Acoustic differences between populations of western and eastern Bonelli's Warblers (Phylloscopus bonelli, Sylviidae)

Sonographic analyses of songs and calls of Bonelli's Warbler (Phylloscopus bonelli) show important structural differences between the geographically isolated western (P.b. bonelli) and eastern (P.b. orientalis) populations. Playback experiments in the field and some morphological differences suggest that these populations may be separating into 2 species.