La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Garden Warblers Sylvia borin with mysterious songs.
Auteurs :	Goetz Rheinwald, Auteur ; Erich Hauth, Auteur ; Michael Kuhn, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (130(3) 2009)
Article en page(s) :	135-140
Résumé :	The observation of an abnormal singing Garden Warbler in the nature reserve Wahner Heide (North Rhine-Westphalia, western Germany) in 1985 was the starting point to search for more such cases. In total, 36 such singers were detected with accumulations in the 1950s and after 2000. The distribution ranges mainly through western Germany, Denmark, southern Sweden und Southwestern Finland, with only few birds detected west or east of this area. The songs of 31 of these birds were recorded, and 24 recordings were supplied for our study. In some cases, recordings of the same bird in different years were available. The recordings can be heard on the web site www.ginster-verlag.de.Up to now, no explanation for the abnormal song is available. It is obvious from the high variability that the birds did not learn from a different species. A defect of the syrinx can be excluded, too. Agreement exists that the birds produce a spontaneous song (called Kaspar-Hauser-song in German scientific literature), being unable to reproduce Garden Warbler elements in their own song. We discuss whether deafness may have inhibited to learn from adults or limited the development of the song. More investigations are necessary.

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