The Greater Scaup is an abundant migrant and winter visitor in Oregon, particularly on coastal bays, lower river segments, and the Columbia River estuary.

Here are the descriptions of the male (drake) and female (hen) Greater Scaup:

Male (Drake) Greater Scaup
The male Greater Scaup is distinctly patterned, especially in its breeding (alternate) plumage, which is seen during the winter in Oregon.
Head, Neck, and Breast: Glossy black. The head is typically round and may show an iridescent sheen of dark green or purple depending on the light.
Body: The back and sides are pale gray or whitish with fine black lines (vermiculations). The belly and flanks are a striking white.
Rear: The rear end is black.
Bill and Eye: The bill is a light gray-blue with a black tip (nail). The eye is yellow or golden.
Non-breeding (Eclipse) Plumage: In summer, the male becomes duller, resembling the female but with a blackish head and mottled brown-and-gray body.

In summary, the drake is often described as being "black on both ends and white in the middle."

Female (Hen) Greater Scaup
The female is much less contrasting than the male, with shades of brown dominating her plumage.
Overall Color: Mostly dark brown.
Head: Darker brown than the body, with a prominent feature: a conspicuous white patch around the base of the bill, often called a "white mask."
Bill and Eye: The bill is a blue-gray with a black tip, similar to the male's. The eye is yellow.
Variation: The size of the white facial patch can vary.

In-Flight Identification (Both Sexes)
A key feature for both sexes, and a crucial way to distinguish them from the very similar Lesser Scaup, is their wing pattern:
Both have a bold white stripe on the secondary feathers that extends out into the primary feathers (towards the wingtip).

In Oregon, Greater Scaup are present from around September to mid-May as migrants and winter visitors, with most departing for northern breeding areas in the spring.