Unless someone out there knows differently, this is a Common Merganser duck, which I think is uncommonly handsome.
Males, females, juvenile males, and non-breeding males are russet-headed. During the breeding season, males have dark-green, sleek heads on dark bodies. This guy is probably a male, since it is winter and his body is black not gray.
Mergansers are somewhat smaller than Mallards, weighing in at about a pound lighter although they are about the same size in the water, just longer and leaner.
This is undoubtedly a lady. Note the light gray body.
Your guess is as good as mine as to the sex of these two. The bodies are darker; they may be males.
Who cares? They are rather pretty and -- I've never seen any before.
Every day offers new opportunities for living if we just open our eyes and our hearts. Have an uplifting day!