Resting Common Mersanger

Here's a Common Merganser I met late last summer. This was a slightly unusual sighting for mid-September since most Common Mergansers breed north of us during the spring/summer and then visit our area over the winter. Still, we're really not too far from the southern part of their breeding range; they're supposed to breed in northern NJ and adjacent parts of NY and PA. And it's also possible this was just an early migrator.

It's a little hard to tell if this is a male or a female. When we see them over the winter, the males already have their breed plumage which consists of green feathers on the head. But in September they've usually got their non-breeding plumage where they look much more like the brown-headed females (and juveniles).

When the males have their green plumage, the green manifests itself in 2 ways that combine blue and yellow:

  1. The yellow coloring comes from pigmentation. If you pulverize the feathers, you'll see a powdery yellow.
  2. The blue coloring comes from the structure of the feathers. If you crushed the feathers up finely enough, you wouldn't see any blue. (Virtually no animals can produce blue pigment.)
September 16, 2022 at Duke Island Park
Photo 248764725, (c) jpviolette, some rights reserved (CC BY-NC)


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