Phyloscopus spec. - Raadselzanger
This Phyloscopus's song started as a Willow Warbler's (P. trochilus) but changed to a song similar to a rather melodious Chiffchaff's P. collybita song. Occasionally it sang not unlike an Iberian Chiffchaff P. ibericus. Visually it looked like a Willow Warbler.