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Common Mergansers Migrating

11-14-14  common mergansers 120Common Mergansers are hardy, fish-eating, cavity-nesting ducks that can be found in New England year round, as they winter as far north as open water allows. However, the birds we see in the winter on large bodies of water most likely are not the same birds that breed here. All North American populations of Common Mergansers migrate, generally short to intermediate distances. Populations near the coast move only short distances, while more interior birds migrate farther. Heavier birds and adult males seem to tolerate colder winter temperatures and remain farther north than immature birds. They can often be seen on large lakes and rivers, as well as the coast, where they form small groups that may gather into large numbers at favored sites.

Migrating Common Mergansers tend to leave late in the fall (this week marks the peak of their fall migration), making them often the last waterfowl migrants to head south. Common Mergansers typically migrate over land at night, and along seacoasts or major river systems by day. In the spring, adult males return north first as soon as open water is available, followed by females a few weeks later. (Photo: 2 juvenile Common Mergansers) Thanks to canoe-steadying Sadie Richards for making it possible for me to take this photograph.

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7 responses

  1. Suzanne

    Beautiful photo! Something tells me there’s a bit of a story behind the “canoe-steadying” remark.

    I showed my husband (very picky ornithologist) the pic and he says great photo, but they are juveniles, unable to tell gender. The clue is the little separate white stripe under the eye, which adult males in nonbreeding plumage don’t have. He showed me pics in Sibley’s and (as usual with bird matters ONLY ha ha) he’s right.


    Sent from my iPad


    November 13, 2014 at 12:48 pm

    • Hi Suzanne,
      I must have checked Sibley’s 12 times, to make sure these were adults, as I had my doubts, but I decided they were adults due to the white coverts, which Sibley does not show on the juvenile! I totally accept your husband’s i.d. but do find it odd that Sibley didn’t show the white coverts on the male adult image.

      November 14, 2014 at 1:51 pm

  2. Hi Mary–I learn so much from your daily posts! Here’s a question about common mergansers that I hope you can answer. In the Maine Woods, I see both male and female common mergansers in the spring when many birds are returning from their wintering grounds; the males are easy to spot because of their black-and-white breeding plumage. Then later in the summer, I see what appear to be females (often with chicks in tow–I’m assuming the mergansers with chicks really are females) on many local bodies of water; however, I never see black-and-white males. Where do the males go? Or is it just that they have lost their breeding plumage so that they are indistinguishable–to my untrained eye–from the females?

    November 13, 2014 at 2:10 pm

    • (When I posted my comment just above, I forgot to check the box to be notified of new comments via email–so am posting this additional message now.)

      November 13, 2014 at 2:12 pm

      • Hi Wendy,
        It’s usually around July when the males’ plumage changes, but even so, you probably haven’t seen the males with young……the female selects the nest cavity, incubates, broods and spends the first few weeks with her young. Males remain nearby until the start or shortly after the start of incubation. While males have been seen with female and young, it’s not usual. I can’t tell you where the males go, but if you’ve seen young with an adult, it’s most likely an adult female. (The mergansers in the photo turn out to be young, not adult males, though their plumage is very similar!)

        November 14, 2014 at 2:09 pm

      • Thanks for your response, Mary! I’m now thinking that some common mergansers I’ve seen in late summer and judged to be chickless females were actually adult males (who had switched back to non-breeding plumage) or juveniles.

        November 14, 2014 at 3:09 pm

  3. I love seeing the merganzers on our river, they are the most common duck we see. I esp. love seeing the little fuzzball chicks in spring.

    November 14, 2014 at 2:44 am

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