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Late November Birds at Duck Hole


Ring-billed gull and common merganser, Duck Hollow, 23 Nov 2022 (photo by Charity Kheshgi)

26 November 2022

This week Charity Kheshgi and I saw ring-billed gulls (Larus delawarensis), a common merganser (Mergus merganser) and a few pied-billed grebes (Podilymbus podiceps) at Duck Hollow. All three species visit the Monongahela River in November when freshwater freezes up north.

Pied-billed grebe in silhouette, Duck Hollow, 23 Nov 2022 (photo by Charity Kheshgi)

The common merganser gave us an opportunity to mentally compare her field marks to a similar bird. Here are some tips.

Female common and red-breasted mergansers are so similar that it takes some practice to tell them apart. Charity’s photos show the common merganser’s two unique field marks:

  • A sharp demarcation between dark head versus white breast / gray back.
  • A sharply defined white under-chin.

Notice the common merganser field marks in three photos.

Common mergansers at Duck Hollow, 16 Nov 2022 (photo by Charity Kheshgi)
Common merganser, not showing its crest, Duck Hollow, 16 Nov 2022 (photo by Charity Kheshgi)
Common mergansers — unique field marks in blue (photo by Charity Kheshgi)

Female red-breasted mergansers (Mergus serrator) lack those sharp lines. The colors blend from one to the other.

Red-breasted merganser (photo from Wikimedia Commons)

Note that the presence of a head crest is not a reliable difference between the two; both can display it.

So here’s a quiz: Which species is in the photo below? Are these common or red-breasted mergansers?

Which merganser is this? (photo from Wikimedia Commons)

p.s. Location, location, location! Of the two species, common mergansers are inland birds more likely in Pittsburgh in November. Red-breasted mergansers concentrate at the coasts and Great Lakes in winter.

(photos by Charity Kheshgi and red-breasted mergansers from Wikimedia Commons)



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