Mergansers are considered “diving ducks” and one of the things the three species of mergansers found in North America all have in common are their serrated bills. They all eat fish and their serrated bills must make it easier for them to grab on and hold fish after catching them.
The close up image of the nonbreeding, male Red-breasted Merganser (Mergus serrator) above shows the serrated bill. A nick name for these diving ducks is “Saw-bill” and I can certainly understand why.
Two species of mergansers that can be confused when making ID are the Common and Red-breasted Mergansers. Both are larger than Hooded Mergansers with Common Mergansers being slightly larger than Red-breasted Mergansers.
The Common Merganser (Mergus merganser) in the image above has a rustier colored head and crest than the Red-breasted Mergansers do in nonbreeding plumage, they have a deeper bill which often appears to be redder than the bill of the red-breasted. Common Mergansers have dark eyes and in nonbreeding plumage both sexes show a crescent shaped white patch on the chin.
The crests on Red-breasted Mergansers (Mergus serrator) always appear more wispy than the crests on Common Mergansers. The bill has a more orange cast to it than the bills of the Common Mergansers and it is also thin and more slender. Both sexes of the Red-breasted Merganser have red colored eyes.
Breeding grounds for both the Common and Red-breasted species overlap in some areas though Red-breasted Mergansers nest on the ground and Common Mergansers are cavity nesters who infrequently nest on the ground. Red-breasted Mergansers have the most northerly range extending into the Artic Circle and they also winter further south than the other two merganser species found in North America. Common Mergansers being a very hardy species will stay further north as long as the water remains open for them to fish.
Watching either the Common or Red-breasted Mergansers fish is a real treat which is exciting to view and photograph. Soon I should be seeing the males and females in eclipse or breeding plumage coming through where I live in Utah. I can’t wait to photograph them!