A CATALOG OF SONG SYLLABLES OF INDIGO AND LAZULI BUNTINGS

Tape recording of singing male Indigo Buntings (Passerina cyanea) and Lazuli Buntings (P. amoena) from allopatric populations produced catal ogs of 127 indigo and 122 lazuli syllable types. These totals result f rom adding newly-described syllable types (29 indigo, 42 lazuli) to pr evious descriptions (Thompson 1970, 1976). While some syllable types a re more variable than others, the overall variation is remarkably disc ontinuous and syllable types are usually easily recognized. The same s yllable types occur and at similar frequencies of abundance in differe nt populations and at different times. The patterns of commoness and r arity of syllable types fit a ''broken-stick'' distribution, a model d eveloped to explain relative abundance of species in communities. Some syllable types are specialized in their position within songs, some a re used virtually anywhere in the song, but many are intermediate in d egree of specialization of position. Together with results from other studies of bunting songs, our data suggest that the individual syllabl es in bunting songs can be considered memes, the cultural equivalent o f genes. These syllable memes constitute the units of recombination fr om which whole-song variation is generated. A minor amount of variatio n is introduced by mutation of syllables. The syllable types are geogr aphically widely distributed and may be considered species universal s ong elements, similar to findings in the songs in populations of Swamp Sparrows (Melospiza georgiana, Marler and Pickert 1984). The stabilit y of syllables over space and time raises the possibility of a canaliz ing factor that guides the learning process in young buntings even dur ing cross-species syllable acquisition.