NO. 5 THE YELLOW-RUMPED TANAGER — MOYNIHAN 33 



Yellow-rumped tanagers are highly gregarious. They even asso- 

 ciate in semicolonial groups during the breeding season. 



They are highly vocal. They utter Nasal Notes, Rattles, and 

 melodious "Kioo" or "Klioo" Notes, plus a great number of inter- 

 mediate notes and calls, all or most of which intergrade with one 

 another. 



The comparatively great frequency of intermediate and inter- 

 grading vocal patterns may be a result of the extreme gregariousness 

 of the species. Any individual hearing a call or note will usually 

 receive visual information from its companion(s) at the same time. 

 This will facilitate the interpretation of any vocal message, even when 

 the latter is ambiguous or would be difficult to decipher by itself alone. 



Yellow-rumped tanagers seem to have more different types of dis- 

 play and partly independent components of display than all or most 

 related species. This may be correlated with their semicolonial breed- 

 ing habits. 



Many of the vocal patterns of yellow-rumped tanagers are very 

 similar to patterns of brown-capped bush-tanagers {Chlorospingus 

 opthalmicus) . The similarities are extensive and detailed enough to 

 suggest that the genera Ramphocelus and Chlorospingus are closely 

 related to one another. 



There is no display or combination of displays diagnostic of the 

 genus Ramphocelus as a whole. The display repertories of some 

 species of other genera are not more different from those of some 

 species of Ramphocelus than the latter are from one another. There 

 is some evidence that many of the differences between the repertory 

 of the yellow-rumped tanager and that of the sympatric crimson- 

 backed tanager (R. dimidiatus) subserve other functions instead of, 

 or in addition to, the maintenance of reproductive isolation between 

 the two species. 



BIBLIOGRAPHY 



Andrew, R. J. 



1961. The displays given by passerines in courtship and reproductive fight- 

 ing. Ibis, vol. 103a, pp. 315-348. 



ElSENMANN, E. 



1955. The species of Middle American birds. Trans. Linn. Soc. New York, 

 vol. 7, pp. 1-128. 

 Hellmaye, C. E. 



1936. Catalogue of birds of the Americas. Part IX, Tersinidae-Thraupidae. 

 Field Mus. Nat. Hist. Publ. 365, Zool. Ser., vol. 13, pp. 1-458. 



HlNDE, R. A. 



1955. A comparative study of the courtship of certain finches (Fringillidae). 

 Ibis, vol. 97, pp. 706-745. 



