ИСТИНА

The plastic song stage often occurs during song ontogenesis in songbirds and takes an intermediate position between stages of subsong and crystallized (or definitive) adult song. Although in most species of birds plastic song normally occurs only during song development in the hatching year, in some species plastic song occurs in older birds. But the latter is described in laboratory conditions while the situation with wild birds, especially migrants, remains uncertain. We studied the structure and geographical variation of the Blyth's Reed Warbler song across almost the whole of its range and found no geographical dialects in this species. The only song that could be considered as a vocal dialect is the song that was recorded in Central Asia, yet there is no proof that Blyth’s Reed Warblers nest in those regions. Instead this species passes Central Asia during migrations. We analyzed structure and quantitative parameters of northern and southern songs of Blyth's Reed Warblers and found out that Blyth’s Reed Warbler used different modes of singing on breeding grounds and migration stopovers. According to our results we believe vocalizations of Blyth’s Reed Warblers on migration to be plastic song.