A total of 1404 advertising songs of five species of Passerina, P. leclancherii, P. ciris., P. versicolor, P. cyanea, and P. amoena, were analyzed by measurement of sonagrams. Songs of P. amoena, P. cyanea and P. versicolor characteristically have compound elements, i.e., elements composed of more than one syllable, whereas the songs of P. leclancherii and P. ciris typically include only simple elements, elements of only one syllable. Songs of P. amoena, P. cyanea and P. leclancherii have essentially no repetition of elements. Student's t-test of the means of the frequency of each species indicated that the frequency ranges of amoena and leclancherii were very significantly different from each other and from those of cyanea and ciris. The frequency ranges of cyanea and ciris, however, were not significantly different from each other. In general the arrangement of the five species according to similarities in song structure parallels the morphological grouping of the species.
