4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



consist of two kinds of slightly different notes uttered in more or 

 less regular alternation. In all types of Dawn Calling the length of 

 the series of notes seems to be "indeterminate," i.e. not fixed, varying 

 within very wide limits according to circumstances. 



Melodious (and usually rather soft) "Kioo" or "Klioo" Notes are 

 the most distinctive and easily recognized of the notes uttered by 

 male yellow-rumped tanagers during typical Dawn Calling. In these 

 circumstances they may be repeated by themselves alone or (more 

 frequently) uttered in alternation with "Hoarse Flourishes" (see 

 below). They are very similar in sound to, and presumably strictly 

 homologous with, the typical Dawn Calling Notes of crimson-backed 

 tanagers. They seem to be produced by thwarting of some sexual 

 tendency, when overt expression of the tendency by sexual move- 

 ments is frustrated by the absence of a suitable "object" or partner. 

 They are apparently never closely associated with overt hostility. They 

 are uttered only by males which have become temporarily separated 

 from, or have lost, their mates. Series of such notes seem to be 

 uttered only during the first few minutes of daylight, when almost 

 all sexual activities are most vigorous, and seem to be confined to the 

 height of the breeding season, i.e. the phase of the breeding cycle 

 in which copulations are most frequent. This would suggest that 

 they are very high intensity patterns. The sexual tendencies involved 

 may be pairing and/or copulatory. (Notes of this type are not usually 

 uttered immediately before copulation attempts (see below) but this 

 does not necessarily preclude the possibility that birds uttering such 

 notes have activated copulatory tendencies.) Very occasionally iso- 

 lated adult males will utter the same or very similar notes singly during 

 later periods of the day at the height of the breeding season. There is 

 no reason to suppose that these single notes are not produced by 

 the same type of motivation as the series during Dawn Calling. These 

 single notes are very reminiscent of the "Plaintive Notes" of some 

 other species of tanagers and finches. It is possible, therefore, that 

 the "Kioo" or "Klioo" patterns of yellow-rumped tanagers are also 

 largely or completely homologous with the Plaintive Notes of such 

 species as the brown-capped bush-tanager and the green-backed 

 sparrow, Arremonops ccmirostris.* All or most of them probably 

 function to attract females. 



Yellow-rumped tanagers seem to utter Nasal Notes about as fre- 

 quently as crimson-backed tanagers do in similar circumstances. They 



8 All references to the green-backed sparrow throughout this paper are based 

 upon Moynihan, 1963. 



