20 PROCEEDINGS OF THE 



sional presence of aberrant notes, which add greatly to the diffi- 

 culty of deciding exactly what the bird is doing and may have 

 confused many reliable students. These perplexing notes may 

 be divided into two classes: those which interrupt the regular 

 couplets and those which do not, the latter being mere orna- 

 ments to the couplets, which are sounded at the same time. 

 Rec. 8 is a good example of the first class. Here the aberrant 

 triplets (sets of three notes barred with two lines) break up the 

 couplets ('Ueacher" notes) which cease while the triplets are 

 being sung. The latter differ in tone-quality and are pitched 

 about an octave higher than the couplets. Probably the trip- 

 lets are plagiarized from the flight-song, for the combined effect 

 is similar to that of the flight-music and approaches, I doubt 

 not, the aberrant utterances mentioned by Mr. Thayer.^ Un- 

 like Mr. Thayer's song, this was probably not a prelude to the 

 flight-song, for it was rendered from a tree in the middle of the 

 day and continued for three-quarters of an hour, after which 

 the bird dropped to the ground. 



The second class of aberrant notes is more extraordinary and 

 has not been mentioned, so far as I am aware, in the literature 

 of the Oven-bird. I have caught it on several occasions, both 

 in Maine and New Jersey, and in not one case was it a prelude to 

 a flight-song. Sometimes it was a trill (Rec. 6), sometimes the 

 repetition of a single note (Rec. 9, p. 21) and sometimes an 

 extra series of high couplets (Rec. 7), but in most cases the 

 regular couplets are continued to the end.'* When I first de- 

 tected this supplementary series of notes, I did not ascribe it to 

 the Oven-bird above my head, but to some unknown warbler 

 farther away, because it was rendered an octave higher than the 

 main part of the song and with an entirely different tone- 

 C|uality. On this occasion it was a rapid trill, like a Pine 

 Warbler's song, for which my companion mistook it, but de- 

 livered with the tone-quality of a violin string. Though it 

 generally entered about the middle of the song, it often did so 

 at any point from the beginning to the end, and occasionally it 



'Quoted in "Warblers of N. America," p. 223. 



* Kec. 7 is an exception, in which one aberrant triplet breaks the couplets 

 at the end. 



