migratory bird ID

November 7, 2007 11:48 AM

Please help me identify the birds I've been seeing paddling around Boston Harbor/Dorchester Bay these past few weeks. Snow white feathers on the back, dark otherwise. Don't know if it's some sort of duck or goose.

I started jogging around Columbia Point this past summer and got to know the gulls, ducks, and cormorants who live in the water there but a few weeks ago these beautiful birds appeared which I've been unable to identify. Brilliant white feathers on the back, dark feathers on the rest of the body, the kind of bill that extends pretty far around the head, bigger than a mallard, smaller than a canada goose. I've seen up to a half-dozen at a time diving and fishing along the shore. What are these birds?

posted by otio to Science & Nature (6 answers total)

They dive?

Maybe loons? More info would help - is the bill long and pointy, or rounded and shapped more like a mallard's? Is the head mostly dark, or mostly light? What sort of pattern does it have on the head (if there is one) - e.g., "spectacles", or a big, different-colored crown stripe, etc. A picture would be even better...
posted by rtha at 11:55 AM on November 7, 2007

Best answer: Oh, hey - looks like the common eider might hang out there. Might it be them? They're divers, and fairly large.
posted by rtha at 11:58 AM on November 7, 2007

Response by poster: Thanks for your help rtha. They do indeed dive. The bill is rounded and orangish like a mallard's except it extends farther around the head as I mentioned. The main distinguishing characteristic is the snow white feathers on the back. The head and rest of the body are dark and I haven't gotten close enough to see if it's black or dark green or if there are different shades of dark, etc. It's definitely not a loon but it could be a common eider though I'm not sure. They don't look anything like some of the pictures there but this picture looks pretty close actually. You could be right. I'll look into it and see if they're color patterns vary because the white on the birds I've seen definitely doesn't extend around the breast.
posted by otio at 12:12 PM on November 7, 2007

Response by poster: Looking into it more I think they are eiders. I had looked at eiders before but the example photographs were so different from what I saw. This beautiful specimen, for instance, bears almost no resemblance but this guy and this guy are more like it.
posted by otio at 12:34 PM on November 7, 2007

Yup, that's an eider! (I'm so jealous - when I lived in Boston, I cared not so much for birds; now I'm in SF, and I'm mad about them, and we have no eiders here!) They're likely in their "eclipse" plumage - that is, they're molting or have molted out of their breeding plumage and into something drabber, and at this time of year, may be in the process of molting from the drabber plumage back into their breeding plumage. Most ducks spend the winter in their breeding plumage, depending on if they migrate before or after molt. Yay for you - it looks like they're pretty common around there in the winter, according to Audubon's Christmas bird count records, so you'll probably get to see them in all their gorgeousness.
posted by rtha at 12:47 PM on November 7, 2007

Response by poster: Yeah, they are beautiful birds and I think they may be moving back into breeding plumage, as you surmise, because the plumage on their backs is spectacularly white at the moment just not much yet on the rest of the body.

I've never been much into birds myself but I've really enjoyed watching the cormorants as they fish. I saw one wrestle with an eel for a good minute before choking it down. A little repulsive but very entertaining.

Thanks for the help!
posted by otio at 1:01 PM on November 7, 2007