Response to typical, mixed and shortened song versions in Eurasian treecreepers, Certhia familiaris

Eurasian treecreepers, Certhia familiaris, exhibit an extremely low song variation, with particular males singing only a few variants of basically the same song type. However, males of this species are known to sing shortened and mixed song versions, which contain notes typical for the sibling short-toed treecreeper, C. brachydactyla. In this study we compared the response of Eurasian treecreeper males to playbacks of typical, shortened and mixed song versions in order to find potential differences in their signal value. We conducted playback experiments in W Poland in a sympatric population with no inter-specifc territoriality.We found that Eurasian treecreepers respond to all kinds of stimuli in a similar way, so all versions of song used in playback experiments are seem to carry a similar signal value. The Eurasian treecreeper song seems to be less stereotyped than that of the short-toed treecreeper, which is consistent with frequent occurrence of mixed singers of the first species in Central Europe.

Tomasz S. Osiejuk & Lechoslaw Kuczynski, Biologia, Bratislava, 58: 985-989, 2003