Common Scoter
Melanitta nigra
The common scoter is characterised by its bulky shape and large bill. The male is all black with a bulbous bill which shows some yellow coloration around the nostrils. The female is a brown bird with pale cheeks, very similar to female black scoter. This species can be distinguished from other scoters, apart from black scoter, by the lack of white anywhere on the drake and the more extensive pale areas on the female. The black scoter and common scoter have diagnosably distinct vocalisations.
ID text from Wikipedia, CC BY-SA 4.0
Surf Scoter
Melanitta perspicillata
The surf scoter reaches sexual maturity after 3 years. The adult male is on average 1,050 g (2.31 lb) and 48 cm (19 in) in length while the adult female averages about 900 g (2.0 lb) and 44 cm (17 in) in length, making this the smallest species of scoter on average. The surf scoter has a wingspan of 29.9–30.3 in (76–77 cm). The male is completely velvety black except for white patches on the forehead and the nape. It has a swollen bill, appearing orange at a distance but patterned with white, red and yellow, and a black spot near the base. Voice: Surf scoters are generally silent and their few vocalizations are poorly known. During courtship display, males perform a gurgling call and an explosive puk-puk. Females defend their young with a crowlike call. When alarmed, surf scoters will often make a sound like a "guk", somewhere between a "cluck" and a "tok", while rapidly surveying their environment or taking to flight en masse.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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