Response of Male Indigo and Lazuli Buntings and Their Hybrids To Song Playback in Allopatric and Sympatric Populations

Abstract

AbstractThe hybridizing semispecies indigo and lazuli buntings (Passerina cyanea, P. amoena) were studied in song playback experiments in allopatric and sympatric populations. In allopatry, males of both species responded strongly to conspecific and weakly to heterospecific songs. In sympatry, indigo, lazuli and hybrid males reacted equally and strongly to both indigo and lazuli songs. Alteration of song structures, by presenting indigo syllables in lazuli temporal pattern and lazuli syllables in indigo temporal pattern, showed that the response of allopatric indigo and lazuli males was determined primarily by syllabic (phonological) cues in the test songs and not by the temporal pattern. The overall pattern of male response in sympatry and allopatry provides some understanding of the observed degree of reproductive isolation between these species.