Cygnus cygnus
Same size as Mute Swan. Adults pure white and juveniles greyish. The bill is black with a yellow wedge reaching well beneath the nostrils. Juveniles differs from Mute Swan in lacking black lores, and having a pink tinge to the grey bill.
Quite vocal. Trumpet-like clear honks of half a second length most frequent in flight and take-off/landing. Often voiced with a register break.
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
Sounds:Hannu Jännes,http://www.xeno-canto.org ,Creative Commons Attribution-NonCommercial-ShareAlike 4.0
