Grabovsky V.I., Panov E.N.
Songs of pied and black-eared wheatears from localities where only one of the species is present as well as songs of "pure" and hybrid male phenotypes from three zones of secondary contact and hybridization were described and compared to test the hypothesis of character displacement. Overall 195 song variants performed by 84 males were analyzed. Songs of both species are made up of the same basic elements (notes, figures), but differ markedly by quantitative ratios of various types of such elements and by patterns of song temporal organization. In all secondary contact zones studied apparent reduction of initial interspecific differences in song characters was recorded, so that styles of singing predominating in these populations become intermediate between those typical for pied and black-eared wheatears, Males of both "pure" and hybrid phenotypes have in each mixed/hybrid population a similar style of singing. It was shown that in the case of quantitative predominance of certain parental phenotype (e.g. pleschanka) in the given population, the style of singing typical for this population can be more similar to style of singing of the another species (e.g. O. hispanica).
ГРАБОВСКИЙ В.И., ПАНОВ Е.Н., РУБЦОВ А.С.