Song repertoire of geographically isolated Chiff chaff population that formed in Crimean mountains in 1990s is analyzed. Th ere are 42 song elements in the Crimean Chiff chaff repertoire. A quarter of their song elements appear to be specific for this population because it is absent in neighboring European Chiff chaff populations from regions to the north (Ph. c. abietinus subspecies) and west (Ph. c. collybita subspecies). Comparison of song elements of Crimean Chiff chaffs with those of Caucasian birds of Ph. c. caucasica subspecies shows that they belong to same vocal population: specific elements in Crimean Chiff chaff songs are found also in songs of Caucasian birds. This is evidence that breeding population of Chiff chaff in Crimea originated from the species expansion from Caucasus, and that Crimean Chiff chaffs belong to Ph. c. caucasica subspecies.