All species of Mergansers are beautiful diving ducks. But… Common and Red-breasted Mergansers can be found in the same areas, and both males and females can be confusing to decipher. No need for panic – here are some ways to solve the riddle.
1 -PROFILE: Both species are large, slim, diving ducks. Red-breasted tend to sit lower in the water and sometimes swim with their head submerged.
2 – HEADS – Red-breasted Mergansers have longer necks and the males have a dark green, long, shaggy crest – both of which set them apart from Common Mergansers. But the shaggy head can be a red herring as females and immature Red-breasted Merganser males also have a shaggy crest (although light brown) and can be confused with female Common Mergansers who are greyish with rusty colored shaggy heads.
3 – HABITAT – Both species will use fresh water, but Red-breasted Mergansers are found in brackish and marine waters more frequently than Common Mergansers.
If you still are in doubt look for:
4 – COLOR PATTERNS: Breeding males will be the easiest way to make the ID.
Look for the long, dark green shaggy feathers on the head. If you see this, a white neck band and wing stripe, and patterned back and shoulders with a beautiful almost lacy black-and-white pattern, and the cinnamon breast for which this bird was named, this is a male Red-breasted Merganser.
If the first thing you notice is a whole lot of white – a fully white breast, sides and a sharply defined iridescent green head, this is a Common Merganser male.