The iberian chiffchaff is a subspecies of the European chiffchaff and lives mainly in Portugal and Spain and has a more pronounced yellow colouration.
In Belgium, this bird is a VERY RARE stray guest.
Me very happy with the observation and photo :-))
Dutch name : Iberische tjiftjaf
German name : Iberienzilpzalp
Latin name : Phylloscopus ibericus