Abstract
Intraspecific variation of passerine song may influence mate choice and consequently provides a potential mechanism for premating reproductive
isolation in birds. Notable geographic variation of songs is particularly common in widespread bird species, such as the coal
tit Periparus ater (Aves, Passeriformes, Paridae) having a large trans-Palearctic distribution range including allopatric populations. In this
study, measurement and analysis of 16 song parameters from different Western Palearctic populations showed a relatively uniform song in
all continental European and the island populations of Corsica and Sardinia. Song variation among and within these populations seems so
variable that there is a broad geographical overlap of acoustic parameters between populations. However, songs from northwest African
and Cypriot populations had lowest minimum frequencies and were thus significantly different from continental European, Corsican and
Sardinian populations. To test for intraspecific species recognition and potential acoustic isolation of different Palearctic populations, we
carried out field playback experiments on Central European coal tit males with songs from populations of the Eurasian (Germany, Latvia,
Russian Far East, Japan) and the Mediterranean region (northwest Africa, Cyprus, Corsica, Sardinia). Eurasian song types elicited similar
strong territorial reactions in Central European coal tits as local control songs. In contrast, none of the Mediterranean songs evoked any
notable reaction. Thus, there is geographic variation in coal tit song across continents that coincides with reduced species recognition between Central European and Mediterranean populations.
