Fratercula arctica
Adults in summer at close range unmistakable. Bill in juveniles almost black, and much less deep than in adults. Adults in winter plumage also show much darker bill and cheeks than in summer. At a distance head gives an all dark impression, with characteristic dark "shadow " in front of the eye. Head and bill less elongated than in other auks. Wings rounded with dark undersides. "Thighs" dark. Flight fluttering and energic, with shifting weight and angle.
Deep, but not so coarse as Razorbill. Smoother and more gliding changes in pitch, like a "slow-motion" laugh or distant chainsaw; "aaaahrrr, aahr, ahr arh".
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
