mile. Its liquid, bub- 

 bling quality, and its lively, emphatic manner of delivery seem to be 

 invariable features." Axtell adds that the Kirtland has the lowest- 

 pitched song of any of the eastern Dendroicas. 



I have sometimes noticed a Kirtland change his style of song, but 

 only rarely after the early part of the season. Most individuals have 

 quite characteristic songs, and after spending a few days in a given 

 area of the nesting range, one can recognize by his song the owner 

 of every territory within earshot. 



A strange characteristic of Kirtland's warbler is its habit of singing 

 incomplete songs. Occasionally a song will be broken off abruptly at 

 any point and for no apparent reason. Sometimes an incomplete song 

 is followed almost immediately by a complete one. 



Rarely I have found a male that has an extremely aberrant song — 

 quite unrecognizable as that of a Kirtland. Two males that I noted 

 in Oscoda County (June 16, 1941, and June 6, 1944) had songs that 

 were harsh, completely unmusical "rattles," reminding me somewhat 

 of a cowbird. Another male (noted June 1, 1945) gave a simple trill 

 very like that of the field sparrow {Spizella pusilla) except that it 



