Female Common Merganser and 7 young by Mike Carey

All About Birds says that Common Merganser are large, long-bodied ducks with thin, pointed wings. Their bills are straight and narrow, unlike the wide, flat bill of a “typical” duck, and the females have shaggy crests on the backs of their heads. Although these ducks look pretty punk & cool, the Tip of the Mitt Watershed Council reminds us that Merganser ducks are the main culprit in the spread of swimmers itch:

Swimmer’s itch (cercarial dermatitis) is a skin irritation caused by a larval form of certain flatworms from the family Schistosomatidae. Schistosome flatworms are parasites with complex life cycles usually involving certain species of snails and waterfowl. Upon hatching, free swimming Schistosomatidae larvae seek out an intermediary host, usually snails, to continue the life cycle. The larvae, known as cercariae, are only 1/32 of an inch long and generally invisible to the naked eye. Since humans are not the proper host, the larvae soon die upon mistakenly burrowing into the skin. The resulting skin condition and itching sensation is caused by an immune response to the dead larvae under the skin and symptoms vary by person. In many Michigan lakes, the common merganser duck is the primary or sole vertebrate host.

I am for sure NOT calling for the killing of mergansers, but as someone who has spent a lot of time on lakes with swimmers itch, I encourage you to practice safe swimming where you see these ducks:

1. Don’t swim first thing in the morning
2. Swim offshore and away from downwind areas
3. Rinse your body with clean water and towel off thoroughly after swimming!

Mike took these on Bear Lake a couple weeks ago. See more in his Bear Lake 2024 gallery on Flickr.

More duckies on Michigan in Pictures!

Young Common Mergansers resting on dock by Mike Carey