Identification of Sea Ducks
American Sea Ducks generally have a robust body shape and short neck. Most species nest in the far north (Canada and northern Canada and Alaska). We have placed the eiders on their own page but they might also be considered sea ducks.
 Species of Sea Ducks:
Black Scoter – Due to its remote northern breeding season areas, much of what is known about Black Scoters range and reproduction has been learned relatively recently. Pairs are generally solitary, though while molting and during winter larger flocks may form. Rushing chases by Black Scoter males may occur during courtship.
Surf Scoter – breed on inland lakes but winter on the coasts, and migratory movements take place at night. When diving underwater, the behavior of Surf Scoters is variable. Sometimes they propel themselves with their feet alone, sometimes they extend their wings to help steer, and sometimes they propel themselves with both wings and feet.
White-winged Scoter – is known for the large, obvious patches of white in its wings is known as the Velvet Scoter in Europe, for the satiny-black plumage of the males. White-winged Scoters migrate mostly by day over land, but may travel either at night or by day over water.
Bufflehead – seen in winter over much of the U.S. actually nest in the boreal forests of Canada, using cavities in trees as their nest sites. Unlike many ducks which lay one egg each day, Buffleheads can take up to 3 days between eggs are laid.
Common Goldeneyes – are sometimes known as whistlers because their wings make a loud whistling sound when flapping. This sound seems to be more pronounced when temperatures are low. Common Goldeneyes are seldom found in flocks with other ducks.
Barrow‘s Goldeneye – Barrow’s and Common Goldeneyes will hybridize.  Hybrid females can be difficult to identify as a hybrid.  The white markings in front of the eye on the male is intermediate in shape between the crescent of the Barrow’s and the round shape on the Common Goldeneye.
Harlequin Duck – has an unusual pattern of habitat use and migration. It breeds along cold, fast-flowing mountain streams, but flies to the coast to spend the winter. Harlequin Ducks are excellent swimmers, able to cope with both fast currents and powerful surf, each of which they encounter at different times of the year.
Long-tailed Ducks –  are far more adept at swimming and diving than they are at flying or walking. When underwater, they use their wings rather than their feet for propulsion. Males begin courtship as early as the fall, although females are seldom receptive until February.
What you should know
1. Scoters, Harlequin Duck and Long-tailed Duck typically winter along coast lines.
2. Goldeneyes and Bufflehead will winter both inland and along coast lines.
3. Harlequin Duck, Long-tailed Duck, Surf Scoter and White-winged Scoter will use their wings to help provide propulsion when underwater. Most other diving ducks use just their feet.
4. Plumages can vary by age and sex.
5. Most adult males are distinctive.
6. Many printed field guides place Harlequin Duck and Long-tailed Duck in the same section as the eiders.  Eiders have a dedicated section in this guide.
7. Mergansers are fish eating ducks. Other sea ducks eat crustaceans and molluscs.
Identification challenges:
– Female scoters
– Female Barrow‘s and Common Goldeneye –  Males can be difficult but much less so than females.  The two species often interbreed.
Female goldeneyes
Adult Barrow‘s Goldeneye (first image) have yellow to orange bill.  However, first year females have a dark bill with a yellow tip, very similar to female Common Goldeneye.
Compare with the Common Goldeneye – 2nd photo.  Barrow‘s has a smaller, stubby looking bill and a high, more vertical forehead.  Can be difficult to discern at a distance.
Female Scoters
Black Scoter – Let’s start with the third bird in this set, the female Black Scoter.  It is the easiest of the female scoters to identify.  Pales cheek and neck contrast with the dark crown and back of the neck.  Amount of yellow on the bill variable and often not visible at a distance. First winter males have a similar appearance.
White-winged Scoter – The first image is a female White-winged Scoter.  Relatively easy ID in this photo as the white in the wing is visible.  When the white is not visible it can be difficult to distinguish from a female Surf Scoter.
First winter and adult females are similar, the first winter may be paler overall.  White marks on the face are variable in size and intensity.  The mark at the base of the bill tends to be ocal or circular in shape.  First winter males resemble females but have an orange tip on the bill.
Surf Scoter – The second image is a female Surf Scoter.  Again the pale facial markings are variable in size and intensity.  The mark at the base of the bill tends to take on a vertical shape.  Note the contrast between the dark crown and lighter cheek, similar to the Black Scoter.
While the birds are at least somewhat distinctive in these photographs it can be a different situation in the field.  Distance scoters bobbing up and down in the waves can be very difficult to identify.
