Flight call variation and vocal repertoire in the Hooded Grosbeak Hesperiphona abeillei

Introduction Many species in the cardueline finches (Fringillidae) display complex intraspecific diversity in social vocalizations, providing a rich system to study the evolution and maintenance of divergence in acoustic signals. Yet, formal descriptions of vocal variation are unavailable for a majority of Fringillids globally, especially in tropical taxa. Methods Here we describe geographic variation in vocalizations of Hooded Grosbeaks ( Hesperiphona abeillei ) and qualitatively compare the call structures with its congener, Evening Grosbeak ( Hesperiphona vespertinus ) using recordings from two community science databases that archive sound files along with geo-referenced location information. Recordings identified as social calls of Hooded Grosbeaks were classified into potential groupings through independent qualitative (location-blind expert opinion) and quantitative (cluster analysis and discriminant function analysis) methods. Results Results revealed a complex vocal repertoire containing more diversity in song and plasticity in call elements than that of the Evening Grosbeak. Both classification methods concurrently identified at least three distinct subgroups of flight calls, one of which was geographically differentiated (southern Mexico to Guatemala) from the other groups, which appeared to be more widespread across the Sierra Madre in Mexico. Discussion The combined structural and geographic differences among populations suggest the existence of a complex of learned call types similar to those of the Evening Grosbeak and Red Crossbill. Establishing further understanding of the geographic variation in Hooded Grosbeak calls will require additional geo-referenced recordings, as well as further field studies clarifying the behavioral significance flight calls, songs, and other vocalizations in the Hooded Grosbeak.